This Article Full Text (PDF) Other Versions of this Article: JB.01795-06v1 189/10/3784    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Zeller, T. Articles by Klug, G. Search for Related Content PubMed PubMed Citation Articles by Zeller, T. Articles by Klug, G.

 Previous Article  |  Next Article 

J. Bacteriol. doi:10.1128/JB.01795-06
Copyright (c) 2007, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.

Regulation of hydrogen peroxide-dependent gene expression in Rhodobacter sphaeroides: Regulatory functions of OxyR

Institut für Mikrobiologie und Molekularbiologie, University of Giessen, Giessen, Germany; Department of Molecular Biology, University of Wyoming, Laramie, Wyoming, USA

^* To whom correspondence should be addressed. Email: Gabriele.Klug{at}mikro.bio.uni-giessen.de.

	Abstract

Genome-wide transcriptome profiling was applied to reveal hydrogen peroxide (H₂O₂)-dependent regulatory mechanisms in the facultatively photosynthetic bacterium Rhodobacter sphaeroides. This study focuses on the role of the OxyR protein, a known regulator of the H₂O₂ response in bacteria. The transcriptome profiles of the R. sphaeroides wild type and the oxyR mutant strain exposed to 1 mM H₂O₂ for 7 min or without H₂O₂ exposure were analyzed. Three classes of OxyR-dependent genes were identified based on their expression pattern in wild type and mutant strains with differing predicted roles of oxidized or reduced OxyR as an activator of transcription. DNA binding studies revealed that OxyR binds upstream of class I genes, which are induced by H₂O₂ and show similar basal expression in the wild type and oxyR mutant strains. The effect of OxyR on class II genes that are also induced by H₂O₂ but show significantly lower basal levels in the wild type than in the mutant is indirect. Interestingly, reduced OxyR also activates expression of few genes (class III). The role of reduced OxyR as an activator is shown for the first time. Our data reveal that the OxyR mediated response is fast and transient. In addition, the involvement in the H₂O₂ response of additional regulatory pathways is uncovered.