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 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.

Activation of the alternative sigma factor SigB of Staphylococcus aureus following internalization by epithelial cells – An in vivo proteomics perspective

2014 ◽  
Vol 304 (2) ◽  
pp. 177-187 ◽  
Author(s):  
Henrike Pförtner ◽  
Marc S. Burian ◽  
Stephan Michalik ◽  
Maren Depke ◽  
Petra Hildebrandt ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Epithelial Cells ◽  
Sigma Factor ◽  
Alternative Sigma Factor

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 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.

scholarly journals Alternate Sigma Factor RpoS Is Required for the In Vivo-Specific Repression of Borrelia burgdorferi Plasmid lp54-Borne ospA and lp6.6 Genes

2005 ◽  
Vol 187 (22) ◽  
pp. 7845-7852 ◽  
Author(s):  
Melissa J. Caimano ◽  
Christian H. Eggers ◽  
Cynthia A. Gonzalez ◽  
Justin D. Radolf
Keyword(s):  
Borrelia Burgdorferi ◽  
Sigma Factor ◽  
Mammalian Host ◽  
Alternative Sigma Factor ◽  
Tick Feeding ◽  
Accessory Factor ◽  
Repressor Molecule ◽  
Specific Virulence ◽  
Sigma Factor Rpos

ABSTRACT While numerous positively regulated loci have been characterized during the enzootic cycle of Borrelia burgdorferi, very little is known about the mechanism(s) involved in the repression of borrelial loci either during tick feeding or within the mammalian host. Here, we report that the alternative sigma factor RpoS is required for the in vivo-specific repression of at least two RpoD-dependent B. burgdorferi loci, ospA and lp6.6. The downregulation of ospA and Ip6.6 appears to require either a repressor molecule whose expression is RpoS dependent or an accessory factor which enables RpoS to directly interact with the ospA and Ip6.6 promoter elements, thereby blocking transcription by RpoD. The central role for RpoS during the earliest stages of host adaptation suggests that tick feeding imparts signals to spirochetes that trigger the RpoS-dependent repression, as well as expression, of in vivo-specific virulence factors critical for the tick-to-mammalian host transition.

scholarly journals Antibacterial Activity of a Competence-Stimulating Peptide in Experimental Sepsis Caused by Streptococcus pneumoniae

2004 ◽  
Vol 48 (12) ◽  
pp. 4725-4732 ◽  
Author(s):  
Marco R. Oggioni ◽  
Francesco Iannelli ◽  
Susanna Ricci ◽  
Damiana Chiavolini ◽  
Riccardo Parigi ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Histidine Kinase ◽  
Drug Target ◽  
Systemic Disease ◽  
Experimental Sepsis ◽  
Inhibition Of Growth ◽  
Peptide Pheromone ◽  
Set Up

ABSTRACT Streptococcus pneumoniae, a major cause of human disease, produces a 17-mer autoinducer peptide pheromone (competence-stimulating peptide [CSP]) for the control of competence for genetic transformation. Due to previous work linking CSP to stress phenotypes, we set up an in vivo sepsis model to assay its effect on virulence. Our data demonstrate a significant increase in the rates of survival of mice, reductions of blood S. pneumoniae counts, and prolonged times to death for mice treated with CSP. In vitro the dose of CSP used in the animal model produced a transitory inhibition of growth. When a mutant with a mutation in the CSP sensor histidine kinase was assayed, no bacteriostatic phenotype was detected in vitro and no change in disease outcome was observed in vivo. The data demonstrate that CSP, which induces in vitro a temporary growth arrest through stimulation of its cognate histidine kinase receptor, is able to block systemic disease in mice. This therapeutic effect is novel, in that the drug-like effect is obtained by stimulation, rather than inhibition, of a bacterial drug target.

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