Protein Domain : Cobaltochelatase subunit CobS IPR006537

Type	Family
Description	These sequences are related to the Pseudomonas denitrificans CobS gene product, which is a cobalt chelatase subunit of MW ~37kDa [ ] that functions in cobalamin biosynthesis. Cobalamin (vitamin B12) can be synthesized via several pathways, including an aerobic pathway (found in P. denitrificans) and an anaerobic pathway (found in Salmonella typhimurium). These pathways differ in the point of cobalt insertion during corrin ring formation []. There are apparently a number of variations on these two pathways, where the major differences seem to be concerned with the process of ring contraction []. Confusion regarding the functions of enzymes found in the aerobic vs. anaerobic pathways has arisen because nonhomologous genes in these different pathways were given the same gene symbols. Thus, cobS in the aerobic pathway (P. denitrificans) is not a homologue of cobS in the anaerobic pathway (S. typhimurium). It should be noted that Escherichia coli synthesizes cobalamin only when it is supplied with the precursor cobinamide, which is a complex intermediate. Additionally, all E. coli cobalamin synthesis genes (cobU, cobS and cobT) were named after their S. typhimurium homologues which function in the anaerobic cobalamin synthesis pathway []. The aerobic pathway cobalt chelatase is a heterotrimeric, ATP-dependent enzyme that catalyzes cobalt insertion during cobalamin biosynthesis. The other two subunits are the P. denitrificans CobT () and CobN ( CobN/magnesium chelatase) proteins.
Short Name	PD_CobS