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. 2008 Feb;190(3):1027-35.
doi: 10.1128/JB.01483-07. Epub 2007 Nov 16.

PhyR is involved in the general stress response of Methylobacterium extorquens AM1

Benjamin Gourion  1 , Anne Francez-Charlot, Julia A Vorholt
Affiliations

PhyR is involved in the general stress response of Methylobacterium extorquens AM1

Benjamin Gourion et al. J Bacteriol. 2008 Feb.

Abstract

PhyR represents a novel alphaproteobacterial family of response regulators having a structure consisting of two domains; a predicted amino-terminal extracytoplasmic function (ECF) sigma factor-like domain and a carboxy-terminal receiver domain. PhyR was first described in Methylobacterium extorquens AM1, in which it has been shown to be essential for plant colonization, probably due to its suggested involvement in the regulation of a number of stress proteins. Here we investigated the PhyR regulon using microarray technology. We found that the PhyR regulon is rather large and that most of the 246 targets are under positive control. Mapping of transcriptional start sites revealed candidate promoters for PhyR-mediated regulation. One of these promoters, an ECF-type promoter, was identified upstream of one-third of the target genes by in silico analysis. Among the PhyR targets are genes predicted to be involved in multiple stress responses, including katE, osmC, htrA, dnaK, gloA, dps, and uvrA. The induction of these genes is consistent with our phenotypic analyses which revealed that PhyR is involved in resistance to heat shock and desiccation, as well as oxidative, UV, ethanol, and osmotic stresses, in M. extorquens AM1. The finding that PhyR is involved in the general stress response was further substantiated by the finding that carbon starvation induces protection against heat shock and that this protection is at least in part dependent on PhyR.

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Figures

FIG. 1.
FIG. 1.
(A) Organization of the M. extorquens AM1 phyR region. Genes are represented by large open arrows. Transcript start sites of phyR (RMQ08198), RMQ08196, and RMQ12794 were identified by RACE and are indicated by bent arrows. Putative signal peptides are represented by a zigzag symbol. Genes induced in the phyR-overexpressing strain are labeled with a plus sign at the 5 prime end. (B) Alignment of promoter regions. Conserved −35 and −10 elements are indicated by shading. Transcription start sites identified experimentally are in bold type and underlined. Distances to the start codon are indicated.
FIG. 2.
FIG. 2.
Hydrogen peroxide, methylglyoxal, and formaldehyde resistance of the M. extorquens wild-type AM1, ΔphyR, and complemented ΔphyR/pBG11 strains as determined by disk diffusion assays. Exponential-phase cells were mixed with MM soft agar and overlaid onto MM agar plates. Disks (diameter, 5 mm) were placed on each plate, 5 μl of 10 M H2O2 (A), 40% methylglyoxal (B), or 12 M formaldehyde (C) was added to each disk, and the plates were incubated at 28°C for 3 days. The data indicate the diameters of the inhibition halos and are the means for three plates for each strain from three independent experiments; the error bars indicate the standard errors of the means. WT, wild type.
FIG. 3.
FIG. 3.
Thermal resistance of the M. extorquens wild-type AM1, ΔphyR derivative, and complemented ΔphyR/pBG11 strains. Cultures were grown at 28°C in MM containing methanol and succinate to an OD600 of 1. They were then directly challenged at 55°C or subjected to overnight carbon starvation before heat shock. Viability was determined by plating on solid minimal medium. WT, wild type.
FIG. 4.
FIG. 4.
UV light tolerance of the M. extorquens wild-type AM1, ΔphyR, and complemented ΔphyR pBG11/strains. Cell viability was tested by spotting dilution series of cells in exponential growth phase and exposing them to UV light (254 nm) for 30 s. WT, wild type.
FIG. 5.
FIG. 5.
Salt and ethanol tolerance of the M. extorquens wild-type AM1, ΔphyR, and complemented ΔphyR/pBG11 strains. Dilution series of cells in exponential growth phase were plated on MM (control) (A) or MM containing 100 mM NaCl (B) or 2% ethanol (C). WT, wild type.
FIG. 6.
FIG. 6.
Desiccation test with the M. extorquens wild-type AM1, ΔphyR, and complemented ΔphyR/pBG11 strains. Cell viability was tested by spotting dilution series of cells in exponential growth phase on filter paper. Filters were laid on solid minimal medium immediately after a short drying period (control) (A) or after 3 days under a sterile airflow (B). WT, wild type.
FIG. 7.
FIG. 7.
Genetic organization of the phyR locus in different Alphaproteobacteria. The gene tags and scale are based on data deposited in the Uniref public database, with the exception of the two CDS located upstream of BMEI0372 and SMc0794, which show 38 and 31% amino acid identity with RMQ12793, respectively, and are not annotated as genes in the Uniref database.
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References

    1. Akbar, S., S. Y. Lee, S. A. Boylan, and C. W. Price. 1999. Two genes from Bacillus subtilis under the sole control of the general stress transcription factor σB. Microbiology 1451069-1078. - PubMed
    1. Booth, I. R., M. D. Edwards, S. Black, U. Schumann, and S. Miller. 2007. Mechanosensitive channels in bacteria: signs of closure? Nat. Rev. Microbiol. 5431-440. - PubMed
    1. Booth, I. R., G. P. Ferguson, S. Miller, C. Li, B. Gunasekera, and S. Kinghorn. 2003. Bacterial production of methylglyoxal: a survival strategy or death by misadventure? Biochem. Soc. Trans. 311406-1408. - PubMed
    1. Boylan, S. A., A. R. Redfield, M. S. Brody, and C. W. Price. 1993. Stress-induced activation of the sigma B transcription factor of Bacillus subtilis. J. Bacteriol. 1757931-7937. - PMC - PubMed
    1. Chistoserdova, L., S.-W. Chen, A. Lapidus, and M. E. Lidstrom. 2003. Methylotrophy in Methylobacterium extorquens AM1 from a genomic point of view. J. Bacteriol. 1852980-2987. - PMC - PubMed

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