Reaction: 3 malonyl-CoA = phloroglucinol + 3 CO2 + 3 CoA
For diagram of reaction click here.
Glossary: phloroglucinol = 1,3,5-trihydroxybenzene
Other name(s): phlD (gene name)
Systematic name: malonyl-CoA:malonyl-CoA malonyltransferase (decarboxylating, phloroglucinol-forming)
Comments: The enzyme, characterized from the bacterium Pseudomonas protegens Pf-5, is a type III polyketide synthase. The mechanism involves the cyclization of an activated 3,5-dioxoheptanedioate intermediate. The enzyme exhibits broad substrate specificity, and can accept C4-C12 aliphatic acyl-CoAs and phenylacetyl-CoA as the starter molecules, forming 6-(polyoxoalkylated)-α-pyrones by sequential condensation with malonyl-CoA.
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:
1. Achkar, J., Xian, M., Zhao, H. and Frost, J.W. Biosynthesis of phloroglucinol. J. Am. Chem. Soc. 127 (2005) 5332-5333.
2. Zha, W., Rubin-Pitel, S.B. and Zhao, H. Characterization of the substrate specificity of PhlD, a type III polyketide synthase from Pseudomonas fluorescens. J. Biol. Chem. 281 (2006) 32036-32047. [PMID: 16931521]