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Pure Appl. Chem., 2007, Vol. 79, No. 12, pp. 2179-2188

http://dx.doi.org/10.1351/pac200779122179

Recent discoveries in the pathways to cobalamin (coenzyme B12) achieved through chemistry and biology*

A. Ian Scott and Charles A. Roessner

Center for Biological NMR, Department of Chemistry, Texas A and M University, College Station, TX 77843-3255, USA

Abstract: The genetic engineering of Escherichia coli for the over-expression of enzymes of the aerobic and anaerobic pathways to cobalamin has resulted in the in vivo and in vitro biosynthesis of new intermediates and other products that were isolated and characterized using a combination of bioorganic chemistry and high-resolution NMR. Analyses of these products were used to deduct the functions of the enzymes that catalyze their synthesis. CobZ, another enzyme for the synthesis of precorrin-3B of the aerobic pathway, has recently been described, as has been BluB, the enzyme responsible for the oxygen-dependent biosynthesis of dimethylbenzimidazole. In the anaerobic pathway, functions have recently been experimentally confirmed for or assigned to the CbiMNOQ cobalt transport complex, CbiA (a,c side chain amidation), CbiD (C-1 methylation), CbiF (C-11 methylation), CbiG (lactone opening, deacylation), CbiP (b,d,e,g side chain amidation), and CbiT (C-15 methylation, C-12 side chain decarboxylation). The dephosphorylation of adenosylcobalamin-phosphate, catalyzed by CobC, has been proposed as the final step in the biosynthesis of adenosylcobalamin.
*Invited contribution to a collection of papers for the IUPAC project 2005-042-1-300 "Chemistry for Biology". Other contributions to the project are published in this issue, pp. 2179-2366.