Affiliation:
1. Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
2. Institute of Environmental Genomics and Department of Botany and Microbiology, University of Oklahoma, Norman, Oklahoma
Abstract
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.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
75 articles.
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