FIG. 1.

Coenzyme B₁₂ biosynthesis in serovar Typhimurium. Shown are the intermediates, substrates, and enzymes of the pathway. α-DAD, alpha-5,6-dimethylbenzimidazole adenine dinucleotide; Nm, nicotinamide; α-RP, alpharibazole-5′-phosphate; AdoCbl-P, adenosylcobalamin phosphate; CobA, ATP:Co(I)rrinoid adenosyltransferase; CbiB, putative AdoCbi-P synthetase; CobD, l-Thr O-3-phosphate decarboxylase; CobT, NaMN:5,6-dimethylbenzimidazole phosphoribosyltransferase; CobU, AdoCbi kinase and guanylyltransferase; CobS, cobalamin phosphate synthase; CobC, cobalamin-phosphate phosphatase; YcfN, thiamine kinase (AdoCbi kinase); CobY, nucleotidyltransferase from M. mazei. The box represents the corrinoid transport system (BtuBFCD). AdoCbyP (in brackets) is a proposed intermediate.