scholarly journals Genetic Evidence for the Actin Homolog Gene mreBH and the Bacitracin Resistance Gene bcrC as Targets of the Alternative Sigma Factor SigI of Bacillus subtilis

2007 ◽  
Vol 190 (5) ◽  
pp. 1561-1567 ◽  
Author(s):  
Chi-Ling Tseng ◽  
Gwo-Chyuan Shaw
Keyword(s):  
Bacillus Subtilis ◽  
Heat Shock ◽  
Resistance Gene ◽  
Sigma Factor ◽  
Promoter Region ◽  
Consensus Sequence ◽  
Regulatory Region ◽  
Primer Extension ◽  
Vector System ◽  
Alternative Sigma Factor

ABSTRACT The Bacillus subtilis sigI gene, which is a member of the class VI heat shock genes of the B. subtilis heat shock stimulon, encodes an alternative sigma factor whose regulon is poorly defined. In this study, by using a binary vector system, we showed that B. subtilis SigI could drive expression of a transcriptional fusion between the sigI regulatory region from Bacillus licheniformis, Bacillus sp. strain NRRL B-14911, B. subtilis, or Bacillus thuringiensis and the xylE reporter gene in B. subtilis. The transcriptional initiation sites of these fusions in B. subtilis were mapped by primer extension analyses. A putative consensus promoter sequence probably recognized by the B. subtilis SigI was thus deduced. Using a consensus sequence-based search procedure, we found putative σI promoters preceding the actin homolog gene mreBH and the bacitracin resistance gene bcrC of B. subtilis. Overexpression of the B. subtilis sigI gene could specifically stimulate expression of both an mreBH promoter region-bgaB fusion and a bcrC promoter region-bgaB fusion. Expression of these two fusions at the amyE locus of the B. subtilis chromosome was heat inducible and SigI dependent as revealed by sigI gene disruption experiments. Primer extension analysis showed that the identified mreBH and bcrC transcriptional start sites were at appropriate distances from their σI promoter elements. This further supports the notion that SigI can directly regulate mreBH and bcrC expression. Taken together, these results strongly suggest that mreBH and bcrC are new members of the SigI regulon.

scholarly journals Transcriptional Regulation and Mechanism of SigN (ZpdN), a pBS32-Encoded Sigma Factor in Bacillus subtilis

mBio ◽  
2019 ◽  
Vol 10 (5) ◽  
Author(s):  
Aisha T. Burton ◽  
Aaron DeLoughery ◽  
Gene-Wei Li ◽  
Daniel B. Kearns
Keyword(s):  
Dna Damage ◽  
Bacillus Subtilis ◽  
Sigma Factor ◽  
Consensus Sequence ◽  
Sigma Factors ◽  
Sequencing Analysis ◽  
Dependent Manner ◽  
Content Type ◽  
Alternative Sigma Factors ◽  
Bona Fide

ABSTRACT Laboratory strains of Bacillus subtilis encode many alternative sigma factors, each dedicated to expressing a unique regulon such as those involved in stress resistance, sporulation, and motility. The ancestral strain of B. subtilis also encodes an additional sigma factor homolog, ZpdN, not found in lab strains due to being encoded on the large, low-copy-number plasmid pBS32, which was lost during domestication. DNA damage triggers pBS32 hyperreplication and cell death in a manner that depends on ZpdN, but how ZpdN mediates these effects is unknown. Here, we show that ZpdN is a bona fide sigma factor that can direct RNA polymerase to transcribe ZpdN-dependent genes, and we rename ZpdN SigN accordingly. Rend-seq (end-enriched transcriptome sequencing) analysis was used to determine the SigN regulon on pBS32, and the 5′ ends of transcripts were used to predict the SigN consensus sequence. Finally, we characterize the regulation of SigN itself and show that it is transcribed by at least three promoters: PsigN1, a strong SigA-dependent LexA-repressed promoter; PsigN2, a weak SigA-dependent constitutive promoter; and PsigN3, a SigN-dependent promoter. Thus, in response to DNA damage SigN is derepressed and then experiences positive feedback. How cells die in a pBS32-dependent manner remains unknown, but we predict that death is the product of expressing one or more genes in the SigN regulon. IMPORTANCE Sigma factors are utilized by bacteria to control and regulate gene expression. Some sigma factors are activated during times of stress to ensure the survival of the bacterium. Here, we report the presence of a sigma factor that is encoded on a plasmid that leads to cellular death after DNA damage.

scholarly journals Transient Association of an Alternative Sigma Factor, ComX, with RNA Polymerase during the Period of Competence for Genetic Transformation in Streptococcus pneumoniae

2003 ◽  
Vol 185 (1) ◽  
pp. 349-358 ◽  
Author(s):  
Ping Luo ◽  
Donald A. Morrison
Keyword(s):  
Streptococcus Pneumoniae ◽  
Rna Polymerase ◽  
Sigma Factor ◽  
Consensus Sequence ◽  
Molar Ratio ◽  
Alternative Sigma Factor ◽  
Dna Uptake ◽  
Promoter Regions ◽  
Overexpression Strain ◽  
Peptide Pheromone

ABSTRACT Natural transformation in Streptococcus pneumoniae is regulated by a quorum-sensing system that acts through accumulation and sensing of a peptide pheromone (competence-stimulating peptide [CSP]) to control many competence-specific genes acting in DNA uptake, processing, and integration. The period of competence induced by CSP lasts only 15 min (quarter-height peak width). The recently identified regulator ComX is required for the CSP-dependent expression of many competence-specific genes that share an unusual consensus sequence (TACGAATA) at their promoter regions. To test the hypothesis that this regulator acts as a transient alternative sigma factor, ComX was purified from an Escherichia coli overexpression strain and core RNA polymerase was purified from a comX-deficient S. pneumoniae strain. The reconstituted ComX-polymerase holoenzyme produced transcripts for the competence-specific genes ssbB, cinA, cglA, celA, and dalA and was inhibited by anti-ComX antibody, but not by anti-σ70 antibody. Western blotting using antibodies specific for ComX, σ70, and poly-His revealed a transient presence of ComX for a period of 15 to 20 min after CSP treatment, while RNA polymerase remained at a constant level and σA remained between 60 and 125% of its normal level. ComX reached a molar ratio to RNA polymerase of at least 1.5. We conclude that ComX is unstable and acts as a competence-specific sigma factor.

scholarly journals Robust Heat Shock Response in Chlamydia Lacking a Typical Heat Shock Sigma Factor

2022 ◽  
Vol 12 ◽  
Author(s):  
Yehong Huang ◽  
Wurihan Wurihan ◽  
Bin Lu ◽  
Yi Zou ◽  
Yuxuan Wang ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Heat Shock ◽  
Heat Shock Response ◽  
Sigma Factor ◽  
Target Genes ◽  
Sigma Factors ◽  
Survival Strategies ◽  
Alternative Sigma Factor ◽  
Metabolism Enzymes ◽  
Shock Response

Cells reprogram their transcriptome in response to stress, such as heat shock. In free-living bacteria, the transcriptomic reprogramming is mediated by increased DNA-binding activity of heat shock sigma factors and activation of genes normally repressed by heat-induced transcription factors. In this study, we performed transcriptomic analyses to investigate heat shock response in the obligate intracellular bacterium Chlamydia trachomatis, whose genome encodes only three sigma factors and a single heat-induced transcription factor. Nearly one-third of C. trachomatis genes showed statistically significant (≥1.5-fold) expression changes 30 min after shifting from 37 to 45°C. Notably, chromosomal genes encoding chaperones, energy metabolism enzymes, type III secretion proteins, as well as most plasmid-encoded genes, were differentially upregulated. In contrast, genes with functions in protein synthesis were disproportionately downregulated. These findings suggest that facilitating protein folding, increasing energy production, manipulating host activities, upregulating plasmid-encoded gene expression, and decreasing general protein synthesis helps facilitate C. trachomatis survival under stress. In addition to relieving negative regulation by the heat-inducible transcriptional repressor HrcA, heat shock upregulated the chlamydial primary sigma factor σ66 and an alternative sigma factor σ28. Interestingly, we show for the first time that heat shock downregulates the other alternative sigma factor σ54 in a bacterium. Downregulation of σ54 was accompanied by increased expression of the σ54 RNA polymerase activator AtoC, thus suggesting a unique regulatory mechanism for reestablishing normal expression of select σ54 target genes. Taken together, our findings reveal that C. trachomatis utilizes multiple novel survival strategies to cope with environmental stress and even to replicate. Future strategies that can specifically target and disrupt Chlamydia’s heat shock response will likely be of therapeutic value.

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 Role of autoregulation and relative synthesis of operon partners in alternative sigma factor networks

2015 ◽  
Author(s):  
Jatin Narula ◽  
Abhinav Tiwari ◽  
Oleg A. Igoshin
Keyword(s):  
Bacillus Subtilis ◽  
Stress Response ◽  
Negative Feedback ◽  
Sigma Factor ◽  
Critical Role ◽  
Sigma Factors ◽  
Alternative Sigma Factor ◽  
Negative Feedback Regulation ◽  
Alternative Sigma Factors

SummaryDespite the central role of alternative sigma factors in bacterial stress response and virulence their regulation remains incompletely understood. Here we investigate one of the best-studied examples of alternative sigma factors: the σBnetwork that controls the general stress response ofBacillus subtilisto uncover widely relevant general design principles that describe the structure-function relationship of alternative sigma factor regulatory networks. We show that the relative stoichiometry of the synthesis rates of σB, its anti-sigma factor RsbW and the anti-anti-sigma factor RsbV plays a critical role in shaping the network behavior by forcing the σBnetwork to function as an ultrasensitive negative feedback loop. We further demonstrate how this negative feedback regulation insulates alternative sigma factor activity from competition with the housekeeping sigma factor for RNA polymerase and allows multiple stress sigma factors to function simultaneously with little competitive interference.Major Subject Areas:Computational and systems biology, Microbiology & Infectious diseaseResearch Organism:Bacillus subtilis

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