Fig. 2
Cobamide biosynthesis and structure. a The cobamide biosynthesis pathway is shown with each enzymatic step indicated by a white box labeled with the gene names and functional annotation. Subsections of the pathway and salvaging and remodeling pathways are bracketed or boxed with labels in bold. Orthologous enzymes that carry out similar reactions in aerobic and anaerobic corrin ring biosynthesis are indicated by dashed lines. b Structure of cobalamin. The upper ligand R can be a 5'-deoxyadenosyl or methyl group. Classes of possible lower ligand structures are also shown. Benzimidazoles: R1, R2 = H, OH, CH3, OCH3. Purines: R1 = H, CH3, NH2; R2 = H, NH2, OH, O. Phenolics: R = H, CH3.
