Reaction: ATP + hydrogenobyrinic acid a,c-diamide + Co2+ + H2O = ADP + phosphate + cob(II)yrinic acid a,c-diamide + H+
For diagram click here.
Other name(s): hydrogenobyrinic acid a,c-diamide cobaltochelatase; CobNST; CobNCobST
Systematic name: hydrogenobyrinic-acid-a,c-diamide:cobalt cobalt-ligase (ADP-forming)
Comments: This enzyme, which forms part of the aerobic cobalamin biosynthesis pathway, is a type I chelatase, being heterotrimeric and ATP-dependent. It comprises two components, one of which corresponds to CobN and the other is composed of two polypeptides, specified by cobS and cobT in Pseudomonas denitrificans, and named CobST . Hydrogenobyrinic acid is a very poor substrate. ATP can be replaced by dATP or CTP but the reaction proceeds more slowly. CobN exhibits a high affinity for hydrogenobyrinic acid a,c-diamide. The oligomeric protein CobST possesses at least one sulfhydryl group that is essential for ATP-binding. Once the Co2+ is inserted, the next step in the pathway ensures that the cobalt is ligated securely by reducing Co(II) to Co(I). This step is carried out by EC 22.214.171.124, cob(II)yrinic acid a,c-diamide reductase.
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number: 81295-49-0
1. Debussche, L., Couder, M., Thibaut, D., Cameron, B., Crouzet, J. and Blanche, F. Assay, purification, and characterization of cobaltochelatase, a unique complex enzyme catalyzing cobalt insertion in hydrogenobyrinic acid a,c-diamide during coenzyme B12 biosynthesis in Pseudomonas denitrificans. J. Bacteriol. 174 (1992) 7445-7451. [PMID: 1429466]
2. Warren, M.J., Raux, E., Schubert, H.L. and Escalante-Semerena, J.C. The biosynthesis of adenosylcobalamin (vitamin B12). Nat. Prod. Rep. 19 (2002) 390-412. [PMID: 12195810]