scholarly journals Dual Control of Sinorhizobium meliloti RpoE2 Sigma Factor Activity by Two PhyR-Type Two-Component Response Regulators

2010 ◽  
Vol 192 (8) ◽  
pp. 2255-2265 ◽  
Author(s):  
Bénédicte Bastiat ◽  
Laurent Sauviac ◽  
Claude Bruand
Keyword(s):  
Sigma Factor ◽  
Sinorhizobium Meliloti ◽  
Regulatory System ◽  
Sigma Factors ◽  
Response Regulators ◽  
Methylobacterium Extorquens ◽  
General Stress Response ◽  
Ecf Sigma Factor ◽  
Proposed Model ◽  
Response To Stress

ABSTRACT RpoE2 is an extracytoplasmic function (ECF) sigma factor involved in the general stress response of Sinorhizobium meliloti, the nitrogen-fixing symbiont of the legume plant alfalfa. RpoE2 orthologues are widely found among alphaproteobacteria, where they play various roles in stress resistance and/or host colonization. In this paper, we report a genetic and biochemical investigation of the mechanisms of signal transduction leading to S. meliloti RpoE2 activation in response to stress. We showed that RpoE2 activity is negatively controlled by two paralogous anti-sigma factors, RsiA1 (SMc01505) and RsiA2 (SMc04884), and that RpoE2 activation by stress requires two redundant paralogous PhyR-type response regulators, RsiB1 (SMc01504) and RsiB2 (SMc00794). RsiB1 and RsiB2 do not act at the level of rpoE2 transcription but instead interact with the anti-sigma factors, and we therefore propose that they act as anti-anti-sigma factors to relieve RpoE2 inhibition in response to stress. This model closely resembles a recently proposed model of activation of RpoE2-like sigma factors in Methylobacterium extorquens and Bradyrhizobium japonicum, but the existence of two pairs of anti- and anti-anti-sigma factors in S. meliloti adds an unexpected level of complexity, which may allow the regulatory system to integrate multiple stimuli.

scholarly journals BldG and SCO3548 Interact Antagonistically To Control Key Developmental Processes in Streptomyces coelicolor

2009 ◽  
Vol 191 (8) ◽  
pp. 2541-2550 ◽  
Author(s):  
Archana Parashar ◽  
Kimberley R. Colvin ◽  
Dawn R. D. Bignell ◽  
Brenda K. Leskiw
Keyword(s):  
Sigma Factor ◽  
Antibiotic Production ◽  
Streptomyces Coelicolor ◽  
Affinity Purification ◽  
Regulatory System ◽  
Direct Interaction ◽  
Morphological Differentiation ◽  
Sigma Factors ◽  
Developmental Processes ◽  
Two Hybrid

ABSTRACT The similarity of BldG and the downstream coexpressed protein SCO3548 to anti-anti-sigma and anti-sigma factors, respectively, together with the phenotype of a bldG mutant, suggests that BldG and SCO3548 interact as part of a regulatory system to control both antibiotic production and morphological differentiation in Streptomyces coelicolor. A combination of bacterial two-hybrid, affinity purification, and far-Western analyses demonstrated that there was self-interaction of both BldG and SCO3548, as well as a direct interaction between the two proteins. Furthermore, a genetic complementation experiment demonstrated that SCO3548 antagonizes the function of BldG, similar to other anti-anti-sigma/anti-sigma factor pairs. It is therefore proposed that BldG and SCO3548 form a partner-switching pair that regulates the function of one or more sigma factors in S. coelicolor. The conservation of bldG and sco3548 in other streptomycetes demonstrates that this system is likely a key regulatory switch controlling developmental processes throughout the genus Streptomyces.

scholarly journals STAS Domain Only Proteins in Bacterial Gene Regulation

2021 ◽  
Vol 11 ◽  
Author(s):  
Brian E. Moy ◽  
J. Seshu
Keyword(s):  
Gene Expression ◽  
Sigma Factor ◽  
Environmental Changes ◽  
Vibrio Fischeri ◽  
Regulatory System ◽  
Sigma Factors ◽  
Amino Acid Sequences ◽  
Bacterial Gene ◽  
Anion Transporters ◽  
Stas Domain

Sulfate Transport Anti-Sigma antagonist domains (Pfam01740) are found in all branches of life, from eubacteria to mammals, as a conserved fold encoded by highly divergent amino acid sequences. These domains are present as part of larger SLC26/SulP anion transporters, where the STAS domain is associated with transmembrane anchoring of the larger multidomain protein. Here, we focus on STAS Domain only Proteins (SDoPs) in eubacteria, initially described as part of the Bacillus subtilisRegulation of Sigma B (RSB) regulatory system. Since their description in B. subtilis, SDoPs have been described to be involved in the regulation of sigma factors, through partner-switching mechanisms in various bacteria such as: Mycobacterium. tuberculosis, Listeria. monocytogenes, Vibrio. fischeri, Bordetella bronchiseptica, among others. In addition to playing a canonical role in partner-switching with an anti-sigma factor to affect the availability of a sigma factor, several eubacterial SDoPs show additional regulatory roles compared to the original RSB system of B. subtilis. This is of great interest as these proteins are highly conserved, and often involved in altering gene expression in response to changes in environmental conditions. For many of the bacteria we will examine in this review, the ability to sense environmental changes and alter gene expression accordingly is critical for survival and colonization of susceptible hosts.

scholarly journals The Single Extracytoplasmic-Function Sigma Factor of Xylella fastidiosa Is Involved in the Heat Shock Response and Presents an Unusual Regulatory Mechanism

2006 ◽  
Vol 189 (2) ◽  
pp. 551-560 ◽  
Author(s):  
José F. da Silva Neto ◽  
Tie Koide ◽  
Suely L. Gomes ◽  
Marilis V. Marques
Keyword(s):  
Heat Shock ◽  
Sigma Factor ◽  
Xylella Fastidiosa ◽  
Expression Profiles ◽  
Consensus Sequence ◽  
Gene Expression Profiles ◽  
Global Gene Expression ◽  
Sigma Factors ◽  
Bacterial Cells ◽  
Ecf Sigma Factor

ABSTRACT Genome sequence analysis of the bacterium Xylella fastidiosa revealed the presence of two genes, named rpoE and rseA, predicted to encode an extracytoplasmic function (ECF) sigma factor and an anti-sigma factor, respectively. In this work, an rpoE null mutant was constructed in the citrus strain J1a12 and shown to be sensitive to exposure to heat shock and ethanol. To identify the X. fastidiosa σE regulon, global gene expression profiles were obtained by DNA microarray analysis of bacterial cells under heat shock, identifying 21 σE-dependent genes. These genes encode proteins belonging to different functional categories, such as enzymes involved in protein folding and degradation, signal transduction, and DNA restriction modification and hypothetical proteins. Several putative σE-dependent promoters were mapped by primer extension, and alignment of the mapped promoters revealed a consensus sequence similar to those of ECF sigma factor promoters of other bacteria. Like other ECF sigma factors, rpoE and rseA were shown to comprise an operon in X. fastidiosa, together with a third open reading frame (XF2241). However, upon heat shock, rpoE expression was not induced, while rseA and XF2241 were highly induced at a newly identified σE-dependent promoter internal to the operon. Therefore, unlike many other ECF sigma factors, rpoE is not autoregulated but instead positively regulates the gene encoding its putative anti-sigma factor.

scholarly journals The ECF sigma factor PvdS regulates the type I-F CRISPR-Cas system in Pseudomonas aeruginosa

2020 ◽  
Author(s):  
Stephen Dela Ahator ◽  
Wang Jianhe ◽  
Lian-Hui Zhang
Keyword(s):  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Sigma Factor ◽  
Regulatory System ◽  
Stress Factors ◽  
Iron Limitation ◽  
Transport Systems ◽  
Type I ◽  
Ecf Sigma Factor ◽  
Wide Range

AbstractDuring infection, successful colonization of bacteria requires a fine-tuned supply of iron acquired via iron transport systems. However, the transport systems serve as phage attachment sites and entry portals for foreign nucleic acid. Most bacteria possess the CRISPR-Cas system, which targets and destroys foreign nucleic acids and prevents deleterious effects of horizontal gene transfer. To understand the regulation of the CRISPR-Cas system, we performed genome-wide random transposon mutagenesis which led to the identification of the Extracytoplasmic Function (ECF) Sigma factor, PvdS as a regulator of the Type I-F CRISPR-Cas system in P. aeruginosa. We show that under iron-depleted conditions PvdS induces the expression of the type I-F CRISPR-Cas system. This regulatory mechanism involves direct interaction of PvdS with specific binding sites in the promoter region of cas1. Furthermore, activation of the CRISPR-Cas system under iron-depleted conditions increases horizontal gene transfer (HGT) interference and adaptation. The PvdS activation of the CRISPR-Cas system under iron limitation highlights the versatility of the P. aeruginosa in multitasking its regulatory machinery to integrate multiple stress factors.ImportanceP. aeruginosa infects a wide range of host organisms and adapts to various environmental stress factors such as iron limitation due to its elaborate regulatory system. P aeruginosa possesses the type I-F CRISPR-Cas system as a defense mechanism against phages infection and HGT. This work highlights the ability of P. aeruginosa to multitask its iron regulatory system to control the CRISPR-Cas system under a physiologically relevant stress factor such as iron limitation where the bacteria are vulnerable to phage infection. It also adds to the knowledge of the regulation of the CRISPR-Cas system in bacteria and presents a possible target that could prevent the emergence of phage resistance via the CRISPR-Cas system during the development of phage therapy.

scholarly journals The Two-Component Regulators GacS and GacA Influence Accumulation of the Stationary-Phase Sigma Factor ςS and the Stress Response in Pseudomonas fluorescensPf-5

1998 ◽  
Vol 180 (24) ◽  
pp. 6635-6641 ◽  
Author(s):  
Cheryl A. Whistler ◽  
Nathan A. Corbell ◽  
Alain Sarniguet ◽  
Walter Ream ◽  
Joyce E. Loper
Keyword(s):  
Oxidative Stress ◽  
Stress Response ◽  
Stationary Phase ◽  
Sigma Factor ◽  
Antibiotic Production ◽  
Regulatory System ◽  
Response Regulators ◽  
Global Regulators ◽  
Regulatory Cascade ◽  
Two Component

ABSTRACT Three global regulators are known to control antibiotic production by Pseudomonas fluorescens. A two-component regulatory system comprised of the sensor kinase GacS (previously called ApdA or LemA) and GacA, a member of the FixJ family of response regulators, is required for antibiotic production. A mutation inrpoS, which encodes the stationary-phase sigma factor ςS, differentially affects antibiotic production and reduces the capacity of stationary-phase cells of P. fluorescens to survive exposure to oxidative stress. ThegacA gene of P. fluorescens Pf-5 was isolated, and the influence of gacS and gacA onrpoS transcription, ςS levels, and oxidative stress response of Pf-5 was determined. We selected a gacAmutant of Pf-5 that contained a single nucleotide substitution within a predicted α-helical region, which is highly conserved among the FixJ family of response regulators. At the entrance to stationary phase, ςS content in gacS and gacAmutants of Pf-5 was less than 20% of the wild-type level. Transcription of rpoS, assessed with anrpoS-lacZ transcriptional fusion, was positively influenced by GacS and GacA, an effect that was most evident at the transition between exponential growth and stationary phase. Mutations ingacS and gacA compromised the capacity of stationary-phase cells of Pf-5 to survive exposure to oxidative stress. The results of this study provide evidence for the predominant roles of GacS and GacA in the regulatory cascade controlling stress response and antifungal metabolite production in P. fluorescens.

scholarly journals An Extracytoplasmic Function Sigma Factor Acts as a General Stress Response Regulator in Sinorhizobium meliloti

2007 ◽  
Vol 189 (11) ◽  
pp. 4204-4216 ◽  
Author(s):  
Laurent Sauviac ◽  
Heinui Philippe ◽  
Kounthéa Phok ◽  
Claude Bruand
Keyword(s):  
Stress Response ◽  
Stationary Phase ◽  
Stress Responses ◽  
Sigma Factor ◽  
Sinorhizobium Meliloti ◽  
In Planta ◽  
General Stress Response ◽  
Stress Response Genes ◽  
General Stress

ABSTRACT Sinorhizobium meliloti genes transcriptionally up-regulated after heat stress, as well as upon entry into stationary phase, were identified by microarray analyses. Sixty stress response genes were thus found to be up-regulated under both conditions. One of them, rpoE2 (smc01506), encodes a putative extracytoplasmic function (ECF) sigma factor. We showed that this sigma factor controls its own transcription and is activated by various stress conditions, including heat and salt, as well as entry into stationary phase after either carbon or nitrogen starvation. We also present evidence that the product of the gene cotranscribed with rpoE2 negatively regulates RpoE2 activity, and we therefore propose that it plays the function of anti-sigma factor. By combining transcriptomic, bioinformatic, and quantitative reverse transcription-PCR analyses, we identified 44 RpoE2-controlled genes and predicted the number of RpoE2 targets to be higher. Strikingly, more than one-third of the 60 stress response genes identified in this study are RpoE2 targets. Interestingly, two genes encoding proteins with known functions in stress responses, namely, katC and rpoH2, as well as a second ECF-encoding gene, rpoE5, were found to be RpoE2 regulated. Altogether, these data suggest that RpoE2 is a major global regulator of the general stress response in S. meliloti. Despite these observations, and although this sigma factor is well conserved among alphaproteobacteria, no in vitro nor in planta phenotypic difference from the wild-type strain could be detected for rpoE2 mutants. This therefore suggests that other important actors in the general stress response have still to be identified in S. meliloti.

scholarly journals A genomic island of Streptomyces coelicolor with the self-contained regulon of an ECF sigma factor

2018 ◽  
Author(s):  
Camilla M. Kao ◽  
Nitsara Karoonuthaisiri ◽  
David Weaver ◽  
Jonathan A. Vroom ◽  
Shuning A. Gai ◽  
...  
Keyword(s):  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Sigma Factor ◽  
Genomic Island ◽  
Streptomyces Coelicolor ◽  
Sigma Factors ◽  
Genomic Islands ◽  
Biologically Active ◽  
Transcriptional Unit ◽  
Ecf Sigma Factor

AbstractStreptomycetes constitute the largest genus of actinobacteria, living predominantly in soil and decaying vegetation. The bacteria are widely known for their filamentous morphologies and their capacity to synthesize antibiotics and other biologically active molecules. More than a decade ago, we and others identified 22 genomic islands thatStreptomyces coelicolorM145 possesses and otherStreptomycesstrains lack. One of these genomic islands, Genomic Island (GI) 6, encodes an extracytoplasmic function (ECF) sigma factor that we were characterizing in separate work. Here we report that artificial induction of the ECF sigma factor, which is encoded by SCO3450, causes the transcription of approximately one-fourth of GI 6, or ~26 mostly contiguous genes, to increase. More than half of the regulon encodes putative enzymes involved in small molecule metabolism. A putative haloacid dehalogenase is present. Genes encoding two putative anti-sigma factors flank SCO3450, the three genes residing within the regulon. Our data suggest that the ECF sigma factor and its regulon are a self-contained transcriptional unit that can be transferred by horizontal gene transfer. To our knowledge, only one other example has been identified of an ECF sigma factor and its contiguous regulon appearing to be transferrable by horizontal gene transfer [18,19]. Because the regulon appears not to be induced by the 44 growth conditions recently examined by Byung-Kwan Cho and colleagues [20], if it confers fitness toS. coelicolor, the regulon likely does so in as-yet unknown situations. Those situations might range from scavenging to detoxification to even communication within microbial communities.IMPORTANCEStreptomycesbacteria grow as hyphae that colonize soil and differentiate into spores when nutrients become scarce. In their terrestrial habitats, the bacteria encounter diverse conditions. Presumably so that the bacteria can cope with those conditions, the chromosomes of streptomycetes are highly dynamic, varying greatly in structure not only between species but also between closely related strains of a single species. The bacteria also have large numbers of extracytoplasmic function (ECF) sigma factors, which undoubtedly help the microorganisms respond to the plethora of challenges coming from the environment. This work illustrates these two threads ofStreptomycesbiology dovetailing: Genetic adaptability through horizontal gene transfer seems to have enabledStreptomyces coelicolorto acquire a self-contained transcriptional unit that consists of an ECF sigma factor and its regulon. The suggested facile movement of the regulon between microbial hosts indicates the value of the metabolism of small molecules possibly mediated by the regulon.

scholarly journals A Mycobacterial Extracytoplasmic Sigma Factor Involved in Survival following Heat Shock and Oxidative Stress

1999 ◽  
Vol 181 (14) ◽  
pp. 4266-4274 ◽  
Author(s):  
Norvin D. Fernandes ◽  
Qi-long Wu ◽  
Dequan Kong ◽  
Xiaoling Puyang ◽  
Sumeet Garg ◽  
...  
Keyword(s):  
Heat Shock ◽  
Sigma Factor ◽  
Transcriptional Start Site ◽  
Cumene Hydroperoxide ◽  
Single Copy ◽  
Sigma Factors ◽  
Gene Encoding ◽  
Promoter Sequences ◽  
Ecf Sigma Factor

ABSTRACT Extracytoplasmic function (ECF) sigma factors are a heterogeneous group of alternative sigma factors that regulate gene expression in response to a variety of conditions, including stress. We previously characterized a mycobacterial ECF sigma factor, SigE, that contributes to survival following several distinct stresses. A gene encoding a closely related sigma factor, sigH, was cloned fromMycobacterium tuberculosis and Mycobacterium smegmatis. A single copy of this gene is present in these and other fast- and slow-growing mycobacteria, including M. fortuitum and M. avium. While the M. tuberculosis and M. smegmatis sigH genes encode highly similar proteins, there are multiple differences in adjacent genes. The single in vivo transcriptional start site identified inM. smegmatis and one of two identified in M. bovis BCG were found to have −35 promoter sequences that match the ECF-dependent −35 promoter consensus. Expression from these promoters was strongly induced by 50°C heat shock. In comparison to the wild type, an M. smegmatis sigH mutant was found to be more susceptible to cumene hydroperoxide stress but to be similar in logarithmic growth, stationary-phase survival, and survival following several other stresses. Survival of an M. smegmatis sigH sigE double mutant was found to be markedly decreased following 53°C heat shock and following exposure to cumene hydroperoxide. Expression of the second gene in the sigH operon is required for complementation of the sigH stress phenotypes. SigH is an alternative sigma factor that plays a role in the mycobacterial stress response.

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