The aerobic cobalt chelatase (aerobic cobalamin biosynthesis pathway) consists of three subunits, CobT, CobN (IPR003672) and CobS (IPR006537).
Cobalamin (vitamin B12) can be complexed with metal via the ATP-dependent reactions (aerobic pathway) (e.g., in Pseudomonas denitrificans) or via ATP-independent reactions (anaerobic pathway) (e.g., in Salmonella typhimurium). The corresponding cobalt chelatases are not homologous. However, aerobic cobalt chelatase subunits CobN and CobS are homologous to Mg-chelatase subunits BchH and BchI, respectively. CobT, too, has been found to be remotely related to the third subunit of Mg-chelatase, BchD (involved in bacteriochlorophyll synthesis, e.g., in Rhodobacter capsulatus).
This enzyme belongs to the family of ligases, specifically those forming nitrogen-D-metal bonds in coordination complexes. The systematic name of this enzyme class is hydrogenobyrinic-acid-a,c-diamide:cobalt cobalt-ligase (ADP-forming). Other names in common use include hydrogenobyrinic acid a,c-diamide cobaltochelatase, CobNST, and CobNCobST. This enzyme participates in porphyrin and chlorophyll metabolism.
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^Crouzet J, Cameron B, Blanche F, Thibaut D, Debussche L, Couder M (1992). "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 (22): 7445–7451. PMC207441. PMID1429466.
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Debussche L, Couder M, Thibaut D, Cameron B, Crouzet J, Blanche F (1992). "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 (22): 7445–51. PMC207441. PMID1429466.
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