Figure 1

The aerobic and anaerobic pathways of cobalamin synthesis. CobL in the aerobic pathway is colored red. CbiE and CbiT, which are equivalent to CobL, are colored blue and red with a boxed label, respectively, in the anaerobic pathway. The chemical structures of cobalt-precorrin-6B, 7 and 8, which are the substrates and products of CbiE and CbiT, are shown at the bottom of the figure.