This family consists of various cobyrinic acid a,c-diamide synthases. These include CbiA Swiss:P29946 and CbiP Swiss:Q05597 from S.typhimurium [4], and CobQ Swiss:Q52686 from R. capsulatus [3]. These amidases catalyse amidations to various side chains of hydrogenobyrinic acid or cobyrinic acid a,c-diamide in the biosynthesis of cobalamin (vitamin B12) from uroporphyrinogen III. Vitamin B12 is an important cofactor and an essential nutrient for many plants and animals and is primarily produced by bacteria [4]. The family also contains dethiobiotin synthetases as well as the plasmid partitioning proteins of the MinD/ParA family [6].

1: Cobalamin (vitamin B12) biosynthesis: identification and characterization of a Bacillus megaterium cobI operon. Raux E, Lanois A, Warren MJ, Rambach A, Thermes C; Biochem J 1998;335:159-166. PMID:9742225

2: Cobalamin (vitamin B12) biosynthesis: functional characterization of the Bacillus megaterium cbi genes required to convert uroporphyrinogen III into cobyrinic acid a,c-diamide. Raux E, Lanois A, Rambach A, Warren MJ, Thermes C; Biochem J 1998;335:167-173. PMID:9742226

3: Identification and sequence analysis of genes involved in late steps in cobalamin (vitamin B12) synthesis in Rhodobacter capsulatus. Pollich M, Klug G; J Bacteriol 1995;177:4481-4487. PMID:7635831

4: Characterization of the cobalamin (vitamin B12) biosynthetic genes of Salmonella typhimurium. Roth JR, Lawrence JG, Rubenfield M, Kieffer-Higgins S, Church GM; J Bacteriol 1993;175:3303-3316. PMID:8501034

5: The synthetase domains of cobalamin biosynthesis amidotransferases cobB and cobQ belong to a new family of ATP-dependent amidoligases, related to dethiobiotin synthetase. Galperin MY, Grishin NV; Proteins 2000;41:238-247. PMID:10966576

6: A family of ATPases involved in active partitioning of diverse bacterial plasmids. Motallebi-Veshareh M, Rouch DA, Thomas CM; Mol Microbiol 1990;4:1455-1463. PMID:2149583