FAD binding,cobinamide binding and active site communication in the corrin reductase (CobR) |
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| Authors: | Andrew?D Lawrence Samantha?L Taylor Alan Scott Michelle?L Rowe Christopher?M Johnson Stephen?E J Rigby Michael?A Geeves Richard?W Pickersgill Mark?J Howard Martin?J Warren |
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| Institution: | *School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, U.K.;†Medical Research Council Laboratory for Molecular Biology, Hills Road, Cambridge CB2 0QH, U.K.;‡Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.;§School of Biological and Chemical Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, U.K. |
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| Abstract: | Adenosylcobalamin, the coenzyme form of vitamin B12, is one Nature''s most complex coenzyme whose de novo biogenesis proceeds along either an anaerobic or aerobic metabolic pathway. The aerobic synthesis involves reduction of the centrally chelated cobalt metal ion of the corrin ring from Co(II) to Co(I) before adenosylation can take place. A corrin reductase (CobR) enzyme has been identified as the likely agent to catalyse this reduction of the metal ion. Herein, we reveal how Brucella melitensis CobR binds its coenzyme FAD (flavin dinucleotide) and we also show that the enzyme can bind a corrin substrate consistent with its role in reduction of the cobalt of the corrin ring. Stopped-flow kinetics and EPR reveal a mechanistic asymmetry in CobR dimer that provides a potential link between the two electron reduction by NADH to the single electron reduction of Co(II) to Co(I). |
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| Keywords: | enzyme kinetics enzyme structure NMR vitamins and cofactors X-ray crystallography |
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