scholarly journals Identification of the Gene Encoding the Alternative Sigma Factor ςB from Listeria monocytogenesand Its Role in Osmotolerance

1998 ◽  
Vol 180 (17) ◽  
pp. 4547-4554 ◽  
Author(s):  
Lynne A. Becker ◽  
Mehmet Sevket Çetin ◽  
Robert W. Hutkins ◽  
Andrew K. Benson
Keyword(s):  
Sigma Factor ◽  
Low Temperatures ◽  
Low Ph ◽  
Alternative Sigma Factor ◽  
Null Mutation ◽  
Gene Encoding ◽  
Related Bacterium ◽  
Physical Organization ◽  
Physical And Chemical ◽  
Insight Into

ABSTRACT Listeria monocytogenes is well known for its robust physiology, which permits growth at low temperatures under conditions of high osmolarity and low pH. Although studies have provided insight into the mechanisms used by L. monocytogenes to allay the physiological consequences of these adverse environments, little is known about how these responses are coordinated. In the studies presented here, we have cloned the sigB gene and severalrsb genes from L. monocytogenes, encoding homologs of the alternative sigma factor ςB and the RsbUVWX proteins, which govern transcription of a general stress regulon in the related bacterium Bacillus subtilis. TheL. monocytogenes and B. subtilis sigB andrsb genes are similar in sequence and physical organization; however, we observed that the activity of ςB in L. monocytogenes was uniquely responsive to osmotic upshifting, temperature downshifting, and the presence of EDTA in the growth medium. The magnitude of the response was greatest after an osmotic upshift, suggesting a role for ςB in coordinating osmotic responses in L. monocytogenes. A null mutation in the sigB gene led to substantial defects in the ability of L. monocytogenesto use betaine and carnitine as osmoprotectants. Subsequent measurements of betaine transport confirmed that the absence of ςB reduced the ability of the cells to accumulate betaine. Thus, ςB coordinates responses to a variety of physical and chemical signals, and its function facilitates the growth of L. monocytogenes under conditions of high osmotic strength.

Exotoxin A production in Pseudomonas aeruginosa requires the iron‐regulated pvdS gene encoding an alternative sigma factor

1996 ◽  
Vol 21 (5) ◽  
pp. 1019-1028 ◽  
Author(s):  
Urs A. Ochsner ◽  
Zaiga Johnson ◽  
Iain L. Lamont ◽  
Heather E. Cunliffe ◽  
Michael L. Vasil
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Sigma Factor ◽  
Alternative Sigma Factor ◽  
Exotoxin A ◽  
Gene Encoding

scholarly journals Ensifer aridi LMR001T Symbiosis and Tolerance to Stress Do Not Require the Alternative Sigma Factor RpoE2

Agronomy ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1787
Author(s):  
Meryem Belfquih ◽  
Ilham Sakrouhi ◽  
Hassan Ait-Benhassou ◽  
Emeric Dubois ◽  
Dany Severac ◽  
...  
Keyword(s):  
Stress Response ◽  
Sigma Factor ◽  
A Priori ◽  
Climatic Conditions ◽  
Targeted Mutagenesis ◽  
Alternative Sigma Factor ◽  
Gene Encoding ◽  
General Stress Response ◽  
Stress Genes ◽  
General Stress

The recently proposed species Ensifer aridi represents an interesting model to study adaptive mechanisms explaining its maintenance under stressful pedo-climatic conditions. To get insights into functions associated with hyperosmotic stress adaptation in E. aridi, we first performed RNAseq profiling of cells grown under sub-lethal stresses applied by permeating (NaCl) and non-permeating (PEG8000) solutes that were compared to a transcriptome from unstressed bacteria. Then an a priori approach, consisting of targeted mutagenesis of the gene encoding alternative sigma factor (rpoE2), involved in the General Stress Response combined with phenotyping and promoter gfp fusion-based reporter assays of selected genes was carried out to examine the involvement of rpoE2 in symbiosis and stress response. The majority of motility and chemotaxis genes were repressed by both stresses. Results also suggest accumulation of compatible solute trehalose under stress and other metabolisms such as inositol catabolism or the methionine cycling-generating S-adenosyl methionine appears strongly induced notably under salt stress. Interestingly, many functions regulated by salt were shown to favor competitiveness for nodulation in other rhizobia, supporting a role of stress genes for proper symbiosis’ development and functioning. However, despite activation of the general stress response and identification of several genes possibly under its control, our data suggest that rpoE2 was not essential for stress tolerance and symbiosis’ development, indicating that E. aridi possesses alternative regulatory mechanisms to adapt and respond to stressful environments.

scholarly journals Competence for Genetic Transformation in Streptococcus pneumoniae: Termination of Activity of the Alternative Sigma Factor ComX Is Independent of Proteolysis of ComX and ComW

2009 ◽  
Vol 191 (10) ◽  
pp. 3359-3366 ◽  
Author(s):  
Andrew Piotrowski ◽  
Ping Luo ◽  
Donald A. Morrison
Keyword(s):  
Streptococcus Pneumoniae ◽  
Genetic Transformation ◽  
Sigma Factor ◽  
Transcriptional Activity ◽  
Physiological State ◽  
Alternative Sigma Factor ◽  
Rapid Loss ◽  
Gene Encoding ◽  
Peptide Pheromone

ABSTRACT Competence for genetic transformation in Streptococcus pneumoniae is a transient physiological state whose development is coordinated by a peptide pheromone (CSP) and its receptor, which activates transcription of two downstream genes, comX and comW, and 15 other “early” genes. ComX, a transient alternative sigma factor, drives transcription of “late” genes, many of which are essential for transformation. In vivo, ComW both stabilizes ComX against proteolysis by the ClpE-ClpP protease and stimulates its activity. Interestingly, stabilization of ComX by deletion of the gene encoding the ClpP protease did not extend the period of competence. We considered the hypothesis that the rapid decay of competence arises from a rapid loss of ComW and thus of its ComX stimulating activity, so that ComX might persist but lose its transcriptional activity. Western analysis revealed that ComW is indeed a transient protein, which is also stabilized by deletion of the gene encoding the ClpP protease. However, stabilizing both ComX and ComW did not prolong either ComX activity or the period of transformation, indicating that termination of the transcriptional activity of ComX is not dependent on proteolysis of ComW.

scholarly journals Identification and Characterization of theErwinia amylovora rpoS Gene: RpoS Is Not Involved in Induction of Fireblight Disease Symptoms

1998 ◽  
Vol 180 (24) ◽  
pp. 6789-6792 ◽  
Author(s):  
M. Anderson ◽  
C. E. Pollitt ◽  
I. S. Roberts ◽  
J. A. Eastgate
Keyword(s):  
Sigma Factor ◽  
Erwinia Amylovora ◽  
Environmental Stresses ◽  
Alternative Sigma Factor ◽  
Gene Encoding ◽  
Disease Symptoms ◽  
Highly Sensitive ◽  
Identification And Characterization ◽  
Sigma Factor Rpos

ABSTRACT The Erwinia amylovora rpoS gene, encoding the alternative sigma factor RpoS, has been cloned and characterized. Though highly sensitive to a number of environmental stresses, anE. amylovora rpoS mutant was not compromised in its ability to grow or cause disease symptoms within apple seedlings or in an overwintering model.

The formation of cyclopropane fatty acids in Salmonella enterica serovar Typhimurium

Microbiology ◽  
2005 ◽  
Vol 151 (1) ◽  
pp. 209-218 ◽  
Author(s):  
Bae Hoon Kim ◽  
Seungki Kim ◽  
Hyeon Guk Kim ◽  
Jin Lee ◽  
In Soo Lee ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Stationary Phase ◽  
Sigma Factor ◽  
Salmonella Enterica ◽  
Unsaturated Fatty Acids ◽  
Low Ph ◽  
Cyclopropane Fatty Acid ◽  
Alternative Sigma Factor ◽  
Serovar Typhimurium ◽  
Sigma Factor Rpos

The formation of cyclopropane fatty acid (CFA) and its role in the acid shock response in Salmonella enterica serovar Typhimurium (S. typhimurium) was investigated. Data obtained by GC/MS demonstrated that the CFA level in S. typhimurium increased upon its entry to the stationary phase, as in other bacteria. The cfa gene encoding CFA synthase was cloned, and mutants of the cfa gene were constructed by allelic exchange. A cfa mutant could not produce CFA and was sensitive to low pH. Introduction of a functional cfa gene into a cfa mutant cell made the mutant convert all unsaturated fatty acids to CFAs and partially restored resistance to low pH. Interestingly, the alternative sigma factor RpoS, which was induced during the stationary phase, affected the production of C19 CFA but not C17 CFA. Western blotting analysis showed that the increase in expression of CFA synthase at early stationary phase was due to the alternative sigma factor RpoS.

scholarly journals Ecf, an Alternative Sigma Factor from Neisseria gonorrhoeae, Controls Expression of msrAB, Which Encodes Methionine Sulfoxide Reductase

2006 ◽  
Vol 188 (10) ◽  
pp. 3463-3469 ◽  
Author(s):  
Ishara C. Gunesekere ◽  
Charlene M. Kahler ◽  
Catherine S. Ryan ◽  
Lori A. S. Snyder ◽  
Nigel J. Saunders ◽  
...  
Keyword(s):  
Neisseria Gonorrhoeae ◽  
Sigma Factor ◽  
Reductase Activity ◽  
Methionine Sulfoxide ◽  
Methionine Sulfoxide Reductase ◽  
Transcriptional Unit ◽  
Alternative Sigma Factor ◽  
Gene Encoding ◽  
Strain Fa1090

ABSTRACT A DNA microarray was used to identify genes transcribed in Neisseria gonorrhoeae using Ecf, an alternative sigma factor. No differences between the transcriptional profiles of strain FA1090 and a mutant where ecf had been inactivated could be detected when both were grown in vitro. We therefore constructed a gonococcal strain in which Ecf can be overexpressed. Some differentially expressed genes are clustered with ecf on the genome and appear to form a single transcriptional unit. Expression of the gene encoding MsrAB, which possesses methionine sulfoxide reductase activity, was also dependent on Ecf, suggesting that the regulon responds to oxidative damage. Western blotting confirmed that the increased level of MsrAB protein is dependent on the presence of Ecf.

Antibacterial and Anti-Biofilm Biosynthesised Silver and Gold Nanoparticles for Medical Applications: Mechanism of Action, Toxicity and Current Status

2020 ◽  
Vol 17 (2) ◽  
pp. 88-100 ◽  
Author(s):  
Sundos Suleman Ismail Abdalla ◽  
Haliza Katas ◽  
Fazren Azmi ◽  
Mohd Fauzi Mh Busra
Keyword(s):  
Gold Nanoparticles ◽  
Synthesis Method ◽  
Chemical Characterization ◽  
Current Status ◽  
Silver And Gold Nanoparticles ◽  
Physical And Chemical Characterization ◽  
Biosynthesized Agnps ◽  
Physical And Chemical ◽  
Insight Into ◽  
Bio Synthesis

Fast progress in nanoscience and nanotechnology has contributed to the way in which people diagnose, combat, and overcome various diseases differently from the conventional methods. Metal nanoparticles, mainly silver and gold nanoparticles (AgNPs and AuNPs, respectively), are currently developed for many applications in the medical and pharmaceutical area including as antibacterial, antibiofilm as well as anti-leshmanial agents, drug delivery systems, diagnostics tools, as well as being included in personal care products and cosmetics. In this review, the preparation of AgNPs and AuNPs using different methods is discussed, particularly the green or bio- synthesis method as well as common methods used for their physical and chemical characterization. In addition, the mechanisms of the antimicrobial and anti-biofilm activity of AgNPs and AuNPs are discussed, along with the toxicity of both nanoparticles. The review will provide insight into the potential of biosynthesized AgNPs and AuNPs as antimicrobial nanomaterial agents for future use.

scholarly journals Global transcriptional response to vancomycin in Mycobacterium tuberculosis

Microbiology ◽  
2009 ◽  
Vol 155 (4) ◽  
pp. 1093-1102 ◽  
Author(s):  
Roberta Provvedi ◽  
Francesca Boldrin ◽  
Francesco Falciani ◽  
Giorgio Palù ◽  
Riccardo Manganelli
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Surface Stress ◽  
Sigma Factor ◽  
Clustering Analysis ◽  
Transcriptional Response ◽  
Alternative Sigma Factor ◽  
Hierarchical Clustering Analysis ◽  
Physiological Mechanisms ◽  
Basal Resistance ◽  
Antibacterial Drugs

In order to gain additional understanding of the physiological mechanisms used by bacteria to maintain surface homeostasis and to identify potential targets for new antibacterial drugs, we analysed the variation of the Mycobacterium tuberculosis transcriptional profile in response to inhibitory and subinhibitory concentrations of vancomycin. Our analysis identified 153 genes differentially regulated after exposing bacteria to a concentration of the drug ten times higher than the MIC, and 141 genes differentially expressed when bacteria were growing in a concentration of the drug eightfold lower than the MIC. Hierarchical clustering analysis indicated that the response to these different conditions is different, although with some overlap. This approach allowed us to identify several genes whose products could be involved in the protection from antibiotic stress targeting the envelope and help to confer the basal level of M. tuberculosis resistance to antibacterial drugs, such as Rv2623 (UspA-like), Rv0116c, PE20-PPE31, PspA and proteins related to toxin–antitoxin systems. Moreover, we also demonstrated that the alternative sigma factor σ E confers basal resistance to vancomycin, once again underlining its importance in the physiology of the mycobacterial surface stress response.

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