scholarly journals Analysis of the mRNAs in Spores ofBacillus subtilis

2019 ◽  
Vol 201 (9) ◽  
Author(s):  
George Korza ◽  
Emily Camilleri ◽  
Joshua Green ◽  
Janelle Robinson ◽  
Katja Nagler ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Sigma Factor ◽  
Large Scale ◽  
Rna Synthesis ◽  
Great Majority ◽  
Rna Seq ◽  
Ofbacillus Subtilis ◽  
Content Type ◽  
Almost All ◽  
Made In

ABSTRACTLarge-scale shotgun sequencing (RNA-seq) analysis of mRNAs in dormantBacillus subtilisspores prepared on plates or in liquid generally found the same ∼46 abundant mRNA species, with >250 mRNAs detected at much lower abundances. Knowledge of the amount of phosphate in a singleB. subtilisspore allowed calculation of the amount of mRNA in an individual spore as ∼106 nucleotides (nt). Given the levels of abundant spore mRNAs compared to those of other mRNAs, it was calculated that the great majority of low-abundance mRNAs are present in only small fractions of spores in populations. Almost all of the most abundant spore mRNAs are encoded by genes expressed late in sporulation in the developing spore under the control of the forespore-specific RNA polymerase sigma factor, σG, and most of the encoded proteins are in spores. Levels of the most abundant spore mRNAs were also relatively stable for a week at 4°C after spore harvest. RNA-seq analysis of mRNAs in highly purified and less-well-purified spores made in liquid, as well as from spores that were chemically decoated to remove possible contaminating mRNA, indicated that low-abundance mRNAs in spores were not contaminants in purified spore preparations, and several sources of low-abundance mRNAs in spores are suggested. The function of at least the great majority of spore mRNAs seems most likely to be the generation of ribonucleotides for new RNA synthesis by their degradation early in spore revival.IMPORTANCEPrevious work indicates that dormantBacillus subtilisspores have many hundreds of mRNAs, some of which are suggested to play roles in spores’ “return to life” or revival. The present work finds only ∼46 mRNAs at ≥1 molecule spore, with others in only fractions of spores in populations, often very small fractions. Less-abundant spore mRNAs are not contaminants in spore preparations, but how spores accumulate them is not clear. Almost all abundant spore mRNAs are synthesized in the developing spore late in its development, most encode proteins in spores, and abundant mRNAs in spores are relatively stable at 4°C. These findings will have a major impact on thinking about the roles that spore mRNAs may play in spore revival.

scholarly journals A Mutation in the Bacillus subtilis rsbU Gene That Limits RNA Synthesis during Sporulation

2017 ◽  
Vol 199 (14) ◽  
Author(s):  
David M. Rothstein ◽  
David Lazinski ◽  
Marcia S. Osburne ◽  
Abraham L. Sonenshein
Keyword(s):  
Bacillus Subtilis ◽  
Rna Polymerase ◽  
Sigma Factor ◽  
Rna Synthesis ◽  
Bacterial Species ◽  
Ethanol Stress ◽  
Temperature Sensitive ◽  
Content Type ◽  
Promoter Recognition ◽  
Bacillis Subtilis

ABSTRACT Mutants of Bacillis subtilis that are temperature sensitive for RNA synthesis during sporulation were isolated after selection with a 32P suicide agent. Whole-genome sequencing revealed that two of the mutants carried an identical lesion in the rsbU gene, which encodes a phosphatase that indirectly activates SigB, the stress-responsive RNA polymerase sigma factor. The mutation appeared to cause RsbU to be hyperactive, because the mutants were more resistant than the parent strain to ethanol stress. In support of this hypothesis, pseudorevertants that regained wild-type levels of sporulation at high temperature had secondary mutations that prevented expression of the mutant rsbU gene. The properties of these RsbU mutants support the idea that activation of SigB diminishes the bacterium's ability to sporulate. IMPORTANCE Most bacterial species encode multiple RNA polymerase promoter recognition subunits (sigma factors). Each sigma factor directs RNA polymerase to different sets of genes; each gene set typically encodes proteins important for responses to specific environmental conditions, such as changes in temperature, salt concentration, and nutrient availability. A selection for mutants of Bacillus subtilis that are temperature sensitive for RNA synthesis during sporulation unexpectedly yielded strains with a point mutation in rsbU, a gene that encodes a protein that normally activates sigma factor B (SigB) under conditions of salt stress. The mutation appears to cause RsbU, and therefore SigB, to be active inappropriately, thereby inhibiting, directly or indirectly, the ability of the cells to transcribe sporulation genes.

scholarly journals Levels and Characteristics of mRNAs in Spores of Firmicute Species

2021 ◽  
Author(s):  
Brandon Byrd ◽  
Emily Camilleri ◽  
George Korza ◽  
D. Levi Craft ◽  
Joshua Green ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Rna Polymerase ◽  
Rna Synthesis ◽  
Great Majority ◽  
Mrna Levels ◽  
Geobacillus Stearothermophilus ◽  
Rna Seq ◽  
Cell Compartment ◽  
Major Function

Spores of Firmicute species contain 100s of mRNAs, whose major function in Bacillus subtilis is to provide ribonucleotides for new RNA synthesis when spores germinate. To determine if this is a general phenomenon, RNA was isolated from spores of multiple Firmicute species and relative mRNA levels determined by RNA-seq. Determination of RNA levels in single spores allowed calculation of RNA nt/spore, and assuming mRNA is 3% of spore RNA indicated that only ∼6% of spore mRNAs were present at > 1/spore. Bacillus subtilis, Bacillus atrophaeus and Clostridiodes difficile spores had 49, 42 and 51 mRNAs at > 1/spore, numbers of mRNAs at ≥ 1/spore were ∼10 to 50% higher in Geobacillus stearothermophilus and Bacillus thuringiensis Al Hakam spores, and ∼4-fold higher in Bacillus megaterium spores. In all species some to many abundant spore mRNAs: i) were transcribed by RNA polymerase with forespore-specific σ factors; ii) encoded proteins that were homologs of those encoded by abundant B. subtilis spore mRNAs and are proteins in dormant spores; and iii) a few were likely transcribed in the mother cell compartment of the sporulating cell. Analysis of the coverage of RNA-seq reads on mRNAs from all species suggested that abundant spore mRNAs were fragmented, as was confirmed by RT-qPCR analysis of abundant B. subtilis and C. difficile spore mRNAs. These data add to evidence indicating that the function of at least the great majority of mRNAs in all Firmicute spores is to be degraded to generate ribonucleotides for new RNA synthesis when spores germinate. Importance Only ∼6% of mRNAs in spores of six Firmicute species are at ≥1 molecule/spore, many abundant spore mRNAs encode proteins similar to B. subtilis spore proteins, and some abundant B. subtilis and C. difficile spore mRNAs were fragmented. Most of the abundant B. subtilis and other Bacillales spore mRNAs are transcribed under control of the forespore-specific RNA polymerase σ factors, F or G, and these results may stimulate transcription analyses in developing spores of species other than B. subtilis. These findings, plus the absence of key nucleotide biosynthetic enzymes in spores, suggest that Firmicute spores’ abundant mRNAs are not translated when spores germinate, but instead are degraded to generate ribonucleotides for new RNA synthesis by the germinated spore.

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 Applications of Bacillus subtilis Spores in Biotechnology and Advanced Materials

2020 ◽  
Vol 86 (17) ◽  
Author(s):  
Xiaopei Zhang ◽  
Amal Al-Dossary ◽  
Myer Hussain ◽  
Peter Setlow ◽  
Jiahe Li
Keyword(s):  
Bacillus Subtilis ◽  
Large Scale ◽  
Genetic Manipulation ◽  
Industrial Applications ◽  
Advanced Materials ◽  
Content Type ◽  
Interdisciplinary Approaches ◽  
Food Shortages ◽  
Material Sciences ◽  
Basic Studies

ABSTRACT The bacterium Bacillus subtilis has long been an important subject for basic studies. However, this organism has also had industrial applications due to its easy genetic manipulation, favorable culturing characteristics for large‐scale fermentation, superior capacity for protein secretion, and generally recognized as safe (GRAS) status. In addition, as the metabolically dormant form of B. subtilis, its spores have attracted great interest due to their extreme resistance to many environmental stresses, which makes spores a novel platform for a variety of applications. In this review, we summarize both conventional and emerging applications of B. subtilis spores, with a focus on how their unique characteristics have led to innovative applications in many areas of technology, including generation of stable and recyclable enzymes, synthetic biology, drug delivery, and material sciences. Ultimately, this review hopes to inspire the scientific community to leverage interdisciplinary approaches using spores to address global concerns about food shortages, environmental protection, and health care.

scholarly journals Role of Dipicolinic Acid in the Germination, Stability, and Viability of Spores of Bacillus subtilis

2008 ◽  
Vol 190 (14) ◽  
pp. 4798-4807 ◽  
Author(s):  
Anil Magge ◽  
Amanda C. Granger ◽  
Paul G. Wahome ◽  
Barbara Setlow ◽  
Venkata R. Vepachedu ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Small Molecules ◽  
Spore Germination ◽  
Dipicolinic Acid ◽  
Great Majority ◽  
Lytic Enzyme ◽  
Spore Proteins ◽  
Low Levels ◽  
Made In

ABSTRACT Spores of Bacillus subtilis spoVF strains that cannot synthesize dipicolinic acid (DPA) but take it up during sporulation were prepared in medium with various DPA concentrations, and the germination and viability of these spores as well as the DPA content in individual spores were measured. Levels of some other small molecules in DPA-less spores were also measured. These studies have allowed the following conclusions. (i) Spores with no DPA or low DPA levels that lack either the cortex-lytic enzyme (CLE) SleB or the receptors that respond to nutrient germinants could be isolated but were unstable and spontaneously initiated early steps in spore germination. (ii) Spores that lacked SleB and nutrient germinant receptors and also had low DPA levels were more stable. (iii) Spontaneous germination of spores with no DPA or low DPA levels was at least in part via activation of SleB. (iv) The other redundant CLE, CwlJ, was activated only by the release of high levels of DPA from spores. (v) Low levels of DPA were sufficient for the viability of spores that lacked most α/β-type small, acid-soluble spore proteins. (vi) DPA levels accumulated in spores prepared in low-DPA-containing media varied greatly between individual spores, in contrast to the presence of more homogeneous DPA levels in individual spores made in media with high DPA concentrations. (vii) At least the great majority of spores of several spoVF strains that contained no DPA also lacked other major spore small molecules and had gone through some of the early reactions in spore germination.

scholarly journals ZpdN, a Plasmid-Encoded Sigma Factor Homolog, Induces pBS32-Dependent Cell Death in Bacillus subtilis

2016 ◽  
Vol 198 (21) ◽  
pp. 2975-2984 ◽  
Author(s):  
B.-E. Myagmarjav ◽  
M. A. Konkol ◽  
J. Ramsey ◽  
S. Mukhopadhyay ◽  
D. B. Kearns
Keyword(s):  
Cell Death ◽  
Bacillus Subtilis ◽  
Mitomycin C ◽  
Sigma Factor ◽  
Natural Transformation ◽  
Potent Inhibitor ◽  
Dna Uptake ◽  
Content Type ◽  
Dependent Cell ◽  
Necessary And Sufficient

ABSTRACTThe ancestralBacillus subtilisstrain 3610 contains an 84-kb plasmid called pBS32 that was lost during domestication of commonly used laboratory derivatives. Here we demonstrate that pBS32, normally present at 1 or 2 copies per cell, increases in copy number nearly 100-fold when cells are treated with the DNA-damaging agent mitomycin C. Mitomycin C treatment also caused cell lysis dependent on pBS32-borne prophage genes. ZpdN, a sigma factor homolog encoded by pBS32, was required for the plasmid response to DNA damage, and artificial expression of ZpdN was sufficient to induce pBS32 hyperreplication and cell death. Plasmid DNA released by cell death was protected by the capsid protein ZpbH, suggesting that the plasmid was packaged into a phagelike particle. The putative particles were further indicated by CsCl sedimentation but were not observed by electron microscopy and were incapable of killingB. subtiliscells extracellularly. We hypothesize that pBS32-mediated cell death releases a phagelike particle that is defective and unstable.IMPORTANCEProphages are phage genomes stably integrated into the host bacterium's chromosome and less frequently are maintained as extrachromosomal plasmids. Here we report that the extrachromosomal plasmid pBS32 ofBacillus subtilisencodes a prophage that, when activated, kills the host. pBS32 also encodes both the sigma factor homolog ZpdN that is necessary and sufficient for prophage induction and the protein ComI, which is a potent inhibitor of DNA uptake by natural transformation. We provide evidence that the entire pBS32 sequence may be part of the prophage and thus that competence inhibition may be linked to lysogeny.

scholarly journals A Membrane-Embedded Amino Acid Couples the SpoIIQ Channel Protein to Anti-Sigma Factor Transcriptional Repression during Bacillus subtilis Sporulation

2016 ◽  
Vol 198 (9) ◽  
pp. 1451-1463 ◽  
Author(s):  
Kelly A. Flanagan ◽  
Joseph D. Comber ◽  
Elizabeth Mearls ◽  
Colleen Fenton ◽  
Anna F. Wang Erickson ◽  
...  
Keyword(s):  
Gene Expression ◽  
Bacillus Subtilis ◽  
Amino Acid ◽  
Sigma Factor ◽  
Late Gene ◽  
Late Gene Expression ◽  
Gene Encoding ◽  
Content Type ◽  
Regulatory Circuit ◽  
Gene Regulatory

ABSTRACTSpoIIQ is an essential component of a channel connecting the developing forespore to the adjacent mother cell duringBacillus subtilissporulation. This channel is generally required for late gene expression in the forespore, including that directed by the late-acting sigma factor σG. Here, we present evidence that SpoIIQ also participates in a previously unknown gene regulatory circuit that specifically represses expression of the gene encoding the anti-sigma factor CsfB, a potent inhibitor of σG. ThecsfBgene is ordinarily transcribed in the forespore only by the early-acting sigma factor σF. However, in a mutant lacking the highly conserved SpoIIQ transmembrane amino acid Tyr-28,csfBwas also aberrantly transcribed later by σG, the very target of CsfB inhibition. This regulation ofcsfBby SpoIIQ Tyr-28 is specific, given that the expression of other σF-dependent genes was unaffected. Moreover, we identified a conserved element within thecsfBpromoter region that is both necessary and sufficient for SpoIIQ Tyr-28-mediated inhibition. These results indicate that SpoIIQ is a bifunctional protein that not only generally promotes σGactivity in the forespore as a channel component but also specifically maximizes σGactivity as part of a gene regulatory circuit that represses σG-dependent expression of its own inhibitor, CsfB. Finally, we demonstrate that SpoIIQ Tyr-28 is required for the proper localization and stability of the SpoIIE phosphatase, raising the possibility that these two multifunctional proteins cooperate to fine-tune developmental gene expression in the forespore at late times.IMPORTANCECellular development is orchestrated by gene regulatory networks that activate or repress developmental genes at the right time and place. Late gene expression in the developingBacillus subtilisspore is directed by the alternative sigma factor σG. The activity of σGrequires a channel apparatus through which the adjacent mother cell provides substrates that generally support gene expression. Here we report that the channel protein SpoIIQ also specifically maximizes σGactivity as part of a previously unknown regulatory circuit that prevents σGfrom activating transcription of the gene encoding its own inhibitor, the anti-sigma factor CsfB. The discovery of this regulatory circuit significantly expands our understanding of the gene regulatory network controlling late gene expression in the developingB. subtilisspore.

scholarly journals BSGatlas: a unified Bacillus subtilis genome and transcriptome annotation atlas with enhanced information access

2021 ◽  
Vol 7 (2) ◽  
Author(s):  
Adrian Sven Geissler ◽  
Christian Anthon ◽  
Ferhat Alkan ◽  
Enrique González-Tortuero ◽  
Line Dahl Poulsen ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Type Species ◽  
Large Scale ◽  
Information Access ◽  
Model Systems ◽  
Transcription Start ◽  
Content Type ◽  
Link Type ◽  
Genome Wide ◽  
Transcript Map

A large part of our current understanding of gene regulation in Gram-positive bacteria is based on Bacillus subtilis , as it is one of the most well studied bacterial model systems. The rapid growth in data concerning its molecular and genomic biology is distributed across multiple annotation resources. Consequently, the interpretation of data from further B. subtilis experiments becomes increasingly challenging in both low- and large-scale analyses. Additionally, B. subtilis annotation of structured RNA and non-coding RNA (ncRNA), as well as the operon structure, is still lagging behind the annotation of the coding sequences. To address these challenges, we created the B. subtilis genome atlas, BSGatlas, which integrates and unifies multiple existing annotation resources. Compared to any of the individual resources, the BSGatlas contains twice as many ncRNAs, while improving the positional annotation for 70 % of the ncRNAs. Furthermore, we combined known transcription start and termination sites with lists of known co-transcribed gene sets to create a comprehensive transcript map. The combination with transcription start/termination site annotations resulted in 717 new sets of co-transcribed genes and 5335 untranslated regions (UTRs). In comparison to existing resources, the number of 5′ and 3′ UTRs increased nearly fivefold, and the number of internal UTRs doubled. The transcript map is organized in 2266 operons, which provides transcriptional annotation for 92 % of all genes in the genome compared to the at most 82 % by previous resources. We predicted an off-target-aware genome-wide library of CRISPR–Cas9 guide RNAs, which we also linked to polycistronic operons. We provide the BSGatlas in multiple forms: as a website (https://rth.dk/resources/bsgatlas/), an annotation hub for display in the UCSC genome browser, supplementary tables and standardized GFF3 format, which can be used in large scale -omics studies. By complementing existing resources, the BSGatlas supports analyses of the B. subtilis genome and its molecular biology with respect to not only non-coding genes but also genome-wide transcriptional relationships of all genes.

scholarly journals Viral and host transcriptomes in SARS-CoV-2 infected human lung cells

2021 ◽  
Author(s):  
Xuefeng Wang ◽  
Yudong Zhao ◽  
Feihu Yan ◽  
Tiecheng Wang ◽  
Weiyang Sun ◽  
...  
Keyword(s):  
Large Scale ◽  
Rna Synthesis ◽  
Viral Rna ◽  
Viral Gene ◽  
Envelope Gene ◽  
Genome Replication ◽  
Content Type ◽  
Nucleocapsid Gene ◽  
Human Lung Cells ◽  
Synthesis Strategy

Coronaviruses are commonly characterized by a unique discontinuous RNA transcriptional synthesis strategy guided by transcription-regulating sequences (TRSs). However, the details of RNA synthesis in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have not been fully elucidated. Here, we present a time-scaled, gene-comparable transcriptome of SARS-CoV-2, demonstrating that ACGAAC functions as a core TRS guiding the discontinuous RNA synthesis of SARS-CoV-2 from a holistic perspective. During infection, viral transcription, rather than genome replication, dominates all viral RNA synthesis activities. The most highly expressed viral gene is the nucleocapsid gene, followed by ORF7 and ORF3 genes, while the envelope gene shows the lowest expression. Host transcription dysregulation keeps exacerbating after viral RNA synthesis achieves to the top. The most enriched host pathways are metabolism-related. Two of them (cholesterol and valine metabolism) affect viral replication in reverse. Furthermore, the activation of numerous cytokines emerges before the large-scale viral RNA synthesis. Importance SARS-CoV-2 is responsible for the current severe global health emergency that began at the end of 2019. Although the universal transcriptional strategies of coronaviruses are preliminarily understood, the details of RNA synthesis, especially the time-matched transcription level of each SARS-CoV-2 gene and the principles of subgenomic mRNA synthesis, are not clear. The coterminal subgenomic mRNAs of SARS-CoV-2 present obstacles in identifying the expression of most genes by PCR-based methods, which is exacerbated by the lack of related antibodies. Moreover, SARS-CoV-2-related metabolic imbalance and cytokine storm are receiving increasing attention from both clinical and mechanistic perspectives. Our transcriptomic research provides information on both viral RNA synthesis and host responses, in which the transcription-regulating sequences and transcription levels of viral genes are demonstrated, and the metabolic dysregulation and cytokine levels identified at the host cellular level support the development of novel medical treatment strategies.

scholarly journals Alternative Sigma Factor RpoX Is a Part of the RpoE Regulon and Plays Distinct Roles in Stress Responses, Motility, Biofilm Formation, and Hemolytic Activities in the Marine Pathogen Vibrio alginolyticus

2019 ◽  
Vol 85 (14) ◽  
Author(s):  
Dan Gu ◽  
Jun Zhang ◽  
Yuan Hao ◽  
Rongjing Xu ◽  
Yuanxing Zhang ◽  
...  
Keyword(s):  
High Temperature ◽  
Osmotic Stress ◽  
Stress Responses ◽  
Sigma Factor ◽  
Biofilm Formation ◽  
Vibrio Alginolyticus ◽  
Alternative Sigma Factor ◽  
Rna Seq ◽  
Content Type ◽  
Regulatory Cascades

ABSTRACT Vibrio alginolyticus is one of the most abundant microorganisms in marine environments and is also an opportunistic pathogen mediating high-mortality vibriosis in marine animals. Alternative sigma factors play essential roles in bacterial pathogens in the adaptation to environmental changes during infection and the adaptation to various niches, but little is known about them for V. alginolyticus. Our previous investigation indicated that the transcript level of the gene rpoX significantly decreased in an RpoE mutant. Here, we found that rpoX was highly expressed in response to high temperature and low osmotic stress and was under the direct control of the alternative sigma factor RpoE and its own product RpoX. Moreover, transcriptome sequencing (RNA-seq) results showed that RpoE and RpoX had different regulons, although they coregulated 105 genes at high temperature (42°C), including genes associated with biofilm formation, motility, virulence, regulatory factors, and the stress response. RNA-seq and chromatin immunoprecipitation sequencing (ChIP-seq) analyses as well as electrophoretic mobility shift assays (EMSAs) revealed the distinct binding motifs of RpoE and RpoX proteins. Furthermore, quantitative real-time reverse transcription-PCR (qRT-PCR) analysis also confirmed that RpoX can upregulate genes associated with flagella, biofilm formation, and hemolytic activities at higher temperatures. rpoX abrogation does not appear to attenuate virulence toward model fish at normal temperature. Collectively, data from this study demonstrated the regulatory cascades of RpoE and an alternative sigma factor, RpoX, in response to heat and osmotic stresses and their distinct and overlapping roles in pathogenesis and stress responses in the marine bacterium V. alginolyticus. IMPORTANCE The alternative sigma factor RpoE is essential for the virulence of Vibrio alginolyticus toward marine fish, coral, and other animals in response to sea surface temperature increases. In this study, we characterized another alternative sigma factor, RpoX, which is induced at high temperatures and under low-osmotic-stress conditions. The expression of rpoX is under the tight control of RpoE and RpoX. Although RpoE and RpoX coregulate 105 genes, they are programming different regulatory functions in stress responses and virulence in V. alginolyticus. These findings illuminated the RpoE-RpoX-centered regulatory cascades and their distinct and overlapping regulatory roles in V. alginolyticus, which facilitates unraveling of the mechanisms by which the bacterium causes diseases in various sea animals in response to temperature fluctuations as well as the development of appropriate strategies to tackle infections by this bacterium.

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