Molecular anatomy of 2-oxoacid : ferredoxin oxidoreductase from hyperthermophilic archaea

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2-Oxoacid : ferredoxin oxidoreductase (OFOR) catalyzes oxidative decarboxylation of 2-oxoacids, using ferredoxin as an electron acceptor. The OFOR is found among all archaea, certain eubacteria, and certain eukaryotes. The structure-function relationship of OFOR is not clearly elucidated. This is partly because of the difficulty in constructing gene expression system that produces stable enzyme, or of the intrinsic oxygen-sensitivity of most OFORS from anaerobic organisms. In the present study, we first constructed the OFOR gene expression system from Sulfolobus sp. strain 7, compared the characteristics of recombinant enzyme with natural one. The two OFORs were indistinguishable by the criteria so far investigated. Based on the gene expression system, a series of mutants that is implicated as catalytic sites were designed. Some of them lost activity, and the other were found to change its substrate specificity.