Genetic and biochemical characterization of a short-chain alcohol dehydrogenase from the hyperthermophilic archaeon Pyrococcus furiosus

The gene encoding a short-chain alcohol dehydrogenase, AdhA, has been ident ified in the hyperthermophilic archaeon Pyrococcus furiosus, as part of an operon that encodes two glycosyl hydrolases, the beta -glucosidase CelB and the endoglucanase LamA. The adhA gene was functionally expressed in Escher ichia coli, and AdhA was subsequently purified to homogeneity. The quaterna ry structure of AdhA is a dimer of identical 26-kDa subunits. AdhA is an NA DPH-dependent oxidoreductase that converts alcohols to the corresponding al dehydes/ketones and vice versa, with a rather broad substrate specificity. Maximal specific activities were observed with 2-pentanol (46 U.mg(-1)) and pyruvaldehyde (32 U.mg(-1)) in the oxidative and reductive reaction, respe ctively. AdhA has an optimal activity at 90 degreesC, at which temperature it has a half life of 22.5 h. The expression of the adhA gene in P. furiosu s was demonstrated by activity measurements and immunoblot analysis of cell extracts. A role of this novel type of archaeal alcohol dehydrogenase in c arbohydrate fermentation is discussed.