title: Identification of an uptake hydrogenase for hydrogen-dependent dissimilatory azoreduction by Shewanella decolorationis S12.
abstract: Shewanella decolorationis S12, a representative dissimilatory azo-reducing bacterium of Shewanella genus, can grow by coupling the oxidation of hydrogen to the reduction of azo compounds as the sole electron acceptor, indicating that an uptake hydrogenase is an important component for electron transfer for azoreduction. For searching to the uptake hydrogenase in the genome of S. decolorationis, two operons, hyd and hya, were cloned and sequenced, which encode periplasmically oriented Fe-only hydrogenase and a Ni-Fe hydrogenase, respectively, according to the homologous comparison with other bacterial hydrogenases. In order to assess the roles of these two enzymes in hydrogen-dependent azoreduction and growth, hyd- and hya-deficient mutants were generated by gene replacement. Hya was found to be required for hydrogen-dependent reduction of azo compound by resting cell suspensions and to be essential for growth with hydrogen as electron donor and azo compound as electron acceptor. Hyd, in contrast, was not. These findings suggest that Hya is an essential respiratory hydrogenase of dissimilatory azoreduction in S. decolorationis.
authors.affiliation: Key Laboratory of Tropical Marine Environment Dynamics (LED), South China Sea Institute of Oceanography, Chinese Academy of Sciences, Guangzhou, People's Republic of China.
authors.forename: Yi-Guo
authors.initials: YG
authors.lastname: Hong
authors.forename: Jun
authors.initials: J
authors.lastname: Guo
authors.forename: Guo-Ping
authors.initials: GP
authors.lastname: Sun
mesh_terms: D001391:Azo Compounds / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D006859:Hydrogen / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D009876:Operon; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D020592:Shewanella / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism
chemical_list: D001391:Azo Compounds; D001426:Bacterial Proteins; D006859:Hydrogen; D010088:Oxidoreductases; C029746:uptake hydrogenase