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Control of dimethylsulfoxide reductase expression in Rhodobacter capsulatus: the role of carbon metabolites and the response regulators DorR and RegA

Kappler, Ulrike, Huston, Wilhelmina M., & McEwan, Alastair G. (2002) Control of dimethylsulfoxide reductase expression in Rhodobacter capsulatus: the role of carbon metabolites and the response regulators DorR and RegA. Microbiology, 148(2), pp. 605-614.

Abstract

Regulation of the expression of dimethylsulfoxide (DMSO) reductase was investigated in the purple phototrophic bacterium Rhodobacter capsulatus. Under phototrophic, anaerobic conditions with malate as carbon source, DMSO caused an approximately 150-fold induction of DMSO reductase activity. The response regulator DorR was required for DMSO-dependent induction and also appeared to slightly repress DMSO reductase expression in the absence of substrate. Likewise, when pyruvate replaced malate as carbon source there was an induction of DMSO reductase activity in cells grown at low light intensity (16 W m(-2)) and again this induction was dependent on DorR. The level of DMSO reductase activity in aerobically grown cells was elevated when pyruvate replaced malate as carbon source. One possible explanation for this is that acetyl phosphate, produced from pyruvate, may activate expression of DMSO reductase by direct phosphorylation of DorR, leading to low levels of induction of dor gene expression in the absence of DMSO. A mutant lacking the global response regulator of photosynthesis gene expression, RegA, exhibited high levels of DMSO reductase in the absence of DMSO, when grown phototrophically with malate as carbon source. This suggests that phosphorylated RegA acts as a repressor of dor operon expression under these conditions. It has been proposed elsewhere that RegA-dependent expression is negatively regulated by the cytochrome cbb3 oxidase. A cco mutant lacking cytochrome cbb3 exhibited significantly higher levels of phi[dorA::lacZ] activity in the presence of DMSO compared to wild-type cells and this is consistent with the above model. Pyruvate restored DMSO reductase expression in the regA mutant to the same pattern as found in wild-type cells. These data suggest that R. capsulatus contains a regulator of DMSO respiration that is distinct from DorR and RegA, is activated in the presence of pyruvate, and acts as a negative regulator of DMSO reductase expression.

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ID Code: 7174
Item Type: Journal Article
Additional Information: For more information, please refer to the journal's website (see hypertext link) or contact the author: w.huston@qut.edu.au
Additional URLs:
Keywords: respiratory chain, Rhodobacter capsulatus, metabolism, regulation
ISSN: 1350-0872
Subjects: Australian and New Zealand Standard Research Classification > BIOLOGICAL SCIENCES (060000) > MICROBIOLOGY (060500) > Microbial Genetics (060503)
Australian and New Zealand Standard Research Classification > BIOLOGICAL SCIENCES (060000) > MICROBIOLOGY (060500) > Infectious Agents (060502)
Australian and New Zealand Standard Research Classification > BIOLOGICAL SCIENCES (060000) > MICROBIOLOGY (060500) > Bacteriology (060501)
Divisions: Past > QUT Faculties & Divisions > Faculty of Science and Technology
Past > Institutes > Institute for Creative Industries and Innovation
Copyright Owner: Copyright 2002 Society for General Microbiology
Deposited On: 27 Apr 2007
Last Modified: 22 Apr 2010 01:58

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