| Primary Identifier | IPR021744 | Type | Domain |
| Short Name | CbiG_N |
| description | Members of this family are involved in cobalamin synthesis. The gene encoded by has been designated cbiH but in fact represents a fusion between cbiH and cbiG. As other multi-functional proteins involved in cobalamin biosynthesis catalyse adjacent steps in the pathway, including CysG, CobL (CbiET), CobIJ and CobA-HemD, it is therefore possible that CbiG catalyses a reaction step adjacent to CbiH. In the anaerobic pathway such a step could be the formation of a gamma lactone, which is thought to help to mediate the anaerobic ring contraction process []. Within the cobalamin synthesis pathway CbiG catalyses the both the opening of the lactone ring and the extrusion of the two-carbon fragment of cobalt-precorrin-5A from C-20 and its associated methyl group (deacylation) to give cobalt-precorrin-5B. The N-terminal of the enzyme is conserved in this family, and the C-terminal and the mid-sections are conserved independently in other families, CbiG_C and CbiG_mid, although the distinct function of each region is unclear. |
