Conservation of thiol-oxidative stress responses regulated by SigR orthologues in actinomycetes.
Mol Microbiol, 2012/7;85(2):326-44.
Kim MS[1], Dufour YS, Yoo JS, Cho YB, Park JH, Nam GB, Kim HM, Lee KL, Donohue TJ, Roe JH
Affiliations
PMID: 22651816DOI: 10.1111/j.1365-2958.2012.08115.x
Impact factor: 3.979
Abstract
Numerous thiol-reactive compounds cause oxidative stress where cells counteract by activation of survival strategies regulated by thiol-based sensors. In Streptomyces coelicolor, a model actinomycete, a sigma/antisigma pair SigR/RsrA controls the response to thiol-oxidative stress. To unravel its full physiological functions, chromatin immuno-precipitation combined with sequence and transcript analyses were employed to identify 108 SigR target genes in S. coelicolor and to predict orthologous regulons across actinomycetes. In addition to reported genes for thiol homeostasis, protein degradation and ribosome modulation, 64 additional operons were identified suggesting new functions of this global regulator. We demonstrate that SigR maintains the level and activity of the housekeeping sigma factor HrdB during thiol-oxidative stress, a novel strategy for stress responses. We also found that SigR defends cells against UV and thiol-reactive damages, in which repair UvrA takes a part. Using a refined SigR-binding sequence model, SigR orthologues and their targets were predicted in 42 actinomycetes. This revealed a conserved core set of SigR targets to function for thiol homeostasis, protein quality control, possible modulation of transcription and translation, flavin-mediated redox reactions, and Fe-S delivery. The composition of the SigR regulon reveals a robust conserved physiological mechanism to deal with thiol-oxidative stress from bacteria to human.
MeSH terms
Binding Sites; Chromatin Immunoprecipitation; Cluster Analysis; Gene Expression Profiling; Microbial Viability; Oxidative Stress; Regulon; Sequence Analysis, DNA; Sequence Homology, Nucleic Acid; Streptomyces coelicolor; Stress, Physiological; Sulfhydryl Compounds; Transcription Factors
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