IUBMB Enzyme Nomenclature


Accepted name: sirohydrochlorin cobaltochelatase

Reaction: cobalt-sirohydrochlorin + 2 H+ = sirohydrochlorin + Co2+

For diagram of corrin and siroheme biosynthesis (part 2), click here

Other name(s): CbiK; CbiX; CbiXS; anaerobic cobalt chelatase; cobaltochelatase [ambiguous]; sirohydrochlorin cobalt-lyase

Systematic name: cobalt-sirohydrochlorin cobalt-lyase (sirohydrochlorin-forming)

Comments: This enzyme, which forms part of the anaerobic (early cobalt insertion) cobalamin biosynthesis pathway, is an ATP-independent type II chelatase. Two distinct forms are known - a primordial form named CbiX, which is most common in archaea, and a strictly bacterial form named CbiK. See EC, cobaltochelatase, for the cobaltochelatase that participates in the aerobic cobalamin biosynthesis pathway.

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB


1. Raux, E., Thermes, C., Heathcote, P., Rambach, A. and Warren, M.J. A role for Salmonella typhimurium cbiK in cobalamin (vitamin B12) and siroheme biosynthesis. J. Bacteriol. 179 (1997) 3202-3212. [PMID: 9150215]

2. Schubert, H.L., Raux, E., Wilson, K.S. and Warren, M.J. Common chelatase design in the branched tetrapyrrole pathways of heme and anaerobic cobalamin synthesis. Biochemistry 38 (1999) 10660-10669. [PMID: 10451360]

3. 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]

4. Brindley, A.A., Raux, E., Leech, H.K., Schubert, H.L. and Warren, M.J. A story of chelatase evolution: Identification and characterisation of a small 13-15 kDa 'ancestral' cobaltochelatase (CbiXS) in the Archaea. J. Biol. Chem. 278 (2003) 22388-22395. [PMID: 12686546]

5. Frank, S., Brindley, A.A., Deery, E., Heathcote, P., Lawrence, A.D., Leech, H.K., Pickersgill, R.W. and Warren, M.J. Anaerobic synthesis of vitamin B12: characterization of the early steps in the pathway. Biochem Soc Trans. 33 (2005) 811-814. [PMID: 16042604]

6. Lobo, S.A., Brindley, A.A., Romao, C.V., Leech, H.K., Warren, M.J. and Saraiva, L.M. Two distinct roles for two functional cobaltochelatases (CbiK) in Desulfovibrio vulgaris hildenborough. Biochemistry 47 (2008) 5851-5857. [PMID: 18457416]

7. Lobo, S.A., Videira, M.A., Pacheco, I., Wass, M.N., Warren, M.J., Teixeira, M., Matias, P.M., Romao, C.V. and Saraiva, L.M. Desulfovibrio vulgaris CbiK(P) cobaltochelatase: evolution of a haem binding protein orchestrated by the incorporation of two histidine residues. Environ. Microbiol. 19 (2017) 106-118. [PMID: 27486032]

[EC created 2004, modified 2020]

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