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Sulfate_Pyruvate_Desulfovibrio_G20

ABSTRACT: In order to genetically determine the essential components of electron flow during respiration of sulfate by the anaerobe Desulfovibrio desulfuricans G20, a growth mode independent of sulfate is needed. However, a mutant of the G20 strain, I2, lacking the abundant type-1 tetraheme cytochrome c3 (TpI-c3), was found to be altered in growth with sulfate. Here we report that I2 does not reduce sulfate with electrons from pyruvate. In contrast, in the absence of sulfate, fermentative growth of I2 on pyruvate actually yielded slightly greater cellular protein than G20. When provided lactate with sulfate or when fermenting pyruvate, I2 produced more hydrogen and accumulated little if any succinate. G20 grows by fumarate dismutation and accumulates the theoretical 2:1 ratio of the end products, succinate and acetate, respectively. In contrast, I2 did not grow on fumarate alone. We inferred that TpI-c3 might be required for transfer of electrons to the membrane-bound fumarate reductase or for establishing a redox environment needed to trigger synthesis of the enzymes for succinate production. Microarray and proteomic analyses of gene and protein expression in I2 compared with G20 were consistent with increases in those enzymes predicted to be necessary for the generation of end products measured. These results support a role for the periplasmic TpI-c3 in electron flow from pyruvate to sulfate and in establishing conditions for enzyme production for fumarate dismutation. In addition, evidence for the simultaneous operation of respiratory electron flow and substrate-level phosphorylation was obtained from end product analysis.

ORGANISM(S): Oleidesulfovibrio alaskensis G20

PROVIDER: GSE21287 | GEO | 2010/04/25

SECONDARY ACCESSION(S): PRJNA126593

REPOSITORIES: GEO

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Project description:In order to obtain a global view of energy metabolism pathways of the sulfate-reducer Desulfovibrio vulgaris Hildenborough and the proteins involved therein whole-genome microarrays were used to compare the transcriptional response of cells grown with hydrogen/sulfate, pyruvate/sulfate, lactate/thiosulfate, and pyruvate with limiting sulfate, relative to growth in standard lactate/sulfate condition. Growth with hydrogen/sulfate showed the largest number of differently expressed genes and the largest changes in expression levels. The most up-regulated energy metabolism genes were those coding for the periplasmic [NiFeSe] hydrogenase, followed by the Ech hydrogenase, and the most down-regulated were genes coding for the Coo hydrogenase. The results point to the involvement of formate cycling and the ethanol pathway during growth on hydrogen, whereas there is evidence for CO cycling during growth on lactate and pyruvate, but not on H2. Growth with thiosulfate showed the hallmarks of a reduced energy status of the cells with down regulation of the ATP synthase and the Qmo and Dsr complexes., whereas growth with pyruvate showed the smallest differences but an increased role for the Ech hydrogenase.that in this case functions in reverse from the case of growth with H2. The multiple periplasmic hydrogenases and formate dehydrogenases, do not display the same regulation pattern showing that their metabolic roles are not totally interchangeable. This result together with the observation that several genes coding for proteins that have not been biochemically characterised were considerably affected in this study, reveals a more complex energy metabolism than previously considered and provides guidance for further studies. Keywords: Growth protocol Desulfovibrio vulgaris Hildenborough was cultured at 37°C with pyruvate as the only electron donor (with sulfate as the electron acceptor) to mid-log phase. Cultures were also cultivated similarly using lactate as the sole electron donor to mid-log phase. Gene expression profiles of cultures grown with pyruvate as the electron donor were compared with those of the cultures grown with lactate as the electron donor for sulfate reduction. Total RNA was harvested from three replicate cultures for microarray analysis. RNA extraction, purification, and labeling were performed independently on each cell sample.Two samples of each total RNA preparation were labeled, one with Cy3-dUTP and another with Cy5-dUTP for microarray hybridization (dye swap).

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Sulfate_Pyruvate_Desulfovibrio_G20

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