Role of the Regulatory GenerirAin the Transcriptional Response ofSinorhizobium melilotito Iron Limitation

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Bibliographische Detailangaben
Zeitschriftentitel:	Applied and Environmental Microbiology
Personen und Körperschaften:	Chao, Tzu-Chiao, Buhrmester, Jens, Hansmeier, Nicole, Pühler, Alfred, Weidner, Stefan
In:	Applied and Environmental Microbiology, 71, 2005, 10, S. 5969-5982
Format:	E-Article
Sprache:	Englisch
veröffentlicht:	American Society for Microbiology
Schlagwörter:	Ecology Applied Microbiology and Biotechnology Food Science Biotechnology

Details
Zusammenfassung:	<jats:title>ABSTRACT</jats:title><jats:p>A regulatory network of<jats:italic>Sinorhizobium meliloti</jats:italic>genes involved in adaptation to iron-limiting conditions and the involvement of the rhizobial iron regulator gene (<jats:italic>rirA</jats:italic>) were analyzed by mutation and microarray analyses. A constructed<jats:italic>S. meliloti rirA</jats:italic>mutant exhibited growth defects and enhanced H<jats:sub>2</jats:sub>O<jats:sub>2</jats:sub>sensitivity in the presence of iron, but symbiotic nitrogen fixation was not affected. To identify iron-responsive and RirA-regulated<jats:italic>S. meliloti</jats:italic>genes, a transcriptome approach using whole-genome microarrays was used. Altogether, 45 genes were found to be jointly derepressed by mutation of<jats:italic>rirA</jats:italic>and under different iron-limited conditions. As expected, a number of genes involved in iron transport (e.g.,<jats:italic>hmuPSTU</jats:italic>,<jats:italic>shmR</jats:italic>,<jats:italic>rhbABCDEF</jats:italic>,<jats:italic>rhtX</jats:italic>, and<jats:italic>rhtA</jats:italic>) and also genes with predicted functions in energy metabolism (e.g.,<jats:italic>fixN3</jats:italic>,<jats:italic>fixP3</jats:italic>, and<jats:italic>qxtAB</jats:italic>) and exopolysaccharide production (e.g.,<jats:italic>exoY</jats:italic>and<jats:italic>exoN</jats:italic>) were found in this group of genes. In addition, the iron deficiency response of<jats:italic>S. meliloti</jats:italic>also involved<jats:italic>rirA</jats:italic>-independent expression changes, including repression of the<jats:italic>S. meliloti</jats:italic>flagellar regulon. Finally, the RirA modulon also includes genes that are not iron responsive, including a gene cluster putatively involved in Fe-S cluster formation (<jats:italic>sufA</jats:italic>,<jats:italic>sufS</jats:italic>,<jats:italic>sufD</jats:italic>,<jats:italic>sufC</jats:italic>, and<jats:italic>sufB</jats:italic>).</jats:p>
Umfang:	5969-5982
ISSN:	0099-2240 1098-5336
DOI:	10.1128/aem.71.10.5969-5982.2005