This family of proteins represent the nicotinate-nucleotide- dimethylbenzimidazole phosphoribosyltransferase (NN:DBI PRT) enzymes involved in dimethylbenzimidazole synthesis. This function is essential to de novo cobalamin (vitamin B12) production in bacteria. Nicotinate mononucleotide (NaMN):5,6-dimethylbenzimidazole (DMB) phosphoribosyltransferase (CobT) from Salmonella enterica plays a central role in the synthesis of alpha-ribazole-5'-phosphate, an intermediate for the lower ligand of cobalamin [2].

1: 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

2: Capture of a labile substrate by expulsion of water molecules from the active site of nicotinate mononucleotide:5,6-dimethylbenzimidazole phosphoribosyltransferase (CobT) from Salmonella enterica. Cheong CG, Escalante-Semerena JC, Rayment I; J Biol Chem 2002;277:41120-41127. PMID:12101181