Alternative Sigma Factor SigK Has a Role in Stress Tolerance of Group I Clostridium botulinum Strain ATCC 3502

ABSTRACTThe role of the alternative sigma factor SigK in cold and osmotic stress tolerance ofClostridium botulinumATCC 3502 was demonstrated by induction ofsigKafter temperature downshift and exposure to hyperosmotic conditions and by impaired growth of thesigKmutants under the respective conditions.

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Evaluation of normalization reference genes for RT-qPCR analysis of spo0A and four sporulation sigma factor genes in Clostridium botulinum Group I strain ATCC 3502

Anaerobe ◽

10.1016/j.anaerobe.2013.12.003 ◽

2014 ◽

Vol 26 ◽

pp. 14-19 ◽

Cited By ~ 15

Author(s):

David G. Kirk ◽

Eveliina Palonen ◽

Hannu Korkeala ◽

Miia Lindström

Keyword(s):

Sigma Factor ◽

Reference Genes ◽

Clostridium Botulinum ◽

Strain Atcc ◽

Qpcr Analysis ◽

Group I

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The Alternative Sigma Factor SigB Is Required for the Pathogenicity of Bacillus thuringiensis

Journal of Bacteriology ◽

10.1128/jb.00265-20 ◽

2020 ◽

Vol 202 (21) ◽

Author(s):

Stéphanie Henry ◽

Didier Lereclus ◽

Leyla Slamti

Keyword(s):

Life Cycle ◽

Stress Response ◽

Bacillus Thuringiensis ◽

Sigma Factor ◽

Oral Route ◽

Alternative Sigma Factor ◽

Gram Positive ◽

Content Type ◽

General Stress Response

ABSTRACT To adapt to changing and potentially hostile environments, bacteria can activate the transcription of genes under the control of alternative sigma factors, such as SigB, a master regulator of the general stress response in several Gram-positive species. Bacillus thuringiensis is a Gram-positive spore-forming invertebrate pathogen whose life cycle includes a variety of environments, including plants and the insect hemocoel or gut. Here, we assessed the role of SigB during the infectious cycle of B. thuringiensis in a Galleria mellonella insect model. We used a fluorescent reporter coupled to flow cytometry and showed that SigB was activated in vivo. We also showed that the pathogenicity of the ΔsigB mutant was severely affected when inoculated via the oral route, suggesting that SigB is critical for B. thuringiensis adaptation to the gut environment of the insect. We could not detect an effect of the sigB deletion on the survival of the bacteria or on their sporulation efficiency in the cadavers. However, the gene encoding the pleiotropic regulator Spo0A was upregulated in the ΔsigB mutant cells during the infectious process. IMPORTANCE Pathogenic bacteria often need to transition between different ecosystems, and their ability to cope with such variations is critical for their survival. Several Gram-positive species have developed an adaptive response mediated by the general stress response alternative sigma factor SigB. In order to understand the ecophysiological role of this regulator in Bacillus thuringiensis, an entomopathogenic bacterium widely used as a biopesticide, we sought to examine the fate of a ΔsigB mutant during its life cycle in the natural setting of an insect larva. This allowed us, in particular, to show that SigB was activated during infection and that it was required for the pathogenicity of B. thuringiensis via the oral route of infection.

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Mycobacterial SigA and SigB Cotranscribe Essential Housekeeping Genes during Exponential Growth

mBio ◽

10.1128/mbio.00273-19 ◽

2019 ◽

Vol 10 (3) ◽

Cited By ~ 4

Author(s):

Kelley Hurst-Hess ◽

Rajesh Biswas ◽

Yong Yang ◽

Paulami Rudra ◽

Erica Lasek-Nesselquist ◽

...

Keyword(s):

Stationary Phase ◽

Exponential Growth ◽

Sigma Factor ◽

Housekeeping Genes ◽

Sigma Factors ◽

Rrna Gene ◽

Content Type ◽

Group I ◽

Group Ii

ABSTRACTMycobacterial σBbelongs to the group II family of sigma factors, which are widely considered to transcribe genes required for stationary-phase survival and the response to stress. Here we explored the mechanism underlying the observed hypersensitivity of ΔsigBdeletion mutants ofMycobacteriumsmegmatis,M. abscessus, andM. tuberculosisto rifampin (RIF) and uncovered an additional constitutive role of σBduring exponential growth of mycobacteria that complements the function of the primary sigma factor, σA. Using chromatin immunoprecipitation sequencing (ChIP-Seq), we show that during exponential phase, σBbinds to over 200 promoter regions, including those driving expression of essential housekeeping genes, like the rRNA gene. ChIP-Seq of ectopically expressed σA-FLAG demonstrated that at least 61 promoter sites are recognized by both σAand σB. These results together suggest that RNA polymerase holoenzymes containing either σAor σBtranscribe housekeeping genes in exponentially growing mycobacteria. The RIF sensitivity of the ΔsigBmutant possibly reflects a decrease in the effective housekeeping holoenzyme pool, which results in susceptibility of the mutant to lower doses of RIF. Consistent with this model, overexpression of σArestores the RIF tolerance of the ΔsigBmutant to that of the wild type, concomitantly ruling out a specialized role of σBin RIF tolerance. Although the properties of mycobacterial σBparallel those ofEscherichiacoliσ38in its ability to transcribe a subset of housekeeping genes, σBpresents a clear departure from theE. coliparadigm, wherein the cellular levels of σ38are tightly controlled during exponential growth, such that the transcription of housekeeping genes is initiated exclusively by a holoenzyme containing σ70(E.σ70).IMPORTANCEAll mycobacteria encode a group II sigma factor, σB, closely related to the group I principal housekeeping sigma factor, σA. Group II sigma factors are widely believed to play specialized roles in the general stress response and stationary-phase transition in the bacteria that encode them. Contrary to this widely accepted view, we show an additional housekeeping function of σBthat complements the function of σAin logarithmically growing cells. These findings implicate a novel and dynamic partnership between σAand σBin maintaining the expression of housekeeping genes in mycobacteria and can perhaps be extended to other bacterial species that possess multiple group II sigma factors.

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Salt-Induced Stress Stimulates a Lipoteichoic Acid-Specific Three-Component Glycosylation System inStaphylococcus aureus

Journal of Bacteriology ◽

10.1128/jb.00017-18 ◽

2018 ◽

Vol 200 (12) ◽

Cited By ~ 15

Author(s):

Kelvin Kho ◽

Timothy C. Meredith

Keyword(s):

Staphylococcus Aureus ◽

Sigma Factor ◽

Cell Envelope ◽

Normal Growth ◽

Lipoteichoic Acid ◽

Growth Conditions ◽

Growth Media ◽

Alternative Sigma Factor ◽

Content Type

ABSTRACTLipoteichoic acid (LTA) inStaphylococcus aureusis a poly-glycerophosphate polymer anchored to the outer surface of the cell membrane. LTA has numerous roles in cell envelope physiology, including regulating cell autolysis, coordinating cell division, and adapting to environmental growth conditions. LTA is often further modified with substituents, includingd-alanine and glycosyl groups, to alter cellular function. While the genetic determinants ofd-alanylation have been largely defined, the route of LTA glycosylation and its role in cell envelope physiology have remained unknown, in part due to the low levels of basal LTA glycosylation inS. aureus. We demonstrate here thatS. aureusutilizes a membrane-associated three-component glycosylation system composed of an undecaprenol (Und)N-acetylglucosamine (GlcNAc) charging enzyme (CsbB; SAOUHSC_00713), a putative flippase to transport loaded substrate to the outside surface of the cell (GtcA; SAOUHSC_02722), and finally an LTA-specific glycosyltransferase that adds α-GlcNAc moieties to LTA (YfhO; SAOUHSC_01213). We demonstrate that this system is specific for LTA with no cross recognition of the structurally similar polyribitol phosphate containing wall teichoic acids. We show that while wild-typeS. aureusLTA has only a trace of GlcNAcylated LTA under normal growth conditions, amounts are raised upon either overexpressing CsbB, reducing endogenousd-alanylation activity, expressing the cell envelope stress responsive alternative sigma factor SigB, or by exposure to environmental stress-inducing culture conditions, including growth media containing high levels of sodium chloride.IMPORTANCEThe role of glycosylation in the structure and function ofStaphylococcus aureuslipoteichoic acid (LTA) is largely unknown. By defining key components of the LTA three-component glycosylation pathway and uncovering stress-induced regulation by the alternative sigma factor SigB, the role ofN-acetylglucosamine tailoring during adaptation to environmental stresses can now be elucidated. As thedltand glycosylation pathways compete for the same sites on LTA and induction of glycosylation results in decreasedd-alanylation, the interplay between the two modification systems holds implications for resistance to antibiotics and antimicrobial peptides.

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Involvement of Two-Component System CBO0366/CBO0365 in the Cold Shock Response and Growth of Group I (Proteolytic) Clostridium botulinum ATCC 3502 at Low Temperatures

Applied and Environmental Microbiology ◽

10.1128/aem.00555-12 ◽

2012 ◽

Vol 78 (15) ◽

pp. 5466-5470 ◽

Cited By ~ 19

Author(s):

Miia Lindström ◽

Elias Dahlsten ◽

Henna Söderholm ◽

Katja Selby ◽

Panu Somervuo ◽

...

Keyword(s):

Clostridium Botulinum ◽

Cold Shock ◽

Two Component System ◽

Component System ◽

Content Type ◽

Cold Shock Response ◽

Group I ◽

Two Component ◽

Shock Response

ABSTRACTThe role of the two-component system (TCS) CBO0366/CBO0365 in the cold shock response and growth of the mesophilicClostridium botulinumATCC 3502 at 15°C was demonstrated by induced expression of the TCS genes upon cold shock and impaired growth of the TCS mutants at 15°C.

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Whole-Genome Single-Nucleotide-Polymorphism Analysis for Discrimination of Clostridium botulinum Group I Strains

Applied and Environmental Microbiology ◽

10.1128/aem.03934-13 ◽

2014 ◽

Vol 80 (7) ◽

pp. 2125-2132 ◽

Cited By ~ 23

Author(s):

Narjol Gonzalez-Escalona ◽

Ruth Timme ◽

Brian H. Raphael ◽

Donald Zink ◽

Shashi K. Sharma

Keyword(s):

Single Nucleotide Polymorphism ◽

Clostridium Botulinum ◽

Toxin Gene ◽

Polymorphism Analysis ◽

Snp Analysis ◽

Whole Genome ◽

Nucleotide Polymorphism ◽

Single Nucleotide ◽

Content Type ◽

Group I

ABSTRACTClostridium botulinumis a genetically diverse Gram-positive bacterium producing extremely potent neurotoxins (botulinum neurotoxins A through G [BoNT/A-G]). The complete genome sequences of three strains harboring only the BoNT/A1 nucleotide sequence are publicly available. Although these strains contain a toxin cluster (HA+OrfX−) associated with hemagglutinin genes, little is known about the genomes of subtype A1 strains (termed HA−OrfX+) that lack hemagglutinin genes in the toxin gene cluster. We sequenced the genomes of three BoNT/A1-producingC. botulinumstrains: two strains with the HA+OrfX−cluster (69A and 32A) and one strain with the HA−OrfX+cluster (CDC297). Whole-genome phylogenic single-nucleotide-polymorphism (SNP) analysis of these strains along with other publicly availableC. botulinumgroup I strains revealed five distinct lineages. Strains 69A and 32A clustered with theC. botulinumtype A1 Hall group, and strain CDC297 clustered with theC. botulinumtype Ba4 strain 657. This study reports the use of whole-genome SNP sequence analysis for discrimination ofC. botulinumgroup I strains and demonstrates the utility of this analysis in quickly differentiatingC. botulinumstrains harboring identical toxin gene subtypes. This analysis further supports previous work showing that strains CDC297 and 657 likely evolved from a common ancestor and independently acquired separate BoNT/A1 toxin gene clusters at distinct genomic locations.

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Role of a novel pathogen-induced pepper C3–H–C4 type RING-finger protein gene, CaRFP1, in disease susceptibility and osmotic stress tolerance

Plant Molecular Biology ◽

10.1007/s11103-006-9110-2 ◽

2006 ◽

Vol 63 (4) ◽

pp. 571-588 ◽

Cited By ~ 41

Author(s):

Jeum Kyu Hong ◽

Hyong Woo Choi ◽

In Sun Hwang ◽

Byung Kook Hwang

Keyword(s):

Osmotic Stress ◽

Stress Tolerance ◽

Disease Susceptibility ◽

Protein Gene ◽

Ring Finger ◽

Ring Finger Protein ◽

Osmotic Stress Tolerance ◽

Finger Protein

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Listeria monocytogenes σHContributes to Expression of Competence Genes and Intracellular Growth

Journal of Bacteriology ◽

10.1128/jb.00718-15 ◽

2016 ◽

Vol 198 (8) ◽

pp. 1207-1217 ◽

Cited By ~ 4

Author(s):

Veronica Medrano Romero ◽

Kazuya Morikawa

Keyword(s):

Transcription Factor ◽

Listeria Monocytogenes ◽

Sigma Factor ◽

Physiological Role ◽

Population Level ◽

Alternative Sigma Factor ◽

Intracellular Growth ◽

Content Type ◽

Gram Positive Bacteria ◽

Regulation Scheme

ABSTRACTThe alternative sigma factor σHhas two functions in Gram-positive bacteria: it regulates sporulation and the development of genetic competence.Listeria monocytogenesis a nonsporulating species in which competence has not yet been detected. Nevertheless, the main competence regulators and a series of orthologous genes that form the competence machinery are present in its genome; some of the competence genes play a role in optimal phagosomal escape. In this study, strains overexpressing σHand strains with a σHdeletion were used to elucidate the contribution of σHto the expression of the competence machinery genes inL. monocytogenes. Gene expression analysis showed that σHis, indeed, involved incomGandcomEregulation. Unexpectedly, we observed a unique regulation scheme in which σHand the transcription factor ComK were involved. Population-level analysis showed that even with the overexpression of both factors, only a fraction of the cells expressed the competence machinery genes. Although we could not detect competence, σHwas crucial for phagosomal escape, which implies that this alternative sigma factor has specifically evolved to regulate theL. monocytogenesintracellular life cycle.IMPORTANCEListeria monocytogenescan be an intracellular pathogen capable of causing serious infections in humans and animal species. Recently, the competence machinery genes were described as being necessary for optimal phagosomal escape, in which the transcription factor ComK plays an important role. On the other hand, our previous phylogenetic analysis suggested that the alternative sigma factor σHmight play a role in the regulation of competence genes. The present study shows that some of the competence genes belong to the σHregulon and, importantly, that σHis essential for intracellular growth, implying a unique physiological role of σHamongFirmicutes.

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