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Please use this identifier to cite or link to this item: http://hdl.handle.net/1942/17743

Title: Canonical and non-canonical EcfG sigma factors control the general stress response in Rhizobium etli
Authors: Jans, Ann
Vercruysse, Maarten
Gao, Shanjun
Engelen, Kristof
Fauvart, Maarten
Michiels, Jan
Issue Date: 2013
Citation: MICROBIOLOGYOPEN, 2 (6), p. 976-987
Abstract: A core component of the α-proteobacterial general stress response (GSR) is the extracytoplasmic function (ECF) sigma factor EcfG, exclusively present in this taxonomic class. Half of the completed α-proteobacterial genome sequences contain two or more copies of genes encoding σEcfG-like sigma factors, with the primary copy typically located adjacent to genes coding for a cognate anti-sigma factor (NepR) and two-component response regulator (PhyR). So far, the widespread occurrence of additional, non-canonical σEcfG copies has not satisfactorily been explained. This study explores the hierarchical relation between Rhizobium etli σEcfG1 and σEcfG2, canonical and non-canonical σEcfG proteins, respectively. Contrary to reports in other species, we find that σEcfG1 and σEcfG2 act in parallel, as nodes of a complex regulatory network, rather than in series, as elements of a linear regulatory cascade. We demonstrate that both sigma factors control unique yet also shared target genes, corroborating phenotypic evidence. σEcfG1 drives expression of rpoH2, explaining the increased heat sensitivity of an ecfG1 mutant, while katG is under control of σEcfG2, accounting for reduced oxidative stress resistance of an ecfG2 mutant. We also identify non-coding RNA genes as novel σEcfG targets. We propose a modified model for GSR regulation in R. etli, in which σEcfG1 and σEcfG2 function largely independently. Based on a phylogenetic analysis and considering the prevalence of α-proteobacterial genomes with multiple σEcfG copies, this model may also be applicable to numerous other species.
Notes: Reprint Address: Michiels, J (reprint author) Ctr Microbial & Plant Genet, Kasteelpk Arenberg 20,Box 2460, B-3001 Heverlee, Belgium. Addresses: Show the Organization-Enhanced name(s) [ 1 ] Katholieke Univ Leuven, Ctr Microbial & Plant Genet, B-3001 Heverlee, Belgium Show the Organization-Enhanced name(s) [ 2 ] Hasselt Univ, Biomed Res Inst, B-3590 Diepenbeek, Belgium Show the Organization-Enhanced name(s) [ 3 ] Fdn Edmund Mach, Res & Innovat Ctr, Dept Computat Biol, I-38010 Trento, TN, Italy E-mail Addresses:jan.michiels@biw.kuleuven.be
URI: http://hdl.handle.net/1942/17743
DOI: 10.1002/mbo3.137
ISI #: 000342351900008
ISSN: 2045-8827
Category: A1
Type: Journal Contribution
Validation: ecoom, 2015
Appears in Collections: Research publications

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