title: Function of periplasmic hydrogenases in the sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough.
abstract: The sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough possesses four periplasmic hydrogenases to facilitate the oxidation of molecular hydrogen. These include an [Fe] hydrogenase, an [NiFeSe] hydrogenase, and two [NiFe] hydrogenases encoded by the hyd, hys, hyn1, and hyn2 genes, respectively. In order to understand their cellular functions, we have compared the growth rates of existing (hyd and hyn1) and newly constructed (hys and hyn-1 hyd) mutants to those of the wild type in defined media in which lactate or hydrogen at either 5 or 50% (vol/vol) was used as the sole electron donor for sulfate reduction. Only strains missing the [Fe] hydrogenase were significantly affected during growth with lactate or with 50% (vol/vol) hydrogen as the sole electron donor. When the cells were grown at low (5% [vol/vol]) hydrogen concentrations, those missing the [NiFeSe] hydrogenase suffered the greatest impairment. The growth rate data correlated strongly with gene expression results obtained from microarray hybridizations and real-time PCR using mRNA extracted from cells grown under the three conditions. Expression of the hys genes followed the order 5% hydrogen>50% hydrogen>lactate, whereas expression of the hyd genes followed the reverse order. These results suggest that growth with lactate and 50% hydrogen is associated with high intracellular hydrogen concentrations, which are best captured by the higher activity, lower affinity [Fe] hydrogenase. In contrast, growth with 5% hydrogen is associated with a low intracellular hydrogen concentration, requiring the lower activity, higher affinity [NiFeSe] hydrogenase.
authors.affiliation: Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada.
authors.forename: Sean M
authors.initials: SM
authors.lastname: Caffrey
authors.forename: Hyung-Soo
authors.initials: HS
authors.lastname: Park
authors.forename: Johanna K
authors.initials: JK
authors.lastname: Voordouw
authors.forename: Zhili
authors.initials: Z
authors.lastname: He
authors.forename: Jizhong
authors.initials: J
authors.lastname: Zhou
authors.forename: Gerrit
authors.initials: G
authors.lastname: Voordouw
mesh_terms: D003470:Culture Media / Q000737:chemistry; D016969:Desulfovibrio vulgaris / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D017353:Gene Deletion; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D006859:Hydrogen / Q000378:metabolism; D006864:Hydrogenase / Q000235:genetics / Q000502:physiology*; D019344:Lactic Acid / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D010084:Oxidation-Reduction; D033903:Periplasmic Proteins / Q000235:genetics / Q000502:physiology*; D013431:Sulfates / Q000378:metabolism*
chemical_list: D003470:Culture Media; D033903:Periplasmic Proteins; D013431:Sulfates; D019344:Lactic Acid; D006859:Hydrogen; D006864:Hydrogenase