Nomenclature Committee of the International Union of Biochemistry and Molecular Biology (NC-IUBMB)

Proposed Changes to the Enzyme List

The entries below are proposed additions and amendments to the Enzyme Nomenclature list. The entries below are proposed additions and amendments to the Enzyme Nomenclature list. They were prepared for the NC-IUBMB by Kristian Axelsen, Ron Caspi, Ture Damhus, Shinya Fushinobu, Julia Hauenstein, Antje Jäde, Masaaki Kotera, Andrew McDonald, Gerry Moss, Ida Schomburg and Keith Tipton. Comments and suggestions on these draft entries should be sent to Dr Andrew McDonald (Department of Biochemistry, Trinity College Dublin, Dublin 2, Ireland). The entries were added on the date indicated and fully approved after four weeks

An asterisk before "EC' indicates that this is an amendment to an existing enzyme rather than a new enzyme entry.


Contents

*EC 1.2.1.82 β-apo-4'-carotenal dehydrogenase (27 December 2023)
EC 1.3.1.126 2-epi-5-epi-valiolone dehydrogenase (27 December 2023)
EC 1.6.1.2 transferred now EC 7.1.1.1 (27 December 2023)
EC 1.8.1.22 dissimilatory sulfite reductase system (27 December 2023)
EC 1.8.5.10 [DsrC]-trisulfide reductase (27 December 2023)
EC 1.8.99.5 transferred now EC 1.8.1.22 (27 December 2023)
*EC 2.1.1.298 ribosomal protein uL3 N5-glutamine methyltransferase (27 December 2023)
EC 2.1.1.391 demethylgadusol O-methyltransferase (27 December 2023)
*EC 2.3.1.266 [ribosomal protein bS18]-alanine N-acetyltransferase (27 December 2023)
*EC 2.3.1.267 [ribosomal protein uS5]-alanine N-acetyltransferase (27 December 2023)
EC 2.3.3.22 3-carboxymethyl-3-hydroxy-acyl-[acp] synthase (27 December 2023)
EC 2.4.1.129 transferred now EC 2.4.99.28 (27 December 2023)
EC 2.4.1.394 4,6-α-glucanotransferase (linear substrates/linear products) (27 December 2023)
EC 2.4.1.395 reuteransucrase (27 December 2023)
EC 2.4.1.396 4,6-α-glucanotransferase (linear and branched substrates, branched products) (27 December 2023)
EC 2.4.99.28 peptidoglycan glycosyltransferase (27 December 2023)
*EC 2.8.4.4 [ribosomal protein uS12] (aspartate89-C3)-methylthiotransferase (27 December 2023)
EC 3.1.1.122 carbendazim hydrolysing esterase (27 December 2023)
*EC 3.1.3.62 multiple inositol-polyphosphate phosphatase (27 December 2023)
EC 3.1.8.2 transferred now EC 3.8.2.2 (27 December 2023)
EC 3.2.1.221 MMP endo-(1,4)-3-O-methyl-α-D-mannosidase (27 December 2023)
EC 3.2.1.222 funoran endo-β-hydrolase (27 December 2023)
EC 3.2.1.223 arabinogalactan exo α-(1,3)-β-L-arabinopyranosyl-(1→3)-L-arabinofuranosidase (non-reducing end) (27 December 2023)
EC 3.4.21.123 kumamolysin (27 December 2023)
*EC 3.4.24.84 Ste24 endopeptidase (27 December 2023)
EC 3.4 Acting on peptide bonds (peptidases) (27 December 2023)
EC 3.4.26 Glutamic endopeptidases (27 December 2023)
EC 3.4.26.1 intramembrane prenyl-peptidase Rce1 (27 December 2023)
EC 3.4.26.2 scytalidoglutamic peptidase (27 December 2023)
*EC 3.5.1.12 biotinidase (27 December 2023)
EC 3.8.2.2 diisopropyl-fluorophosphatase (27 December 2023)
*EC 4.1.1.87 malonyl-[malonate decarboxylase] decarboxylase (27 December 2023)
EC 4.1.1.124 malonyl-[acp] decarboxylase (27 December 2023)
EC 4.1.1.125 4-carboxy-3-alkylbut-2-enoyl-[acp] decarboxylase (27 December 2023)
EC 4.1.1.126 anhydromevalonate phosphate decarboxylase (27 December 2023)
EC 4.2.1.181 3-carboxymethyl-3-hydroxy-acyl-[acp] dehydratase (27 December 2023)
EC 4.2.1.182 phosphomevalonate dehydratase (27 December 2023)
EC 4.2.2.29 peptidoglycan lytic transglycosylase (27 December 2023)
EC 4.2.3.212 (+)-δ-cadinol synthase (27 December 2023)
EC 4.2.3.213 colleterpenol synthase (27 December 2023)
EC 4.2.3.214 dolasta-1(15),8-diene synthase (27 December 2023)
EC 4.2.3.215 δ-araneosene synthase (27 December 2023)
EC 4.2.3.216 somaliensene A synthase (27 December 2023)
EC 4.2.3.217 somaliensene B synthase (27 December 2023)
EC 4.2.3.218 variediene synthase (27 December 2023)
EC 4.2.3.219 (2E)-α-cericerene synthase (27 December 2023)
EC 6.7.1.2 3-aminoavenalumate diazotase (27 December 2023)
*EC 7.1.1.3 ubiquinol oxidase (H+-transporting) (27 December 2023)

*EC 1.2.1.82

Accepted name: β-apo-4'-carotenal dehydrogenase

Reaction: 4'-apo-β,ψ-caroten-4'-al + NAD+ + H2O = neurosporaxanthin + NADH + 2 H+

For diagram of reaction, click here

Glossary: neurosporaxanthin = 4'-apo-β,ψ-caroten-4'-oic acid

Other name(s): β-apo-4'-carotenal oxygenase; YLO-1; carD (gene name)

Systematic name: 4'-apo-β,ψ-carotenal:NAD+ oxidoreductase

Comments: Neurosporaxanthin is responsible for the orange color of of Neurospora.

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:

References:

1. Estrada, A.F., Youssar, L., Scherzinger, D., Al-Babili, S. and Avalos, J. The ylo-1 gene encodes an aldehyde dehydrogenase responsible for the last reaction in the Neurospora carotenoid pathway. Mol. Microbiol. 69 (2008) 1207-1220. [PMID: 18627463]

2. Diaz-Sanchez, V., Estrada, A.F., Trautmann, D., Al-Babili, S. and Avalos, J. The gene carD encodes the aldehyde dehydrogenase responsible for neurosporaxanthin biosynthesis in Fusarium fujikuroi. FEBS J. 278 (2011) 3164-3176. [PMID: 21749649]

[EC 1.2.1.82 created 2011, modified 2023]

EC 1.3.1.126

Accepted name: 2-epi-5-epi-valiolone dehydrogenase

Reaction: 2-epi-5-epi-valiolone + NAD+ = demethylgadusol + NADH + H+

Glossary: 2-epi-5-epi-valiolone = (2S,3S,4S,5R)-2,3,4,5-tetrahydroxy-5-(hydroxymethyl)cyclohexan-1-one
demethylgadusol = (4R,5R)-2,3,4,5-tetrahydroxy-5-(hydroxymethyl)cyclohex-2-en-1-one

Other name(s): gadusol synthase

Systematic name: 2-epi-5-epi-valiolone:NAD+ 2,3-oxidoreductase

Comments: The enzyme, present in egg-laying vertebrates, is involved in biosynthesis of the UV absorbing compound gadusol. It is a bifunctional enzyme that also catalyses EC 2.1.1.391, demethylgadusol O-methyltransferase.

References:

1. Osborn, A.R., Almabruk, K.H., Holzwarth, G., Asamizu, S., LaDu, J., Kean, K.M., Karplus, P.A., Tanguay, R.L., Bakalinsky, A.T. and Mahmud, T. De novo synthesis of a sunscreen compound in vertebrates. Elife 4 (2015) . [PMID: 25965179]

[EC 1.3.1.126 created 2023]

[EC 1.6.1.2 Transferred entry: NAD(P)+ transhydrogenase (Re/Si-specific). Now classified as EC 7.1.1.1, proton-translocating NAD(P)+ transhydrogenase (EC 1.6.1.2 created 1986, modified 2013, deleted 2023)]

EC 1.8.1.22

Accepted name: dissimilatory sulfite reductase system

Reaction: a [DsrC protein]-trisulfide + NAD+ + 3 H2O = a [DsrC protein]-dithiol + sulfite + NADH + H+

Other name(s): siroheme sulfite reductase; DsrABL; hydrogen-sulfide:(acceptor) oxidoreductase (incorrect)

Systematic name: [DsrC protein]-trisulfide,NAD+ oxidoreductase (sulfite-forming)

Comments: Contains siroheme. The enzyme is essential in prokaryotic sulfur-based energy metabolism, including sulfate/sulfite reducing organisms, sulfur-oxidizing bacteria, and organosulfonate reducers. The system comprises the DsrAB reductase and the DsrL protein, which form a tight complex. The reaction involves the small protein DsrC, which is present in all the organisms that contain dissimilatory sulfite reductase. In sulfite reducers the DsrL component transfers two electrons from NADH to the DsrAB component, which then reduces the sulfur in sulfite to an S(II) intermediate that forms (together with two cysteine residues of DsrC) a trisulfide. In sulfur oxidizers the enzyme catalyses the opposite reaction [1].

References:

1. Schedel, M., Vanselow, M. and Trueper, H. G. Siroheme sulfite reductase from Chromatium vinosum. Purification and investigation of some of its molecular and catalytic properties. Arch. Microbiol. 121 (1979) 29-36.

2. Seki, Y., Sogawa, N. and Ishimoto, M. Siroheme as an active catalyst in sulfite reduction. J. Biochem. 90 (1981) 1487-1492. [PMID: 7338517]

3. Pott, A.S. and Dahl, C. Sirohaem sulfite reductase and other proteins encoded by genes at the dsr locus of Chromatium vinosum are involved in the oxidation of intracellular sulfur. Microbiology (Reading) 144 (1998) 1881-1894. [PMID: 9695921]

4. Oliveira, T.F., Vonrhein, C., Matias, P.M., Venceslau, S.S., Pereira, I.A. and Archer, M. The crystal structure of Desulfovibrio vulgaris dissimilatory sulfite reductase bound to DsrC provides novel insights into the mechanism of sulfate respiration. J. Biol. Chem. 283 (2008) 34141-34149. [PMID: 18829451]

5. Venceslau, S.S., Stockdreher, Y., Dahl, C. and Pereira, I.A. The "bacterial heterodisulfide" DsrC is a key protein in dissimilatory sulfur metabolism. Biochim. Biophys. Acta 1837 (2014) 1148-1164. [PMID: 24662917]

6. Loffler, M., Feldhues, J., Venceslau, S.S., Kammler, L., Grein, F., Pereira, I.AC. and Dahl, C. DsrL mediates electron transfer between NADH and rDsrAB in Allochromatium vinosum. Environ. Microbiol. 22 (2020) 783-795. [PMID: 31854015]

[EC 1.8.1.22 created 2015 as EC 1.8.99.5, transferred 2023 to EC 1.8.1.22 ]

EC 1.8.5.10

Accepted name: [DsrC]-trisulfide reductase

Reaction: hydrogen sulfide + a [DsrC protein]-dithiol + 2 quinone = a [DsrC protein]-trisulfide + 2 quinol

Other name(s): DsrMKJOP complex

Systematic name: hydrogen sulfide:[DsrC protein]-dithiol oxidoreductase (trisulfide-forming)

Comments: This enzyme complex is present in both sulfate-reducing bacteria and sulfur-oxidizing bacteria, and acts in opposite directions during the reductive and oxidative pathways, respectively. DsrM and DsrP contain b-type hemes, DsrJ contains c-type hemes, DsrO is a ferredoxin-like protein, and DsrK is the catalytic subunit that acts as a disulfide reductase on DsrC proteins that contain a trisulfide bridge [1,3,4]. The complex receives the electrons from the membrane quinone pool [2,3].

References:

1. Pott, A.S. and Dahl, C. Sirohaem sulfite reductase and other proteins encoded by genes at the dsr locus of Chromatium vinosum are involved in the oxidation of intracellular sulfur. Microbiology (Reading) 144 (1998) 1881-1894. [PMID: 9695921]

2. Pires, R.H., Venceslau, S.S., Morais, F., Teixeira, M., Xavier, A.V. and Pereira, I.A. Characterization of the Desulfovibrio desulfuricans ATCC 27774 DsrMKJOP complex - a membrane-bound redox complex involved in the sulfate respiratory pathway. Biochemistry 45 (2006) 249-262. [PMID: 16388601]

3. Grein, F., Pereira, I.A. and Dahl, C. Biochemical characterization of individual components of the Allochromatium vinosum DsrMKJOP transmembrane complex aids understanding of complex function in vivo. J. Bacteriol. 192 (2010) 6369-6377. [PMID: 20952577]

4. Santos, A.A., Venceslau, S.S., Grein, F., Leavitt, W.D., Dahl, C., Johnston, D.T. and Pereira, I.A. A protein trisulfide couples dissimilatory sulfate reduction to energy conservation. Science 350 (2015) 1541-1545. [PMID: 26680199]

[EC 1.8.5.10 created 2023]

[EC 1.8.99.5 Transferred entry: dissimilatory sulfite reductase. Now classified as EC 1.8.1.22, dissimilatory sulfite reductase system. (EC 1.8.99.5 created 2015, deleted 2023)]

*EC 2.1.1.298

Accepted name: ribosomal protein uL3 N5-glutamine methyltransferase

Reaction: S-adenosyl-L-methionine + [ribosomal protein uL3]-L-glutamine = S-adenosyl-L-homocysteine + [ribosomal protein uL3]-N5-methyl-L-glutamine

Other name(s): YfcB; PrmB

Systematic name: S-adenosyl-L-methionine:[ribosomal protein uL3]-L-glutamine (N5-glutamine)-methyltransferase

Comments: Modifies the glutamine residue in the glycylglycylglutamine (GGQ) motif of ribosomal protein uL3 (Gln150 in the protein from the bacterium Escherichia coli). The enzyme does not act on peptide chain release factor 1 or 2.

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:

References:

1. Heurgue-Hamard, V., Champ, S., Engstrom, A., Ehrenberg, M. and Buckingham, R.H. The hemK gene in Escherichia coli encodes the N5-glutamine methyltransferase that modifies peptide release factors. EMBO J. 21 (2002) 769-778. [PMID: 11847124]

[EC 2.1.1.298 created 2014, modified 2023]

EC 2.1.1.391

Accepted name: demethylgadusol O-methyltransferase

Reaction: S-adenosyl-L-methionine + demethylgadusol = S-adenosyl-L-homocysteine + gadusol

Glossary: demethylgadusol = (4R,5R)-2,3,4,5-tetrahydroxy-5-(hydroxymethyl)cyclohex-2-en-1-one
gadusol = (4R,5R)-3,4,5-trihydroxy-5-(hydroxymethyl)-2-methoxycyclohex-2-en-1-one

Other name(s): gadusol synthase; desmethyl gadusol O-methyltransferase

Systematic name: S-adenosyl-L-methionine:demethylgadusol 2-O-methyltransferase

Comments: The enzyme, present in egg-laying vertebrates, is involved in biosynthesis of the UV absorbing compound gadusol. It is a bifunctional enzyme that also catalyses EC 1.3.1.126, 2-epi-5-epi-valiolone dehydrogenase.

References:

1. Osborn, A.R., Almabruk, K.H., Holzwarth, G., Asamizu, S., LaDu, J., Kean, K.M., Karplus, P.A., Tanguay, R.L., Bakalinsky, A.T. and Mahmud, T. De novo synthesis of a sunscreen compound in vertebrates. Elife 4 (2015) . [PMID: 25965179]

[EC 2.1.1.391 created 2023]

*EC 2.3.1.266

Accepted name: [ribosomal protein bS18]-alanine N-acetyltransferase

Reaction: acetyl-CoA + an N-terminal L-alanyl-[bS18 protein of 30S ribosome] = CoA + an N-terminal N-acetyl-L-alanyl-[bS18 protein of 30S ribosome]

Other name(s): rimI (gene name)

Systematic name: acetyl-CoA:N-terminal L-alanyl-[bS18 protein of 30S ribosome] N-acetyltransferase

Comments: The enzyme, characterized from bacteria, is specific for protein bS18, a component of the 30S ribosomal subunit. cf. EC 2.3.1.267, [ribosomal protein uS5]-alanine N-acetyltransferase.

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number:

References:

1. Isono, K. and Isono, S. Ribosomal protein modification in Escherichia coli. II. Studies of a mutant lacking the N-terminal acetylation of protein S18. Mol. Gen. Genet. 177 (1980) 645-651. [PMID: 6991870]

2. Yoshikawa, A., Isono, S., Sheback, A. and Isono, K. Cloning and nucleotide sequencing of the genes rimI and rimJ which encode enzymes acetylating ribosomal proteins S18 and S5 of Escherichia coli K12. Mol. Gen. Genet. 209 (1987) 481-488. [PMID: 2828880]

[EC 2.3.1.266 created 1990 as EC 2.3.1.128, part transferred 2018 to EC 2.3.1.266, modified 2023]

*EC 2.3.1.267

Accepted name: [ribosomal protein uS5]-alanine N-acetyltransferase

Reaction: acetyl-CoA + an N-terminal L-alanyl-[uS5 protein of 30S ribosome] = CoA + an N-terminal N-acetyl-L-alanyl-[uS5 protein of 30S ribosome]

Other name(s): rimJ (gene name)

Systematic name: acetyl-CoA:N-terminal L-alanyl-[uS5 protein of 30S ribosome] N-acetyltransferase

Comments: The enzyme, characterized from bacteria, is specific for protein uS5, a component of the 30S ribosomal subunit. It also plays a role in maturation of the 30S ribosomal subunit. cf. EC 2.3.1.266, [ribosomal protein bS18]-alanine N-acetyltransferase.

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:

References:

1. Yoshikawa, A., Isono, S., Sheback, A. and Isono, K. Cloning and nucleotide sequencing of the genes rimI and rimJ which encode enzymes acetylating ribosomal proteins S18 and S5 of Escherichia coli K12. Mol. Gen. Genet. 209 (1987) 481-488. [PMID: 2828880]

2. Roy-Chaudhuri, B., Kirthi, N., Kelley, T. and Culver, G.M. Suppression of a cold-sensitive mutation in ribosomal protein S5 reveals a role for RimJ in ribosome biogenesis. Mol. Microbiol. 68 (2008) 1547-1559. [PMID: 18466225]

3. Roy-Chaudhuri, B., Kirthi, N. and Culver, G.M. Appropriate maturation and folding of 16S rRNA during 30S subunit biogenesis are critical for translational fidelity. Proc. Natl. Acad. Sci. USA 107 (2010) 4567-4572. [PMID: 20176963]

[EC 2.3.1.267 created 1990 as EC 2.3.1.128, part transferred 2018 to EC 2.3.1.267, modified 2023]

EC 2.3.3.22

Accepted name: 3-carboxymethyl-3-hydroxy-acyl-[acp] synthase

Reaction: an acetyl-[acp] + a 3-oxoacyl-[acp] = a 3-carboxymethyl-3-hydroxy-acyl-[acp] + [acp]

Other name(s): HMG-CoA synthase-like enzyme; aprE (gene name); curD (gene name); corE (gene name); bryR (gene name); pedP (gene name); 3-carboxymethyl-3-hydroxy-acyl-[acyl-carrier protein] synthase

Systematic name: acetyl-[acp]:3-oxoacyl-[acp] C-acetyltransferase (thioester-hydrolysing, carboxymethyl-forming)

Comments: This family of enzymes participates in a process that introduces a methyl branch into nascent polyketide products. The process begins with EC 4.1.1.124, malonyl-[acp] decarboxylase, which converts the common extender unit malonyl-[acp] to acetyl-[acp]. The enzyme is a mutated form of a ketosynthase enzyme, in which a Cys residue in the active site is modified to a Ser residue, leaving the decarboxylase function intact, but nulifying the ability of the enzyme to form a carbon-carbon bond. Next, EC 2.3.3.22, 3-carboxymethyl-3-hydroxy-acyl-[acp] synthase, utilizes the acetyl group to introduce the branch at the β position of 3-oxoacyl intermediates attached to a polyketide synthase, forming a 3-hydroxy-3-carboxymethyl intermediate. This is followed by dehydration catalysed by EC 4.2.1.181, 3-carboxymethyl-3-hydroxy-acyl-[acp] dehydratase (often referred to as an ECH1 domain), leaving a 3-carboxymethyl group and forming a double bond between the α and β carbons. The process concludes with decarboxylation catalysed by EC 4.1.1.125, 4-carboxy-3-alkylbut-2-enoyl-[acp] decarboxylase (often referred to as an ECH2 domain), leaving a methyl branch at the β carbon. The enzymes are usually encoded by a cluster of genes referred to as an "HMGS cassette", based on the similarity of the key enzyme to EC 2.3.3.10, hydroxymethylglutaryl-CoA synthase. While the enzyme is similar to EC 2.3.3.10, it is specific for an [acyl-carrier protein] (acp)-bound donor and does not interact with a CoA substrate as donor.

References:

1. Erol, O., Schaberle, T.F., Schmitz, A., Rachid, S., Gurgui, C., El Omari, M., Lohr, F., Kehraus, S., Piel, J., Muller, R. and Konig, G.M. Biosynthesis of the myxobacterial antibiotic corallopyronin A. Chembiochem 11 (2010) 1253-1265. [PMID: 20503218]

2. Buchholz, T.J., Rath, C.M., Lopanik, N.B., Gardner, N.P., Hakansson, K. and Sherman, D.H. Polyketide β-branching in bryostatin biosynthesis: identification of surrogate acetyl-ACP donors for BryR, an HMG-ACP synthase. Chem. Biol. 17 (2010) 1092-1100. [PMID: 21035732]

3. Grindberg, R.V., Ishoey, T., Brinza, D., Esquenazi, E., Coates, R.C., Liu, W.T., Gerwick, L., Dorrestein, P.C., Pevzner, P., Lasken, R. and Gerwick, W.H. Single cell genome amplification accelerates identification of the apratoxin biosynthetic pathway from a complex microbial assemblage. PLoS One 6 (2011) e18565. [PMID: 21533272]

4. Maloney, F.P., Gerwick, L., Gerwick, W.H., Sherman, D.H. and Smith, J.L. Anatomy of the β-branching enzyme of polyketide biosynthesis and its interaction with an acyl-ACP substrate. Proc. Natl. Acad. Sci. USA 113 (2016) 10316-10321. [PMID: 27573844]

5. Slocum, S.T., Lowell, A.N., Tripathi, A., Shende, V.V., Smith, J.L. and Sherman, D.H. Chemoenzymatic dissection of polyketide β-branching in the bryostatin pathway. Methods Enzymol. 604 (2018) 207-236. [PMID: 29779653]

[EC 2.3.3.22 created 2023]

[EC 2.4.1.129 Transferred entry: peptidoglycan glycosyltransferase. Now EC 2.4.99.28, peptidoglycan glycosyltransferase (EC 2.4.1.129 created 1984, modified 2002, deleted 2023)]

EC 2.4.1.394

Accepted name: 4,6-α-glucanotransferase (linear substrates/linear products)

Reaction: formation of a linear isomalto/malto-polysaccharide from linear malto-oligosaccharides

Other name(s): gtfB (gene name) (ambiguous); gtfC (gene name)

Systematic name: linear (1→4)-α-D-glucan:(1→4)/(1→6)-α-D-glucan 6-α-D-glucosyltransferase

Comments: The enzyme, originally discovered in lactic acid bacteria but later found in other organisms, is similar to EC 2.4.1.395, reuteransucrase, yet is not able to act on sucrose. The enzyme, which belongs to the glycoside hydrolase 70 (GH70) family, possesses both hydrolase and transglycosylase activities, cleaving α(1→4) linkages from the non-reducing end of linear maltooligosaccharides and synthesizing linear α(1→6)-glucan chains. It also possesses an endo-α(1→4)-glycosidase activity. Due to its narrow binding groove, it is not able to act on branched substrates. cf. EC 2.4.1.396, 4,6-α-glucanotransferase (linear and branched substrates, branched products).

References:

1. Kralj, S., van Geel-Schutten, G.H., Dondorff, M.MG., Kirsanovs, S., van der Maarel, M.JE.C. and Dijkhuizen, L. Glucan synthesis in the genus Lactobacillus: isolation and characterization of glucansucrase genes, enzymes and glucan products from six different strains. Microbiology (Reading) 150 (2004) 3681-3690. [PMID: 15528655]

2. Kralj, S., Grijpstra, P., van Leeuwen, S.S., Leemhuis, H., Dobruchowska, J.M., van der Kaaij, R.M., Malik, A., Oetari, A., Kamerling, J.P. and Dijkhuizen, L. 4,6-α-glucanotransferase, a novel enzyme that structurally and functionally provides an evolutionary link between glycoside hydrolase enzyme families 13 and 70. Appl. Environ. Microbiol. 77 (2011) 8154-8163. [PMID: 21948833]

3. Dobruchowska, J.M., Gerwig, G.J., Kralj, S., Grijpstra, P., Leemhuis, H., Dijkhuizen, L. and Kamerling, J.P. Structural characterization of linear isomalto-/malto-oligomer products synthesized by the novel GTFB 4,6-α-glucanotransferase enzyme from Lactobacillus reuteri 121. Glycobiology 22 (2012) 517-528. [PMID: 22138321]

4. Leemhuis, H., Dijkman, W.P., Dobruchowska, J.M., Pijning, T., Grijpstra, P., Kralj, S., Kamerling, J.P. and Dijkhuizen, L. 4,6-α-Glucanotransferase activity occurs more widespread in Lactobacillus strains and constitutes a separate GH70 subfamily. Appl. Microbiol. Biotechnol. 97 (2013) 181-193. [PMID: 22361861]

5. Gangoiti, J., Pijning, T. and Dijkhuizen, L. The Exiguobacterium sibiricum 255-15 GtfC enzyme represents a novel glycoside hydrolase 70 subfamily of 4,6-α-glucanotransferase enzymes. Appl. Environ. Microbiol. 82 (2016) 756-766. [PMID: 26590275]

6. Bai, Y., Gangoiti, J., Dijkstra, B.W., Dijkhuizen, L. and Pijning, T. Crystal structure of 4,6-α-glucanotransferase supports diet-driven evolution of GH70 enzymes from α-amylases in oral bacteria. Structure 25 (2017) 231-242. [PMID: 28065507]

7. Te Poele, E.M., van der Hoek, S.E., Chatziioannou, A.C., Gerwig, G.J., Duisterwinkel, W.J., Oudhuis, L.AA.CM., Gangoiti, J., Dijkhuizen, L. and Leemhuis, H. GtfC enzyme of Geobacillus sp. 12AMOR1 represents a novel thermostable type of GH70 4,6-α-glucanotransferase that synthesizes a linear alternating (α1→6)/(α1→4) α-glucan and delays bread staling. J. Agric. Food Chem. 69 (2021) 9859-9868. [PMID: 34427087]

[EC 2.4.1.394 created 2023]

EC 2.4.1.395

Accepted name: reuteransucrase

Reaction: formation of reuteran from sucrose

Glossary: reuteran = a high-molecular-mass branched α-glucan produced by the lactic acid bacterium Limosilactobacillus reuteri.

Systematic name: sucrose:α-D-glucan 4-α/6-α-D-glucosyltransferase

Comments: The glucansucrases transfer a D-glucosyl residue from sucrose to a glucan chain. They are classified based on the linkage of the transferred glucosyl residue. The enzyme, characterized from the lactic acid bacterium Limosilactobacillus reuteri strain 121, catalyses the hydrolysis of sucrose and the transfer of the D-glucose moiety to suitable acceptors (inclduing sucrose), forming the glucan reuteran, which is typical for these strains. The enzyme forms mostly α(1→4) glucosidic linkages, but also α(1→6) linkages. The presence of maltose significantly accelerate the initial rate of the reaction. See EC 2.4.1.5, dextransucrase.

References:

1. Kralj, S., van Geel-Schutten, G.H., Rahaoui, H., Leer, R.J., Faber, E.J., van der Maarel, M.J. and Dijkhuizen, L. Molecular characterization of a novel glucosyltransferase from Lactobacillus reuteri strain 121 synthesizing a unique, highly branched glucan with α-(1→4) and α-(1→6) glucosidic bonds. Appl. Environ. Microbiol. 68 (2002) 4283-4291. [PMID: 12200277]

2. Kralj, S., van Geel-Schutten, G.H., van der Maarel, M.JE.C. and Dijkhuizen, L. Biochemical and molecular characterization of Lactobacillus reuteri 121 reuteransucrase. Microbiology (Reading) 150 (2004) 2099-2112. [PMID: 15256553]

3. Kralj, S., Stripling, E., Sanders, P., van Geel-Schutten, G.H. and Dijkhuizen, L. Highly hydrolytic reuteransucrase from probiotic Lactobacillus reuteri strain ATCC 55730. Appl. Environ. Microbiol. 71 (2005) 3942-3950. [PMID: 16000808]

[EC 2.4.1.395 created 2023]

EC 2.4.1.396

Accepted name: 4,6-α-glucanotransferase (linear and branched substrates, branched products)

Reaction: formation of a branched isomalto/malto-polysaccharide from branched malto-oligosaccharides

Other name(s): gtfB (gene name) (ambiguous); gtfD (gene name)

Systematic name: branched (1→4)-α-D-glucan:(1→4)/(1→6)-α-D-glucan 6-α-D-glucosyltransferase

Comments: The enzyme, discovered in several bacterial species, is similar to EC 2.4.1.395, reuteransucrase, yet is not able to act on sucrose. The enzyme, which belongs to the glycoside hydrolase 70 (GH70) family, possesses both hydrolase and transglycosylase activities, cleaving endo α(1→4) linkages from the non-reducing end of maltooligosaccharides and adding the resulting oligosaccharides to the non-reducing end of α-D-glucan chains that terminate with a residue linked by an α-(1→4) linkage, forming an α(1→6) linkage. The enzyme is not able to form successive α(1→6) linkages. Unlike EC 2.4.1.394, 4,6-α-glucanotransferase (linear substrates/linear products), which can only act on linear substrates, this enzyme is able to act on both linear and branched substrates, and can form the branched reuteran type of α-glucan.

References:

1. Gangoiti, J., van Leeuwen, S.S., Vafiadi, C. and Dijkhuizen, L. The Gram-negative bacterium Azotobacter chroococcum NCIMB 8003 employs a new glycoside hydrolase family 70 4,6-α-glucanotransferase enzyme (GtfD) to synthesize a reuteran like polymer from maltodextrins and starch. Biochim. Biophys Acta 1860 (2016) 1224-1236. [PMID: 26868718]

2. Gangoiti, J., van Leeuwen, S.S., Meng, X., Duboux, S., Vafiadi, C., Pijning, T. and Dijkhuizen, L. Mining novel starch-converting glycoside hydrolase 70 enzymes from the Nestle Culture Collection genome database: the Lactobacillus reuteri NCC 2613 GtfB. Sci. Rep. 7 (2017) 9947. [PMID: 28855510]

3. Pijning, T., Gangoiti, J., Te Poele, E.M., Borner, T. and Dijkhuizen, L. Insights into broad-specificity starch modification from the crystal structure of Limosilactobacillus reuteri NCC 2613 4,6-α-glucanotransferase GtfB. J. Agric. Food Chem. 69 (2021) 13235-13245. [PMID: 34708648]

[EC 2.4.1.396 created 2023]

EC 2.4.99.28

Accepted name: peptidoglycan glycosyltransferase

Reaction: [GlcNAc-(1→4)-Mur2Ac(oyl-L-Ala-γ-D-Glu-L-Lys-D-Ala-D-Ala)]n-diphosphoundecaprenol + GlcNAc-(1→4)-Mur2Ac(oyl-L-Ala-γ-D-Glu-L-Lys-D-Ala-D-Ala)-diphosphoundecaprenol = [GlcNAc-(1→4)-Mur2Ac(oyl-L-Ala-γ-D-Glu-L-Lys-D-Ala-D-Ala)]n+1-diphosphoundecaprenol + undecaprenyl diphosphate

Glossary: Mur2Ac = N-acetylmuramic acid

Other name(s): PG-II; bactoprenyldiphospho-N-acetylmuramoyl-(N-acetyl-D-glucosaminyl)-pentapeptide:peptidoglycan N-acetylmuramoyl-N-acetyl-D-glucosaminyltransferase; penicillin binding protein (3 or 1B); peptidoglycan transglycosylase; undecaprenyldiphospho-(N-acetyl-D-glucosaminyl-(1→4)-N-acetyl-D-muramoylpentapeptide):undecaprenyldiphospho-(N-acetyl-D-glucosaminyl-(1→4)-N-acetyl-D-muramoylpentapeptide) disaccharidetransferase

Systematic name: [poly-N-acetyl-D-glucosaminyl-(1→4)-(N-acetyl-D-muramoylpentapeptide)]-diphosphoundecaprenol:[N-acetyl-D-glucosaminyl-(1→4)-N-acetyl-D-muramoylpentapeptide]-diphosphoundecaprenol disaccharidetransferase

Comments: The enzyme also works when the lysine residue is replaced by meso-2,6-diaminoheptanedioate (meso-2,6-diaminopimelate, A2pm) combined with adjacent residues through its L-centre, as it is in Gram-negative and some Gram-positive organisms. The undecaprenol involved is ditrans,octacis-undecaprenol (for definitions, click here). Involved in the synthesis of cell-wall peptidoglycan.

References:

1. Taku, A., Stuckey, M. and Fan, D.P. Purification of the peptidoglycan transglycosylase of Bacillus megaterium. J. Biol. Chem. 257 (1982) 5018-5022. [PMID: 6802846]

2. Goffin, C. and Ghuysen, J.-M. Multimodular penicillin-binding proteins: an enigmatic family of orthologs and paralogs. Microbiol. Mol. Biol. Rev. 62 (1998) 1079-1093. [PMID: 9841666]

3. van Heijenoort, J. Formation of the glycan chains in the synthesis of bacterial peptidoglycan. Glycobiology 11 (2001) 25. [PMID: 11320055]

[EC 2.4.99.28 created 1984 as EC 2.4.1.129, modified 2002, transferred 2023 to EC 2.4.99.28]

*EC 2.8.4.4

Accepted name: [ribosomal protein uS12] (aspartate89-C3)-methylthiotransferase

Reaction: L-aspartate89-[ribosomal protein uS12] + sulfur-(sulfur carrier) + 2 S-adenosyl-L-methionine + reduced acceptor = 3-(methylsulfanyl)-L-aspartate89-[ribosomal protein uS12] + S-adenosyl-L-homocysteine + (sulfur carrier) + L-methionine + 5'-deoxyadenosine + oxidized acceptor (overall reaction)
(1a) S-adenosyl-L-methionine + L-aspartate89-[ribosomal protein uS12] + sulfur-(sulfur carrier) = S-adenosyl-L-homocysteine + L-aspartate89-[ribosomal protein uS12]-methanethiol + (sulfur carrier)
(1b) L-aspartate89-[ribosomal protein uS12]-methanethiol + S-adenosyl-L-methionine + reduced acceptor = 3-(methylsulfanyl)-L-aspartate89-[ribosomal protein uS12] + L-methionine + 5'-deoxyadenosine + oxidized acceptor

Other name(s): RimO; [ribosomal protein S12]-Asp89:sulfur-(sulfur carrier),S-adenosyl-L-methionine C3-methylthiotransferase; [ribosomal protein S12]-L-aspartate89:sulfur-(sulfur carrier),S-adenosyl-L-methionine C3-methylthiotransferase

Systematic name: [ribosomal protein uS12]-L-aspartate89:sulfur-(sulfur carrier),S-adenosyl-L-methionine C3-(methylsulfanyl)transferase

Comments: This bacterial enzyme binds two [4Fe-4S] clusters [2,3]. A bridge of five sulfur atoms is formed between the free Fe atoms of the two [4Fe-4S] clusters [6]. In the first reaction the enzyme transfers a methyl group from AdoMet to the external sulfur ion of the sulfur bridge. In the second reaction the enzyme catalyses the reductive fragmentation of a second molecule of AdoMet, yielding a 5'-deoxyadenosine radical, which then attacks the methylated sulfur atom of the polysulfide bridge, resulting in the transfer of a methylsulfanyl group to aspartate89 [5,6]. The enzyme is a member of the superfamily of S-adenosyl-L-methionine-dependent radical (radical AdoMet) enzymes.

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number:

References:

1. Anton, B.P., Saleh, L., Benner, J.S., Raleigh, E.A., Kasif, S. and Roberts, R.J. RimO, a MiaB-like enzyme, methylthiolates the universally conserved Asp88 residue of ribosomal protein S12 in Escherichia coli. Proc. Natl. Acad. Sci. USA 105 (2008) 1826-1831. [PMID: 18252828]

2. Lee, K.H., Saleh, L., Anton, B.P., Madinger, C.L., Benner, J.S., Iwig, D.F., Roberts, R.J., Krebs, C. and Booker, S.J. Characterization of RimO, a new member of the methylthiotransferase subclass of the radical SAM superfamily. Biochemistry 48 (2009) 10162-10174. [PMID: 19736993]

3. Arragain, S., Garcia-Serres, R., Blondin, G., Douki, T., Clemancey, M., Latour, J.M., Forouhar, F., Neely, H., Montelione, G.T., Hunt, J.F., Mulliez, E., Fontecave, M. and Atta, M. Post-translational modification of ribosomal proteins: structural and functional characterization of RimO from Thermotoga maritima, a radical S-adenosylmethionine methylthiotransferase. J. Biol. Chem. 285 (2010) 5792-5801. [PMID: 20007320]

4. Strader, M.B., Costantino, N., Elkins, C.A., Chen, C.Y., Patel, I., Makusky, A.J., Choy, J.S., Court, D.L., Markey, S.P. and Kowalak, J.A. A proteomic and transcriptomic approach reveals new insight into β-methylthiolation of Escherichia coli ribosomal protein S12. Mol. Cell. Proteomics 10 (2011) M110.005199. [PMID: 21169565]

5. Landgraf, B.J., Arcinas, A.J., Lee, K.H. and Booker, S.J. Identification of an intermediate methyl carrier in the radical S-adenosylmethionine methylthiotransferases RimO and MiaB. J. Am. Chem. Soc. 135 (2013) 15404-15416. [PMID: 23991893]

6. Forouhar, F., Arragain, S., Atta, M., Gambarelli, S., Mouesca, J.M., Hussain, M., Xiao, R., Kieffer-Jaquinod, S., Seetharaman, J., Acton, T.B., Montelione, G.T., Mulliez, E., Hunt, J.F. and Fontecave, M. Two Fe-S clusters catalyze sulfur insertion by radical-SAM methylthiotransferases. Nat. Chem. Biol. 9 (2013) 333-338. [PMID: 23542644]

[EC 2.8.4.4 created 2014, modified 2014, modified 2023]

EC 3.1.1.122

Accepted name: carbendazim hydrolysing esterase

Reaction: carbendazim + H2O = 2-aminobenzimidazole + CO2 + methanol (overall reaction)
(1a) carbendazim + H2O = N-(1H-1,3-benzodiazol-2-yl)carbamate + methanol
(1b) N-(1H-1,3-benzodiazol-2-yl)carbamate = 2-aminobenzimidazole + CO2 (spontaneous)

Glossary: carbendazim = methyl 1H-benzimidazol-2-ylcarbamate; 2-aminobenzimidazole = 1H-benzimidazol-2-amine

Other name(s): mheI (gene name)

Systematic name: carbendazim methanol hydrolase (decarboxylating)

Comments: The enzyme, which is inducible in the soil bacterium Nocardioides sp. (strain SG-4G), catalyses the degradation of the fungicide carbendazim. Following hydrolysis of the carbamate ester, the carbamate decarboxylates spontaneously.

References:

1. Pandey, G., Dorrian, S.J., Russell, R.J., Brearley, C., Kotsonis, S. and Oakeshott, J.G. Cloning and biochemical characterization of a novel carbendazim (methyl-1H-benzimidazol-2-ylcarbamate)-hydrolyzing esterase from the newly isolated Nocardioides sp. strain SG-4G and its potential for use in enzymatic bioremediation. Appl. Environ. Microbiol. 76 (2010) 2940-2945. [PMID: 20228105]

[EC 3.1.1.122 created 2023]

*EC 3.1.3.62

Accepted name: multiple inositol-polyphosphate phosphatase

Reaction: (1) myo-inositol hexakisphosphate + H2O = 1D-myo-inositol 1,2,4,5,6-pentakisphosphate + phosphate
(2) 1D-myo-inositol 1,2,4,5,6-pentakisphosphate + H2O = 1D-myo-inositol 1,2,5,6-tetrakisphosphate + phosphate
(3) 1D-myo-inositol 1,2,5,6-tetrakisphosphate + H2O = 1D-myo-inositol 1,2,6-trisphosphate + phosphate
(4) 1D-myo-inositol 1,2,6-trisphosphate + H2O = 1D-myo-inositol 1,2-bisphosphate + phosphate
(5) 1D-myo-inositol 1,2-bisphosphate + H2O = 1D-myo-inositol 2-phosphate + phosphate

Glossary: myo-inositol hexakisphosphate = phytate
1D-myo-inositol 1,3,4,5,6-pentakisphosphate = Ins(1,3,4,5,6)P5
1D-myo-inositol 1,3,4,5-tetrakisphosphate = Ins(1,3,4,5)P4
1D-myo-inositol 1,4,5,6-tetrakisphosphate = Ins(1,4,5,6)P4
1D-myo-inositol 1,4,5-trisphosphate = Ins(1,4,5)P3
1D-myo-inositol 2,3-bisphosphate = Ins(2,3)P2
1D-myo-inositol 2-phosphate = Ins(2)P

Other name(s): MIPP; phytase (ambiguous); 1D-myo-inositol-hexakisphosphate 5-phosphohydrolase (incorrect)

Systematic name: myo-inositol-hexakisphosphate phosphohydrolase

Comments: This ubiquitous enzyme degrades myo-inositol hexakisphosphate (phytate) to Ins(2,3)P2 and Ins(2)P. Activities have been characterized in the yeast Saccharomyces cerevisiae [2], the plant Lupinus albus [3] and the bacteria Bacillus sp. [4] and Raoultella terrigena [5]. In mammal cells Ins(2,3)P2 and Ins(2)P are the major inositol phosphate compounds found [6]. The mammal enzyme is also active on Ins(1,3,4,5,6)P5 that is dephosphorylated to Ins(1,4,5,6)P4 and Ins(1,4,5)P3, and on 2,3-bisphospho-D-glycerate (cf. EC 3.1.3.80, 2,3-bisphosphoglycerate 3-phosphatase). In addition, it acts on Ins(1,3,4,5)P4 to yield Ins(1,4,5)P3 in vitro (cf. EC 3.1.3.67, phosphatidylinositol-3,4,5-trisphosphate 3-phosphatase) [7]. It does not hydrolyse phosphates from the 2-positions of inositol phosphates [6]. In other organisms the degradation of phytate follows different routes. (cf. EC 3.1.3.8, 3-phytase, EC 3.1.3.26, 4-phytase, and EC 3.1.3.72, 5-phytase).

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 116958-30-6

References:

1. Craxton, A., Caffrey, J.J., Burkhart, W., Safrany, S.T. and Shears, S.B. Molecular cloning and expression of a rat hepatic multiple inositol polyphosphate phosphatase. Biochem. J. 328 (1997) 75-81. [PMID: 9359836]

2. Greiner, R., Alminger, M.L. and Carlsson, N.G. Stereospecificity of myo-inositol hexakisphosphate dephosphorylation by a phytate-degrading enzyme of baker's yeast. J. Agric. Food Chem. 49 (2001) 2228-2233. [PMID: 11368581]

3. Greiner, R., Larsson Alminger, M., Carlsson, N.G., Muzquiz, M., Burbano, C., Cuadrado, C., Pedrosa, M.M. and Goyoaga, C. Pathway of dephosphorylation of myo-inositol hexakisphosphate by phytases of legume seeds. J. Agric. Food Chem. 50 (2002) 6865-6870. [PMID: 12405789]

4. Greiner, R., Farouk, A., Alminger, M.L. and Carlsson, N.G. The pathway of dephosphorylation of myo-inositol hexakisphosphate by phytate-degrading enzymes of different Bacillus spp. Can. J. Microbiol. 48 (2002) 986-994. [PMID: 12556126]

5. Greiner, R. and Carlsson, N.G. myo-Inositol phosphate isomers generated by the action of a phytate-degrading enzyme from Klebsiella terrigena on phytate. Can. J. Microbiol. 52 (2006) 759-768. [PMID: 16917535]

6. Nguyen Trung, M., Kieninger, S., Fandi, Z., Qiu, D., Liu, G., Mehendale, N.K., Saiardi, A., Jessen, H., Keller, B. and Fiedler, D. Stable isotopomers of myo-inositol uncover a complex MINPP1-dependent inositol phosphate network. ACS Cent. Sci. 8 (2022) 1683-1694. [PMID: 36589890]

7. Yu, J., Leibiger, B., Yang, S.N., Shears, S.B., Leibiger, I.B., Berggren, P.O. and Barker, C.J. Multiple inositol polyphosphate phosphatase compartmentalization separates inositol phosphate metabolism from inositol lipid signaling. Biomolecules 13 (2023) . [PMID: 37371464]

[EC 3.1.3.62 created 1992, modified 2002, modified 2023]

[EC 3.1.8.2 Transferred entry: diisopropyl-fluorophosphatase. Now classified as EC 3.8.2.2, diisopropyl-fluorophosphatase (EC 3.1.8.2 created 1961 as EC 3.8.2.1, transferred 1992 to EC 3.1.8.2, deleted 2023)]

EC 3.2.1.221

Accepted name: MMP endo-(1,4)-3-O-methyl-α-D-mannosidase

Reaction: Endohydrolysis of 3-O-methyl-α-D-mannosyl-(1→4)-3-O-methyl-D-mannose linkages within (1,4)-3-O-methyl-α-D-mannnan substrates

Glossary: MMP = 3-O-methylmannose polysaccharide = α-D-mannosyl-(1→4)-[3-O-methyl-α-D-mannosyl-(1→4)]n-1-O,3-O-dimethyl-α-D-mannose

Other name(s): MMP α-(1→4)-endomannosidase; mmpH (gene name)

Systematic name: (1,4)-3-O-methyl-α-D-mannan 4-α-3-O-methyl-D-mannohydrolase

Comments: The enzyme, present in mycobacterial species that produce 3-O-methylmannose polysaccharide (MMP), is involved in recycling and biosynthesis of the polymer. The enzyme has been shown to cleave substrates in the range of 11-14 mannose residues.

References:

1. Maranha, A., Costa, M., Ripoll-Rozada, J., Manso, J.A., Miranda, V., Mendes, V.M., Manadas, B., Macedo-Ribeiro, S., Ventura, M.R., Pereira, P.JB. and Empadinhas, N. Self-recycling and partially conservative replication of mycobacterial methylmannose polysaccharides. Commun Biol 6 (2023) 108. [PMID: 36707645]

[EC 3.2.1.221 created 2023]

EC 3.2.1.222

Accepted name: funoran endo-β-hydrolase

Reaction: Endohydrolysis of β-(1→4)-linkages between β-D-galactopyranose-6-sulfate and 3,6-anhydro-α-L-galactopyranose units in funoran

Glossary: funoran = [-3)-β-D-galactopyranose-6-sulfate-(1-4)-3,6-anhydro-α-L-galactopyranose-(1-]

Other name(s): β-funoranase

Systematic name: funoran endo β-(1,4)-glycanohydrolase

Comments: The enzyme is an endo hydrolase that hydrolyses the β(1,4) bond in funoran, a polysaccharide produced by red algae of the genus Gloiopeltis. The enzyme from the marine bacterium Wenyingzhuangia aestuarii OF219 acts on agarose with a higher efficiency (cf. EC 3.2.1.81, β-agarase), but binds funoran preferentially.

References:

1. Zhang, Y., Chen, G., Shen, J., Mei, X., Liu, G., Chang, Y., Dong, S., Feng, Y., Wang, Y. and Xue, C. The characteristic structure of funoran could be hydrolyzed by a GH86 family enzyme (Aga86A_Wa): Discovery of the funoran hydrolase. Carbohyd Polym 318 (2023) 121117.

[EC 3.2.1.222 created 2023]

EC 3.2.1.223

Accepted name: arabinogalactan exo α-(1,3)-β-L-arabinopyranosyl-(1→3)-L-arabinofuranosidase (non-reducing end)

Reaction: Hydrolysis of β-L-Arap-(1→3)-L-Araf disaccharides from non-reducing terminals in branches of type II arabinogalactan attached to proteins.

Glossary: Araf = arabinofuranose
Arap = arabinopyranose

Other name(s): 3-O-β-L-arabinopyranosyl-α-L-arabinofuranosidase; AAfase

Systematic name: type II arabinogalactan exo α-(1,3)-[β-L-arabinopyranosyl-(1→3)-L-arabinofuranose] hydrolase (non-reducing end)

Comments: The enzyme, characterized from the bacterium Bifidobacterium pseudocatenulatum, specifically hydrolyses β;-L-Arap-(1→3)-L-Araf disaccharides from the non-reducing terminal of arabinogalactan using an exo mode of action. It is active with arabinogalactan-proteins (AGPs) containing type II arabinogalactans such as gum arabic AGP and larch AGP. The enzyme can also hydrolyse α-D-Galp-(1→3)-L-Araf disaccharides (cf. EC 3.2.1.215) with a much lower activity.

References:

1. Sasaki, Y., Yanagita, M., Hashiguchi, M., Horigome, A., Xiao, J. Z., Odamaki, T., Kitahara, K. and Fujita, K. Assimilation of arabinogalactan side chains with novel 3-O-β-L-arabinopyranosyl-α-L-arabinofuranosidase in Bifidobacterium pseudocatenulatum. Microbiome Res. Rep. 2 (2023) 12.

[EC 3.2.1.223 created 2023]

EC 3.4.21.123

Accepted name: kumamolysin

Reaction: The enzyme preferentially hydrolyses peptides having an Ala or Pro residue at P2 position and prefers such charged amino acid residues as Glu or Arg at the P2' position. In the oxidized insulin B chain, kumamolysin preferentially cleaves between Leu15 and Tyr16

Other name(s): KSCP; kumamolisin

Comments: This bacterial pepstatin-insensitive carboxyl proteinase has been isolated and characterized from Bacillus sp. MN-32 and from several Burkholderia spp. Kumamolysin from Bacillus sp. MN-32 exhibits a Ser278/Glu78/Asp82 catalytic triad. The enzyme is a type example of peptidase family S53 in the MEROPS Peptidas Database.

References:

1. Murao, S., Ohkuni, K., Nagao, M., Hirayama, K., Fukuhara, K., Oda, K., Oyama, H. and Shin, T. Purification and characterization of kumamolysin, a novel thermostable pepstatin-insensitive carboxyl proteinase from Bacillus novosp. MN-32. J. Biol. Chem. 268 (1993) 349-355. [PMID: 8416942]

2. Oda, K., Ogasawara, S., Oyama, H. and Dunn, B.M. Subsite preferences of pepstatin-insensitive carboxyl proteinases from prokaryotes: kumamolysin, a thermostable pepstatin-insensitive carboxyl proteinase. J. Biochem. 128 (2000) 499-507. [PMID: 10965051]

3. Oyama, H., Hamada, T., Ogasawara, S., Uchida, K., Murao, S., Beyer, B.B., Dunn, B.M. and Oda, K. A CLN2-related and thermostable serine-carboxyl proteinase, kumamolysin: cloning, expression, and identification of catalytic serine residue. J. Biochem. 131 (2002) 757-765. [PMID: 11983085]

4. Comellas-Bigler, M., Fuentes-Prior, P., Maskos, K., Huber, R., Oyama, H., Uchida, K., Dunn, B.M., Oda, K. and Bode, W. The 1.4 a crystal structure of kumamolysin: a thermostable serine-carboxyl-type proteinase. Structure 10 (2002) 865-876. [PMID: 12057200]

5. Wlodawer, A., Li, M., Gustchina, A., Tsuruoka, N., Ashida, M., Minakata, H., Oyama, H., Oda, K., Nishino, T. and Nakayama, T. Crystallographic and biochemical investigations of kumamolisin-As, a serine-carboxyl peptidase with collagenase activity. J. Biol. Chem. 279 (2004) 21500-21510. [PMID: 15014068]

[EC 3.4.21.123 created 2023]

*EC 3.4.24.84

Accepted name: Ste24 endopeptidase

Reaction: Hydrolyses the peptide bond -P2-(S-farnesyl or geranylgeranyl)C-P1'-P2'-P3'-COOH where P1' and P2' are amino acids with aliphatic side chains and P3' is any C-terminal residue.

Comments: The enzyme hydrolyses proteins that terminate with a CaaX motif in which C is an S-isoprenylated cysteine residue, a is usually aliphatic and X is the C-terminal residue of the substrate protein, and may be any of several amino acids.The enzyme, which is the Type example of peptidase family M48, is one of two enzymes that can catalyse this processing step for mating a-factor in yeast. Subsequently, the S-isoprenylated cysteine residue that forms the new C-terminus is methyl-esterified and forms a hydrophobic membrane-anchor. Differs from EC 3.4.26.1, intramembrane prenyl-peptidase Rce1, in its catalytic mechanism and substrate preference.

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, MEROPS, PDB, CAS registry number: 148463-92-7

References:

1. Fujimura-Kamada, K., Nouvet, F.J. and Michaelis, S. A novel membrane-associated metalloprotease, Ste24p, is required for the first step of NH2-terminal processing of the yeast a-factor precursor. J. Cell Biol. 136 (1997) 271-285. [PMID: 9015299]

2. Tam, A., Schmidt, W.K. and Michaelis, S. The multispanning membrane protein Ste24p catalyzes CAAX proteolysis and NH2-terminal processing of the yeast a-factor precursor. J. Biol. Chem. 276 (2001) 46798-46806. [PMID: 11581258]

[EC 3.4.24.84 created 2003, modified 2023]

EC 3.4 Acting on peptide bonds (peptidases)

EC 3.4.26 Glutamic endopeptidases

EC 3.4.26.1

Accepted name: intramembrane prenyl-peptidase Rce1

Reaction: Hydrolyses the peptide bond -P2-(S-farnesyl or geranylgeranyl)C-P1'-P2'-P3'-COOH where where P1' and P2' are amino acids with aliphatic sidechains and P3' is any C-terminal residue.

Other name(s): CaaX prenyl protease 2; prenyl protein-specific endoprotease 2; PPSEP 2; α-factor-converting enzyme RCE1; ras converting enzyme; RACE; glutamic-type intramembrane endopeptidase Rce1; type II CAAX protease.

Comments: The cleavage site motif is typically referred to as CaaX, where the letter a represents any amino acid, rather than alanine, and X represents the C-terminal amino acid of the target protein. The enzyme has been found in the yeast Saccharomyces cerevisiae and homologues exist in humans and several other species. Although the cleavage site is similar to that of the metallo-peptidase Ste24 endopeptidase (EC 3.4.24.84), there appear to be specificity differences in the proteins hydrolysed by these two enzymes, with amino-acid substitution studies indicating activity of the yeast enzyme towards substrates with a hydrophylic residue at (P1') that are not hydrolysed by EC 3.4.24.84 [4].

References:

1. Otto, J.C., Kim, E., Young, S.G. and Casey, P.J. Cloning and characterization of a mammalian prenyl protein-specific protease. J. Biol. Chem. 274 (1999) 8379-8382. [PMID: 10085068]

2. Manolaridis, I., Kulkarni, K., Dodd, R.B., Ogasawara, S., Zhang, Z., Bineva, G., Reilly, N.O., Hanrahan, S.J., Thompson, A.J., Cronin, N., Iwata, S. and Barford, D. Mechanism of farnesylated CAAX protein processing by the intramembrane protease Rce1. Nature 504 (2013) 301-305. [PMID: 24291792]

3. Pei, J., Mitchell, D.A., Dixon, J.E. and Grishin, N.V. Expansion of type II CAAX proteases reveals evolutionary origin of γ-secretase subunit APH-1. J. Mol. Biol. 410 (2011) 18-26. [PMID: 21570408]

4. Trueblood, C.E., Boyartchuk, V.L., Picologlou, E.A., Rozema, D., Poulter, C.D. and Rine, J. The CaaX proteases, Afc1p and Rce1p, have overlapping but distinct substrate specificities. Mol. Cell Biol. 20 (2000) 4381-4392. [PMID: 10825201]

5. Plummer, L.J., Hildebrandt, E.R., Porter, S.B., Rogers, V.A., McCracken, J. and Schmidt, W.K. Mutational analysis of the ras converting enzyme reveals a requirement for glutamate and histidine residues. J. Biol. Chem. 281 (2006) 4596-4605. [PMID: 16361710]

[EC 3.4.26.1 created 2023]

EC 3.4.26.2

Accepted name: scytalidoglutamic peptidase

Reaction: Hydrolysis of proteins, with a strong preference for Phe or Tyr at position P1 and one of the smaller amino-acids at P1' in the sequence - P3 - P2 - P1 ┼P1'- P2'- P3'-. Cleaves the Tyr26-Thr27 bond in the B chain of oxidized insulin, which is not cleaved by pepsin.

Other name(s): scytalidopepsin-B; SCP-B; SGP; scytalidocarboxylpeptidase-B

Comments: The enzyme, isolated from the fungus Scytalidium lignicola and found in several other fungi, has a low pH optimum, being most active at pH 2 with casein as substrate. It differs from the pepsins (EC 3.4.23.1 and EC 3.4.23.2) in being insensitive to inhibition by pepstatin. It also differs from mammalian pepsins in showing a preference for a positively charged residue ( Lys or Arg) at the P3 position. In addition to the catalytic Glu residue, a Gln residue appears to play an important role in the hydrolytic mechanism. A member of peptidase family G01, the "eqolisin" family of glutamic peptidases (G01.0001).

References:

1. Kataoka, Y., Takada, K., Oyama, H., Tsunemi, M., James, M.N. and Oda, K. Catalytic residues and substrate specificity of scytalidoglutamic peptidase, the first member of the eqolisin in family (G1) of peptidases. FEBS Lett. 579 (2005) 2991-2994. [PMID: 15907842]

2. Fujinaga, M., Cherney, M.M., Oyama, H., Oda, K. and James, M.N. The molecular structure and catalytic mechanism of a novel carboxyl peptidase from Scytalidium lignicolum. Proc. Natl. Acad. Sci. USA 101 (2004) 3364-3369. [PMID: 14993599]

3. Pillai, B., Cherney, M.M., Hiraga, K., Takada, K., Oda, K. and James, M.N. Crystal structure of scytalidoglutamic peptidase with its first potent inhibitor provides insights into substrate specificity and catalysis. J. Mol. Biol. 365 (2007) 343-361. [PMID: 17069854]

4. Kondo, M.Y., Okamoto, D.N., Santos, J.A., Juliano, M.A., Oda, K., Pillai, B., James, M.N., Juliano, L. and Gouvea, I.E. Studies on the catalytic mechanism of a glutamic peptidase. J. Biol. Chem. 285 (2010) 21437-21445. [PMID: 20442413]

[EC 3.4.26.2 created 2023]

*EC 3.5.1.12

Accepted name: biotinidase

Reaction: biocytin + H2O = biotin + L-lysine

Glossary: biocytin = ε-N-biotinyl-L-lysine

Other name(s): amidohydrolase biotinidase; biocytinase; biotin-amide amidohydrolase

Systematic name: biocytin amidohydrolase

Comments: The enzyme, found in many bacterial species as well as animals, liberates biotin from biocytin and short biotinylated peptides, but not from biotinylated proteins. It also has activity on biotin esters and biotin amides.

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 9025-15-4

References:

1. Thoma, R.W. and Peterson, W.H. The enzymatic degradation of soluble bound biotin. J. Biol. Chem. 210 (1954) 569-579. [PMID: 13211594]

2. Knappe, J., Brümer, W. and Biederbick, K. Reinigung und Eigenschaften der Biotinidase aus Schweinenieren und Lactobacillus casei. Biochem. Z. 338 (1963) 599-613. [PMID: 14087327]

3. Pispa, J. and Koivusalo, M. Actinomycin D-sensitive increase in the biotinidase activity in mouse liver and serum after ethionine feeding. Acta Chem. Scand. 26 (1972) 2133-2135. [PMID: 5081874]

[EC 3.5.1.12 created 1961, modified 2023]

EC 3.8.2.2

Accepted name: diisopropyl-fluorophosphatase

Reaction: diisopropyl fluorophosphate + H2O = diisopropyl phosphate + fluoride

Other name(s): DFPase; tabunase; somanase; organophosphorus acid anhydrolase; organophosphate acid anhydrase; OPA anhydrase (ambiguous); diisopropylphosphofluoridase; dialkylfluorophosphatase; diisopropyl phosphorofluoridate hydrolase; isopropylphosphorofluoridase; diisopropylfluorophosphonate dehalogenase

Systematic name: diisopropyl-fluorophosphate fluorohydrolase

Comments: Acts on phosphorus anhydride bonds (such as phosphorus-halide and phosphorus-cyanide) in organophosphorus compounds (including ‘nerve gases’). Inhibited by chelating agents; requires divalent cations. Related to EC 3.1.8.1 aryldialkylphosphatase.

References:

1. Augustinsson, K.-B. and Heimburger, G. Enzymatic hydrolysis of organophosphorus compounds. I. Occurrence of enzymes hydrolysing dimethyl-amido-ethoxy-phosphoryl cyanide (Tabun). Acta Chem. Scand. 8 (1954) 753-761.

2. Augustinsson, K.-B. and Heimburger, G. Enzymatic hydrolysis of organophosphorus compounds. II. Analysis of reaction products in experiments with Tabun and some properties of blood plasma tabunase. Acta Chem. Scand. 8 (1954) 762-767.

3. Augustinsson, K.-B. and Heimburger, G. Enzymatic hydrolysis of organophosphorus compounds. IV. Specificity studies. Acta Chem. Scand. 8 (1954) 1533-1541.

4. Cohen, J.A. and Warringa, M.G.P.J. Purification and properties of dialkylfluorophosphatase. Biochim. Biophys. Acta 26 (1957) 29-39. [PMID: 13479457]

5. Mounter, L.A. Enzymic hydrolysis of organophosphorus compounds. In: Boyer, P.D., Lardy, H. and Myrbäck, K. (Ed.), The Enzymes, 2nd edn, vol. 4, Academic Press, New York, 1960, pp. 541-550.

6. Reiner, E., Aldridge, W.N. and Hoskin, C.G. (Ed.), Enzymes Hydrolysing Organophosphorus Compounds, Ellis Horwood, Chichester, UK, 1989.

[EC 3.8.2.2 created 1961 as EC 3.8.2.1, transferred 1992 to EC 3.1.8.2, reinstated 2023 as EC 3.8.2.1]

*EC 4.1.1.87

Accepted name: malonyl-[malonate decarboxylase] decarboxylase

Reaction: a malonyl-[holo malonate decarboxylase acyl-carrier protein] = an acetyl-[holo malonate decarboxylase acyl-carrier protein] + CO2

For diagram of reaction, click here

Other name(s): malonyl-S-ACP decarboxylase; malonyl-S-acyl-carrier protein decarboxylase; MdcD/MdcE; MdcD,E; malonyl-[acyl-carrier-protein] carboxy-lyase

Systematic name: malonyl-[holo malonate decarboxylase acyl-carrier protein] carboxy-lyase

Comments: This enzyme comprises the β and γ subunits of EC 4.1.1.88, biotin-independent malonate decarboxylase but is not present in EC 7.2.4.4, biotin-dependent malonate decarboxylase. It follows on from EC 2.3.1.187, acetyl-S-ACP:malonate ACP transferase, and results in the regeneration of the acetylated form of the acyl-carrier-protein subunit of malonate decarboxylase [5]. The carboxy group is lost with retention of configuration [3].

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:

References:

1. Schmid, M., Berg, M., Hilbi, H. and Dimroth, P. Malonate decarboxylase of Klebsiella pneumoniae catalyses the turnover of acetyl and malonyl thioester residues on a coenzyme-A-like prosthetic group. Eur. J. Biochem. 237 (1996) 221-228. [PMID: 8620876]

2. Koo, J.H. and Kim, Y.S. Functional evaluation of the genes involved in malonate decarboxylation by Acinetobacter calcoaceticus. Eur. J. Biochem. 266 (1999) 683-690. [PMID: 10561613]

3. Handa, S., Koo, J.H., Kim, Y.S. and Floss, H.G. Stereochemical course of biotin-independent malonate decarboxylase catalysis. Arch. Biochem. Biophys. 370 (1999) 93-96. [PMID: 10496981]

4. Chohnan, S., Akagi, K. and Takamura, Y. Functions of malonate decarboxylase subunits from Pseudomonas putida. Biosci. Biotechnol. Biochem. 67 (2003) 214-217. [PMID: 12619701]

5. Dimroth, P. and Hilbi, H. Enzymic and genetic basis for bacterial growth on malonate. Mol. Microbiol. 25 (1997) 3-10. [PMID: 11902724]

[EC 4.1.1.87 created 2008, modified 2023]

EC 4.1.1.124

Accepted name: malonyl-[acp] decarboxylase

Reaction: malonyl-[acp] = acetyl-[acp] + CO2

Other name(s): decarboxylative ketosynthase; bryQ (gene name); mupG (gene name); pksF (gene name); curC (gene name); jamG (gene name); pedM (gene name)

Systematic name: malonyl-[acyl-carrier protein] carboxy-lyase

Comments: This family of enzymes participates in a process that introduces a methyl branch into nascent polyketide products. The process begins with EC 4.1.1.124, malonyl-[acp] decarboxylase, which converts the common extender unit malonyl-[acp] to acetyl-[acp]. The enzyme is a mutated form of a ketosynthase enzyme, in which a Cys residue in the active site is modified to a Ser residue, leaving the decarboxylase function intact, but nulifying the ability of the enzyme to form a carbon-carbon bond. Next, EC 2.3.3.22, 3-carboxymethyl-3-hydroxy-acyl-[acp] synthase, utilizes the acetyl group to introduce the branch at the β position of 3-oxoacyl intermediates attached to a polyketide synthase, forming a 3-hydroxy-3-carboxymethyl intermediate. This is followed by dehydration catalysed by EC 4.2.1.181, 3-carboxymethyl-3-hydroxy-acyl-[acp] dehydratase (often referred to as an ECH1 domain), leaving a 3-carboxymethyl group and forming a double bond between the α and β carbons. The process concludes with decarboxylation catalysed by EC 4.1.1.125, 4-carboxy-3-alkylbut-2-enoyl-[acp] decarboxylase (often referred to as an ECH2 domain), leaving a methyl branch at the β carbon. The enzymes are usually encoded by a cluster of genes referred to as an "HMGS cassette", based on the similarity of the key enzyme to EC 2.3.3.10, hydroxymethylglutaryl-CoA synthase. cf. EC 4.1.1.87, malonyl-[malonate decarboxylase] decarboxylase.

References:

1. Simunovic, V. and Muller, R. 3-hydroxy-3-methylglutaryl-CoA-like synthases direct the formation of methyl and ethyl side groups in the biosynthesis of the antibiotic myxovirescin A. Chembiochem 8 (2007) 497-500. [PMID: 17330904]

2. Wu, J., Hothersall, J., Mazzetti, C., O'Connell, Y., Shields, J.A., Rahman, A.S., Cox, R.J., Crosby, J., Simpson, T.J., Thomas, C.M. and Willis, C.L. In vivo mutational analysis of the mupirocin gene cluster reveals labile points in the biosynthetic pathway: the "leaky hosepipe" mechanism. Chembiochem 9 (2008) 1500-1508. [PMID: 18465759]

3. Buchholz, T.J., Rath, C.M., Lopanik, N.B., Gardner, N.P., Hakansson, K. and Sherman, D.H. Polyketide β-branching in bryostatin biosynthesis: identification of surrogate acetyl-ACP donors for BryR, an HMG-ACP synthase. Chem. Biol. 17 (2010) 1092-1100. [PMID: 21035732]

[EC 4.1.1.124 created 2023]

EC 4.1.1.125

Accepted name: 4-carboxy-3-alkylbut-2-enoyl-[acp] decarboxylase

Reaction: a 4-carboxy-3-alkylbut-2-enoyl-[acp] = a 3-alkylbut-2-enoyl-[acp] + CO2

Other name(s): aprG (gene name); corG (gene name); pedI (gene name); mupK (gene name); 3-carboxymethyl-alk-2-enyl-[acyl-carrier protein] decarboxylase

Systematic name: 4-carboxy-3-alkylbut-2-enoyl-[acyl-carrier protein] carboxy-lyase

Comments: This family of enzymes participates in a process that introduces a methyl branch into nascent polyketide products. The process begins with EC 4.1.1.124, malonyl-[acp] decarboxylase, which converts the common extender unit malonyl-[acp] to acetyl-[acp]. The enzyme is a mutated form of a ketosynthase enzyme, in which a Cys residue in the active site is modified to a Ser residue, leaving the decarboxylase function intact, but nulifying the ability of the enzyme to form a carbon-carbon bond. Next, EC 2.3.3.22, 3-carboxymethyl-3-hydroxy-acyl-[acp] synthase, utilizes the acetyl group to introduce the branch at the β position of 3-oxoacyl intermediates attached to a polyketide synthase, forming a 3-hydroxy-3-carboxymethyl intermediate. This is followed by dehydration catalysed by EC 4.2.1.181, 3-carboxymethyl-3-hydroxy-acyl-[acp] dehydratase (often referred to as an ECH1 domain), leaving a 3-carboxymethyl group and forming a double bond between the α and β carbons. The process concludes with decarboxylation catalysed by EC 4.1.1.125, 4-carboxy-3-alkylbut-2-enoyl-[acp] decarboxylase (often referred to as an ECH2 domain), leaving a methyl branch at the β carbon. The enzymes are usually encoded by a cluster of genes referred to as an "HMGS cassette", based on the similarity of the key enzyme to EC 2.3.3.10, hydroxymethylglutaryl-CoA synthase.

References:

1. Geders, T.W., Gu, L., Mowers, J.C., Liu, H., Gerwick, W.H., Hakansson, K., Sherman, D.H. and Smith, J.L. Crystal structure of the ECH2 catalytic domain of CurF from Lyngbya majuscula. Insights into a decarboxylase involved in polyketide chain β-branching. J. Biol. Chem. 282 (2007) 35954-35963. [PMID: 17928301]

2. Erol, O., Schaberle, T.F., Schmitz, A., Rachid, S., Gurgui, C., El Omari, M., Lohr, F., Kehraus, S., Piel, J., Muller, R. and Konig, G.M. Biosynthesis of the myxobacterial antibiotic corallopyronin A. Chembiochem 11 (2010) 1253-1265. [PMID: 20503218]

3. Grindberg, R.V., Ishoey, T., Brinza, D., Esquenazi, E., Coates, R.C., Liu, W.T., Gerwick, L., Dorrestein, P.C., Pevzner, P., Lasken, R. and Gerwick, W.H. Single cell genome amplification accelerates identification of the apratoxin biosynthetic pathway from a complex microbial assemblage. PLoS One 6 (2011) e18565. [PMID: 21533272]

[EC 4.1.1.125 created 2023]

EC 4.1.1.126

Accepted name: anhydromevalonate phosphate decarboxylase

Reaction: trans-anhydromevalonate 5-phosphate = 3-methylbut-3-en-1-yl phosphate + CO2

Glossary: trans-anhydromevalonate 5-phosphate = (2E)-3-methyl-5-phosphooxypent-2-enoate
3-methylbut-3-en-1-yl phosphate = isopentenyl phosphate

Systematic name: trans-anhydromevalonate 5-phosphate carboxy-lyase

Comments: The enzyme catalyses a step in the archaeal prenyl diphosphate biosynthesis pathway. It requires a prenylated flavin cofactor that is produced by EC 2.5.1.129, flavin prenyltransferase.

References:

1. Yoshida, R., Yoshimura, T. and Hemmi, H. Reconstruction of the "archaeal" mevalonate pathway from the methanogenic archaeon Methanosarcina mazei in Escherichia coli cells. Appl. Environ. Microbiol. 86 (2020) e02889-19. [PMID: 31924615]

[EC 4.1.1.126 created 2023]

EC 4.2.1.181

Accepted name: 3-carboxymethyl-3-hydroxy-acyl-[acp] dehydratase

Reaction: a 3-carboxymethyl-3-hydroxy-acyl-[acyl-carrier protein] = a 4-carboxy-3-alkylbut-2-enoyl-[acyl-carrier protein] + H2O

Other name(s): aprF (gene name); corF (gene name); curE (gene name); pedL (gene name); 3-carboxymethyl-3-hydroxy-acyl-[acyl-carrier protein] dehydratase

Systematic name: 3-carboxymethyl-3-hydroxy-acyl-[acyl-carrier protein] hydro-lyase

Comments: This family of enzymes participates in a process that introduces a methyl branch into nascent polyketide products. The process begins with EC 4.1.1.124, malonyl-[acp] decarboxylase, which converts the common extender unit malonyl-[acp] to acetyl-[acp]. The enzyme is a mutated form of a ketosynthase enzyme, in which a Cys residue in the active site is modified to a Ser residue, leaving the decarboxylase function intact, but nulifying the ability of the enzyme to form a carbon-carbon bond. Next, EC 2.3.3.22, 3-carboxymethyl-3-hydroxy-acyl-[acp] synthase, utilizes the acetyl group to introduce the branch at the β position of 3-oxoacyl intermediates attached to a polyketide synthase, forming a 3-hydroxy-3-carboxymethyl intermediate. This is followed by dehydration catalysed by EC 4.2.1.181, 3-carboxymethyl-3-hydroxy-acyl-[acp] dehydratase (often referred to as an ECH1 domain), leaving a 3-carboxymethyl group and forming a double bond between the α and β carbons. The process concludes with decarboxylation catalysed by EC 4.1.1.125, 4-carboxy-3-alkylbut-2-enoyl-[acp] decarboxylase (often referred to as an ECH2 domain), leaving a methyl branch at the β carbon. The enzymes are usually encoded by a cluster of genes referred to as an "HMGS cassette", based on the similarity of the key enzyme to EC 2.3.3.10, hydroxymethylglutaryl-CoA synthase. cf. EC 4.2.1.18, methylglutaconyl-CoA hydratase.

References:

1. Gu, L., Jia, J., Liu, H., Hakansson, K., Gerwick, W.H. and Sherman, D.H. Metabolic coupling of dehydration and decarboxylation in the curacin A pathway: functional identification of a mechanistically diverse enzyme pair. J. Am. Chem. Soc. 128 (2006) 9014-9015. [PMID: 16834357]

2. Gu, L., Wang, B., Kulkarni, A., Geders, T.W., Grindberg, R.V., Gerwick, L., Hakansson, K., Wipf, P., Smith, J.L., Gerwick, W.H. and Sherman, D.H. Metamorphic enzyme assembly in polyketide diversification. Nature 459 (2009) 731-735. [PMID: 19494914]

3. Erol, O., Schaberle, T.F., Schmitz, A., Rachid, S., Gurgui, C., El Omari, M., Lohr, F., Kehraus, S., Piel, J., Muller, R. and Konig, G.M. Biosynthesis of the myxobacterial antibiotic corallopyronin A. Chembiochem 11 (2010) 1253-1265. [PMID: 20503218]

4. Grindberg, R.V., Ishoey, T., Brinza, D., Esquenazi, E., Coates, R.C., Liu, W.T., Gerwick, L., Dorrestein, P.C., Pevzner, P., Lasken, R. and Gerwick, W.H. Single cell genome amplification accelerates identification of the apratoxin biosynthetic pathway from a complex microbial assemblage. PLoS One 6 (2011) e18565. [PMID: 21533272]

[EC 4.2.1.181 created 2023]

EC 4.2.1.182

Accepted name: phosphomevalonate dehydratase

Reaction: (R)-5-phosphomevalonate = trans-anhydromevalonate 5-phosphate + H2O

Glossary: trans-anhydromevalonate 5-phosphate = (2E)-3-methyl-5-phosphooxypent-2-enoate

Systematic name: R-5-phosphomevalonate hydro-lyase

Comments: The enzyme catalyses a step in an archaeal prenyl diphosphate biosynthesis pathway. It belongs to the aconitase X family, and contains a [4Fe-4S] cluster.

References:

1. Yoshida, R., Yoshimura, T. and Hemmi, H. Reconstruction of the "archaeal" mevalonate pathway from the methanogenic archaeon Methanosarcina mazei in Escherichia coli Cells. Appl. Environ. Microbiol. 86 (2020) e02889-19. [PMID: 31924615]

2. Komeyama, M., Kanno, K., Mino, H., Yasuno, Y., Shinada, T., Ito, T. and Hemmi, H. A [4Fe-4S] cluster resides at the active center of phosphomevalonate dehydratase, a key enzyme in the archaeal modified mevalonate pathway. Front Microbiol. 14 (2023) 1150353. [PMID: 36992929]

[EC 4.2.1.182 created 2023]

EC 4.2.2.29

Accepted name: peptidoglycan lytic transglycosylase

Reaction: a peptidoglycan chain = a peptidoglycan chain with N-acetyl-1,6-anhydromuramyl-(peptide) at the reducing end + a peptidoglycan chain with N-acetylglucosamine at the non-reducing end

Other name(s): lytic murein transglycosylase; endolytic murein transglycosylase; lytic transglycosylase; endolytic transglycosylase; MtlA; MltB; MltC; MltD; MltE; MltF; MltG; Slt; RlpA; SleB; SpoIID

Systematic name: peptidoglycan N-acetylmuramate—N-acetyl-β-D-glucosamine lyase

Comments: A group of bacterial enzymes that catalyse the non-hydrolytic cleavage of peptidoglycan (PG). The enzymes fragment the polysaccharide chain at the β-1,4-glycosidic bond between N-acetylmuramic acid and N-acetylglucosamine residues by an intramolecular cyclization of the N-acetylmuramyl moiety to yield a 1,6-anhydro-N-acetyl-β-D-muramyl product. Includes endolytic transglycosylase activity that fragments the glycan chain internally and exolytic transgylcosylase activity that cleaves a terminal disaccharide from the end of the glycan strand. The MtlG enzyme of Gram-negative bacteria may function to regulate glycan strand length within the PG polymer.

References:

1. Holtje, J.V., Mirelman, D., Sharon, N. and Schwarz, U. Novel type of murein transglycosylase in Escherichia coli. J. Bacteriol. 124 (1975) 1067-1076. [PMID: 357]

2. Yunck, R., Cho, H. and Bernhardt, T.G. Identification of MltG as a potential terminase for peptidoglycan polymerization in bacteria. Mol. Microbiol. 99 (2016) 700-718. [PMID: 26507882]

3. Dik, D.A., Marous, D.R., Fisher, J.F. and Mobashery, S. Lytic transglycosylases: concinnity in concision of the bacterial cell wall. Crit. Rev. Biochem. Mol. Biol. 52 (2017) 503-542. [PMID: 28644060]

[EC 4.2.2.29 created 2023]

EC 4.2.3.212

Accepted name: (+)-δ-cadinol synthase

Reaction: (2E,6E)-farnesyl diphosphate + H2O = (+)-δ-cadinol + diphosphate

For diagram of reaction click here

Glossary: (+)-δ-cadinol = (1S,4R,4aS,8aR)-1,6-dimethyl-4-(propan-2-yl)-1,2,3,4,4a,7,8,8a-octahydronaphthalen-1-ol = (+)-torreyol

Other name(s): δ-cadinol synthase (ambiguous)

Systematic name: (2E,6E)-farnesyl-diphosphate diphosphate-lyase [(+)-δ-cadinol-forming]

Comments: The enzyme is involved in the biosynthesis of sesquiterpenoids from (2E,6E)-farnesyl-diphosphate diphosphate in fungi such as Boreostereum vibrans and Coniophora puteana

References:

1. Zhou, H., Yang, Y.L., Zeng, J., Zhang, L., Ding, Z.H. and Zeng, Y. Identification and characterization of a δ-cadinol synthase potentially involved in the formation of boreovibrins in Boreostereum vibrans of basidiomycota. Nat. Prod. Bioprospect. 6 (2016) 167-171. [PMID: 27038475]

2. Ringel, M., Dimos, N., Himpich, S., Haack, M., Huber, C., Eisenreich, W., Schenk, G., Loll, B. and Bruck, T. Biotechnological potential and initial characterization of two novel sesquiterpene synthases from Basidiomycota Coniophora puteana for heterologous production of δ-cadinol. Microb. Cell Fact. 21 (2022) 64. [PMID: 35440053]

[EC 4.2.3.212 created 2023]

EC 4.2.3.213

Accepted name: colleterpenol synthase

Reaction: all-trans-hexaprenyl diphosphate + H2O = colleterpenol + diphosphate

Glossary: colleterpenol = (2S)-2-[(1R,3E,7E,11E)-4,8,12-trimethylcyclotetradeca-3,7,11-trien-1-yl]undeca-5,9-dien-2-ol

Other name(s): CgCS

Systematic name: pentaprenyl-diphosphate diphosphate-lyase [cyclizing, colleterpenol-forming]

Comments: Isolated from Colletotrichum gloeosporioides, a pathogenic fungus that causes bitter rot in variety of crops.

References:

1. Tao, H., Lauterbach, L., Bian, G., Chen, R., Hou, A., Mori, T., Cheng, S., Hu, B., Lu, L., Mu, X., Li, M., Adachi, N., Kawasaki, M., Moriya, T., Senda, T., Wang, X., Deng, Z., Abe, I., Dickschat, J.S. and Liu, T. Discovery of non-squalene triterpenes. Nature 606 (2022) 414-419. [PMID: 35650436]

[EC 4.2.3.213 created 2023]

EC 4.2.3.214

Accepted name: dolasta-1(15),8-diene synthase

Reaction: geranylgeranyl diphosphate = (5R,12R,14S)-dolasta-1(15),8-diene + diphosphate

For diagram of reaction click here

Glossary: (5R,12R,14S)-dolasta-1(15),8-diene = (3aR,4aS,8aR)-3a,8a-dimethyl-5-methylene-1-(propan-2-yl)-2,3,3a,4,4a,5,6,7,8,8a,9,10-dodecahydrobenzo[f]azulene

Other name(s): Cg113742 (gene name); CgDS

Systematic name: geranylgeranyl-diphosphate diphosphate-lyase [cyclizing, dolasta-1(15),8-diene-forming]

Comments: Isolated from Colletotrichum gloeosporioides, a pathogenic fungus that causes bitter rot in variety of crops.

References:

1. Bian, G., Rinkel, J., Wang, Z., Lauterbach, L., Hou, A., Yuan, Y., Deng, Z., Liu, T. and Dickschat, J.S. A clade II-D fungal chimeric diterpene synthase from Colletotrichum gloeosporioides produces dolasta-1(15),8-diene. Angew. Chem. Int. Ed. Engl. 57 (2018) 15887-15890. [PMID: 30277637]

[EC 4.2.3.214 created 2023]

EC 4.2.3.215

Accepted name: δ-araneosene synthase

Reaction: geranylgeranyl diphosphate = δ-araneosene + diphosphate

For diagram of reaction click here

Glossary: δ-araneosene = (3aR,5E,9E)-3a,6,10-trimethyl-1-(propan-2-yl)-2,3,3a,4,7,8,11,12-octahydrocyclopenta[11]annulene

Systematic name: geranylgeranyl-diphosphate diphosphate-lyase [cyclizing, δ-araneosene-forming]

Comments: Isolated from the fungus Colletotrichum gloeosporioidea. δ-Araneosene may be involved in the biosynthesis of dolasta-1(15),8-diene (see EC 4.2.3.214, dolasta-1(15),8-diene synthase) and cycloaraneosene (see EC 4.2.3.191, cycloaraneosene synthase).

References:

1. Bian, G., Rinkel, J., Wang, Z., Lauterbach, L., Hou, A., Yuan, Y., Deng, Z., Liu, T. and Dickschat, J.S. A clade II-D fungal chimeric diterpene synthase from Colletotrichum gloeosporioides produces dolasta-1(15),8-diene. Angew. Chem. Int. Ed. Engl. 57 (2018) 15887-15890. [PMID: 30277637]

[EC 4.2.3.215 created 2023]

EC 4.2.3.216

Accepted name: somaliensene A synthase

Reaction: geranylfarnesyl diphosphate = somaliensene A + diphosphate

For diagram of reaction click here

Glossary: somaliensene A = (1S,5R,6R)-6-methyl-6-[(3E,7E,11E)-trimethyltrideca-3,7,11-trien-1-yl]bicyclo[3.1.1]hept-2-ene

Other name(s): stsC (gene name)

Systematic name: geranylfarnesyl-diphosphate diphosphate-lyase (cyclizing, somaliensene A-forming)

Comments: A sesterterpenoid synthase enzyme isolated from the bacterium Streptomyces somaliensis. The enzyme also produces somalensene B (cf. EC 4.2.3.217, somaliensene B synthase).

References:

1. Yang, Y., Zhang, Y., Zhang, S., Chen, Q., Ma, K., Bao, L., Tao, Y., Yin, W., Wang, G. and Liu, H. Identification and characterization of a membrane-bound sesterterpene cyclase from Streptomyces somaliensis. J Nat Prod 81 (2018) 1089-1092. [PMID: 29553734]

[EC 4.2.3.216 created 2023]

EC 4.2.3.217

Accepted name: somaliensene B synthase

Reaction: geranylfarnesyl diphosphate = somaliensene B + diphosphate

For diagram of reaction click here

Glossary: somaliensene B = (4S)-1-methyl-4-[(5E,9E,13E)-6,10,14-trimethylpentadeca-1,5,9,13-tetraen-2-yl]cyclohex-1-ene

Other name(s): stsC (gene name)

Systematic name: geranylfarnesyl-diphosphate diphosphate-lyase (cyclizing, somaliensene B-forming)

Comments: A sesterterpenoid synthase enzyme isolated from the bacterium Streptomyces somaliensis. The enzyme also produces somaliensene A (cf. EC 4.2.3.216, somaliensene A synthase).

References:

1. Yang, Y., Zhang, Y., Zhang, S., Chen, Q., Ma, K., Bao, L., Tao, Y., Yin, W., Wang, G. and Liu, H. Identification and characterization of a membrane-bound sesterterpene cyclase from Streptomyces somaliensis. J Nat Prod 81 (2018) 1089-1092. [PMID: 29553734]

[EC 4.2.3.217 created 2023]

EC 4.2.3.218

Accepted name: variediene synthase

Reaction: geranylgeranyl diphosphate = variediene + diphosphate

For diagram of reaction click here

Glossary: variediene = (3aR,3bS,6E,10Z,11aR)-3,3,6,10,11a-pentamethyl-2,3,3a,3b,4,5,8,9,11,11a-decahydro-1H-cyclonona[a]pentalene

Other name(s): EvVS

Systematic name: geranylgeranyl-diphosphate diphosphate-lyase (cyclizing, variediene-forming)

Comments: A diterpenoid synthase enzyme isolated from the fungus Aspergillus stellatus.

References:

1. Qin, B., Matsuda, Y., Mori, T., Okada, M., Quan, Z., Mitsuhashi, T., Wakimoto, T. and Abe, I. An unusual chimeric diterpene synthase from Emericella variecolor and its functional conversion into a sesterterpene synthase by domain swapping. Angew. Chem. Int. Ed. Engl. 55 (2016) 1658-1661. [PMID: 26546087]

[EC 4.2.3.218 created 2023]

EC 4.2.3.219

Accepted name: (2E)-α-cericerene synthase

Reaction: geranylfarnesyl diphosphate = (2E)-α-cericerene + diphosphate

For diagram of reaction click here

Glossary: (2E)-α-cericerene = (1E,4R,7E,11E)-1,7,11-trimethyl-4-[(2E)-6-methylhepta-2,5-dien-2-yl]cyclotetrdeca-1,7,11-triene

Other name(s): EvSS

Systematic name: geranylfarneyl-diphosphate diphosphate-lyase (cyclizing, (2E)-α-cericerene-forming)

Comments: A sesterterpenoid synthase enzyme isolated from the fungus Aspergillus stellatus.

References:

1. Qin, B., Matsuda, Y., Mori, T., Okada, M., Quan, Z., Mitsuhashi, T., Wakimoto, T. and Abe, I. An unusual chimeric diterpene synthase from Emericella variecolor and its functional conversion into a sesterterpene synthase by domain swapping. Angew. Chem. Int. Ed. Engl. 55 (2016) 1658-1661. [PMID: 26546087]

[EC 4.2.3.219 created 2023]

EC 6.7.1.2

Accepted name: 3-aminoavenalumate diazotase

Reaction: ATP + 3-aminoavenalumate + nitrite = AMP + diphosphate + 3-diazoavenalumate + H2O

Glossary: 3-aminoavenalumate = (2E,4E)-5-(3-amino-4-hydroxyphenyl)penta-2,4-dienoate
3-diazoavenalumate = 1-{3-[(1E,3E)-4-carboxylatobuta-1,3-dien-1-yl]-6-oxocyclohexa-2,4-dien-1-ylidene}diazenium

Other name(s): avaA6 (gene name)

Systematic name: 3-aminoavenalumate:nitrite ligase (AMP-forming)

Comments: The enzyme, characterized from the bacterium Streptomyces sp. RI-77, participates in the biosynthesis of avenalumate, a phenolic acid originally described from oat (Avena sativa). It can also act on 3-aminocoumarate and 3-amino-4-hydroxybenzoate with lower activity.

References:

1. Kawai, S., Hagihara, R., Shin-Ya, K., Katsuyama, Y. and Ohnishi, Y. Bacterial avenalumic acid biosynthesis includes substitution of an aromatic amino group for hydride by nitrous acid dependent diazotization. Angew. Chem. Int. Ed. Engl. 61 (2022) e202211728. [PMID: 36115045]

[EC 6.7.1.2 created 2023]

*EC 7.1.1.3

Accepted name: ubiquinol oxidase (H+-transporting)

Reaction: 2 quinol + O2[side 2] + 8 H+[side 2] = 2 quinone + 2 H2O[side 2] + 8 H+[side 1]

Other name(s): cyoABCD (gene names); cytochrome bo3 oxidase; cytochrome bb3 oxidase; cytochrome bo oxidase; Cyo oxidase; ubiquinol:O2 oxidoreductase (H+-transporting); ubiquinol:oxygen oxidoreductase (H+-transporting)

Systematic name: quinol:oxygen oxidoreductase (H+-transporting)

Comments: Contains a dinuclear centre comprising heme and copper. This terminal oxidase enzyme generates proton motive force by two mechanisms: (1) transmembrane charge separation resulting from utilizing protons and electrons originating from opposite sides of the membrane to generate water, and (2) active pumping of protons across the membrane. The bioenergetic efficiency (the number of charges driven across the membrane per electron used to reduce oxygen to water) of enzymes that have been characterized so far is 2. cf. EC 7.1.1.7, ubiquinol oxidase ubiquinol oxidase (electrogenic, proton-motive force generating).

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number:

References:

1. Miyoshi-Akiyama, T., Hayashi, M. and Unemoto, T. Purification and properties of cytochrome bo-type ubiquinol oxidase from a marine bacterium Vibrio alginolyticus. Biochim. Biophys Acta 1141 (1993) 283-287. [PMID: 8443214]

2. de Gier, J.W., Lubben, M., Reijnders, W.N., Tipker, C.A., Slotboom, D.J., van Spanning, R.J., Stouthamer, A.H. and van der Oost, J. The terminal oxidases of Paracoccus denitrificans. Mol. Microbiol. 13 (1994) 183-196. [PMID: 7984100]

3. Howitt, C.A. and Vermaas, W.F. Quinol and cytochrome oxidases in the cyanobacterium Synechocystis sp. PCC 6803. Biochemistry 37 (1998) 17944-17951. [PMID: 9922162]

4. Abramson, J., Riistama, S., Larsson, G., Jasaitis, A., Svensson-Ek, M., Laakkonen, L., Puustinen, A., Iwata, S. and Wikstrom, M. The structure of the ubiquinol oxidase from Escherichia coli and its ubiquinone binding site. Nat. Struct. Biol. 7 (2000) 910-917. [PMID: 11017202]

5. Morales, G., Ugidos, A. and Rojo, F. Inactivation of the Pseudomonas putida cytochrome o ubiquinol oxidase leads to a significant change in the transcriptome and to increased expression of the CIO and cbb3-1 terminal oxidases. Environ. Microbiol. 8 (2006) 1764-1774. [PMID: 16958757]

6. Stenberg, F., von Heijne, G. and Daley, D.O. Assembly of the cytochrome bo3 complex. J. Mol. Biol. 371 (2007) 765-773. [PMID: 17583738]

7. Yap, L.L., Lin, M.T., Ouyang, H., Samoilova, R.I., Dikanov, S.A. and Gennis, R.B. The quinone-binding sites of the cytochrome bo3 ubiquinol oxidase from Escherichia coli. Biochim. Biophys. Acta 1797 (2010) 1924-1932. [PMID: 20416270]

8. Choi, S.K., Lin, M.T., Ouyang, H. and Gennis, R.B. Searching for the low affinity ubiquinone binding site in cytochrome bo3 from Escherichia coli. Biochim Biophys Acta Bioenerg 1858 (2017) 366-370. [PMID: 28235459]

9. Choi, S.K., Schurig-Briccio, L., Ding, Z., Hong, S., Sun, C. and Gennis, R.B. Location of the Substrate Binding Site of the Cytochrome bo3 Ubiquinol Oxidase from Escherichia coli. J. Am. Chem. Soc. 139 (2017) 8346-8354. [PMID: 28538096]

10. Graf, S., Brzezinski, P. and von Ballmoos, C. The proton pumping bo oxidase from Vitreoscilla. Sci. Rep. 9 (2019) 4766. [PMID: 30886219]

[EC 7.1.1.3 created 2011 as EC 1.10.3.10, modified 2014, transferred 2018 to EC 7.1.1.3, modified 2023]


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