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

scholarly journals Differential Abilities of Capsulated and Noncapsulated Staphylococcus aureus Isolates from Diverse agr Groups To Invade Mammary Epithelial Cells

2006 ◽  
Vol 75 (2) ◽  
pp. 886-891 ◽  
Author(s):  
Fernanda R. Buzzola ◽  
Lucía P. Alvarez ◽  
Lorena P. N. Tuchscherr ◽  
María S. Barbagelata ◽  
Santiago M. Lattar ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Mammary Gland ◽  
Epithelial Cells ◽  
Pcr Amplification ◽  
Variable Region ◽  
Polymorphism Analysis ◽  
Accessory Gene ◽  
Group I ◽  
Group Ii

ABSTRACT Staphylococcus aureus is the bacterium most frequently isolated from milk of bovines with mastitis. Four allelic groups, which interfere with the regulatory activities among the different groups, have been identified in the accessory gene regulator (agr) system. The aim of this study was to ascertain the prevalence of the different agr groups in capsulated and noncapsulated S. aureus bacteria isolated from mastitic bovines in Argentina and whether a given agr group was associated with MAC-T cell invasion and in vivo persistence. Eighty-eight percent of the bovine S. aureus strains were classified in agr group I. The remainder belonged in agr groups II, III, and IV (2, 8, and 2%, respectively). By restriction fragment length polymorphism analysis after PCR amplification of the agr locus variable region, six agr restriction types were identified. All agr group I strains presented a unique allele (A/1), whereas strains from groups II, III, and IV exhibited more diversity. Bovine S. aureus strains defined as being in agr group I (capsulated or noncapsulated) showed significantly increased abilities to be internalized within MAC-T cells, compared with isolates from agr groups II, III, and IV. agr group II or IV S. aureus strains were cleared more efficiently than agr group I strains from the murine mammary gland. The results suggest that agr group I S. aureus strains are more efficiently internalized within epithelial cells and can persist in higher numbers in mammary gland tissue than S. aureus strains classified in agr group II, III, or IV.

scholarly journals CspA Regulates Pigment Production in Staphylococcus aureus through a SigB-Dependent Mechanism

2005 ◽  
Vol 187 (23) ◽  
pp. 8181-8184 ◽  
Author(s):  
Samuel Katzif ◽  
Eun-Hee Lee ◽  
Anthony B. Law ◽  
Yih-Ling Tzeng ◽  
William M. Shafer
Keyword(s):  
Staphylococcus Aureus ◽  
Sigma Factor ◽  
Cold Shock ◽  
Pigment Production ◽  
Cold Shock Protein ◽  
Alternative Sigma Factor ◽  
Expression Of Genes ◽  
Maximal Production ◽  
Dependent Mechanism

ABSTRACT We report that the cold shock protein CspA of Staphylococcus aureus is required for maximal production of pigment. Results from transcriptional studies revealed that loss of CspA resulted in decreased expression of genes needed for the biosynthesis of 4,4′-diaponeurosporene and the alternative sigma factor SigB.

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

2018 ◽  
Vol 200 (12) ◽  
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.

scholarly journals Role of RsbU in Controlling SigB Activity in Staphylococcus aureus following Alkaline Stress

2009 ◽  
Vol 191 (8) ◽  
pp. 2561-2573 ◽  
Author(s):  
Jan Pané-Farré ◽  
Beate Jonas ◽  
Steven W. Hardwick ◽  
Katrin Gronau ◽  
Richard J. Lewis ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
High Activity ◽  
Protein Phosphatase ◽  
Sigma Factor ◽  
Alternative Sigma Factor ◽  
Alkaline Stress ◽  
High Molecular Weight Complex ◽  
Terminal Domain ◽  
Related Organism

ABSTRACT SigB is an alternative sigma factor that controls a large regulon in Staphylococcus aureus. Activation of SigB requires RsbU, a protein phosphatase 2C (PP2C)-type phosphatase. In a closely related organism, Bacillus subtilis, RsbU activity is stimulated upon interaction with RsbT, a kinase, which following an activating stimulus switches from a 25S high-molecular-weight complex, the stressosome, to the N-terminal domain of RsbU. Active RsbU dephosporylates RsbV and thereby triggers the release of SigB from its inhibitory complex with RsbW. While RsbU, RsbV, RsbW, and SigB are conserved in S. aureus, proteins similar to RsbT and the components of the stressosome are not, raising the question of how RsbU activity and hence SigB activity are controlled in S. aureus. We found that in contrast to the case in B. subtilis, the induced expression of RsbU was sufficient to stimulate SigB-dependent transcription in S. aureus. However, activation of SigB-dependent transcription following alkaline stress did not lead to a clear accumulation of SigB and its regulators RsbV and RsbW or to a change in the RsbV/RsbV-P ratio in S. aureus. When expressed in B. subtilis, the S. aureus RsbU displayed a high activity even in the absence of an inducing stimulus. This high activity could be transferred to the PP2C domain of the B. subtilis RsbU protein by a fusion to the N-terminal domain of the S. aureus RsbU. Collectively, the data suggest that the activity of the S. aureus RsbU and hence SigB may be subjected to different regulation in comparison to that in B. subtilis.

scholarly journals Inhibition of Transcription in Staphylococcus aureus by a Primary Sigma Factor-Binding Polypeptide from Phage G1

2009 ◽  
Vol 191 (12) ◽  
pp. 3763-3771 ◽  
Author(s):  
Mohammed Dehbi ◽  
Gregory Moeck ◽  
Francis F. Arhin ◽  
Pascale Bauda ◽  
Dominique Bergeron ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Rna Polymerase ◽  
Sigma Factor ◽  
Exponential Growth Phase ◽  
E Coli ◽  
Growth Inhibitory ◽  
Σ Factor ◽  
Transcription In Vitro

ABSTRACT The primary sigma factor of Staphylococcus aureus, σSA, regulates the transcription of many genes, including several essential genes, in this bacterium via specific recognition of exponential growth phase promoters. In this study, we report the existence of a novel staphylococcal phage G1-derived growth inhibitory polypeptide, referred to as G1ORF67, that interacts with σSA both in vivo and in vitro and regulates its activity. Delineation of the minimal domain of σSA that is required for its interaction with G1ORF67 as amino acids 294 to 360 near the carboxy terminus suggests that the G1 phage-encoded anti-σ factor may occlude the −35 element recognition domain of σSA. As would be predicted by this hypothesis, the G1ORF67 polypeptide abolished both RNA polymerase core-dependent binding of σSA to DNA and σSA-dependent transcription in vitro. While G1ORF67 profoundly inhibits transcription when expressed in S. aureus cells in mode of action studies, our finding that G1ORF67 was unable to inhibit transcription when expressed in Escherichia coli concurs with its inability to inhibit transcription by the E. coli holoenzyme in vitro. These features demonstrate the selectivity of G1ORF67 for S. aureus RNA polymerase. We predict that G1ORF67 is one of the central polypeptides in the phage G1 strategy to appropriate host RNA polymerase and redirect it to phage reproduction.

scholarly journals Blocking the alternative sigma factor RpoN reduces virulence ofPseudomonas aeruginosaisolated from cystic fibrosis patients and increases antibiotic sensitivity in a laboratory strain

2018 ◽  
Author(s):  
MG Lloyd ◽  
JL Vossler ◽  
CT Nomura ◽  
JF Moffat
Keyword(s):  
Cystic Fibrosis ◽  
Sigma Factor ◽  
Antimicrobial Agents ◽  
Laboratory Strain ◽  
Infection Model ◽  
Alternative Sigma Factor ◽  
Beta Lactam ◽  
Cis Acting

AbstractMultidrug-resistant organisms (MDROs) are increasing in the health care setting, and there are few antimicrobial agents available to treat infections caused by these bacteria.Pseudomonas aeruginosais an opportunistic pathogen in burn patients and individuals with cystic fibrosis (CF), and a leading cause of nosocomial infections.P. aeruginosais inherently resistant to many antibiotics and can develop or acquire resistance to others, limiting options for treatment.P. aeruginosahas virulence factors that are regulated by sigma factors in response to the tissue microenvironment. The alternative sigma factor, RpoN (σ54), regulates many virulence genes and is linked to antibiotic resistance. Recently, we described a cis-acting peptide, RpoN*, which acts as a “molecular roadblock”, binding RpoN consensus promoters at the −24 site and blocking transcription. RpoN* reduces virulence ofP. aeruginosalaboratory strains bothin vitroandin vivo,but its effects in clinical isolates was not known. We investigated the effects of RpoN* on phenotypically variedP. aeruginosastrains isolated from cystic fibrosis patients. RpoN* expression reduced motility, biofilm formation, and pathogenesis in aP. aeruginosa – C. elegansinfection model. RpoN* expression increased susceptibility to several beta-lactam based antibiotics in the lab strainP. aeruginosaPA19660Xen5. Here, we show that using a cis-acting peptide to block RpoN consensus promoters has potential clinical implications in reducing virulence and enhancing the activity of antibiotics.

scholarly journals The Staphylococcus aureus Alternative Sigma Factor ςB Controls the Environmental Stress Response but Not Starvation Survival or Pathogenicity in a Mouse Abscess Model

1998 ◽  
Vol 180 (23) ◽  
pp. 6082-6089 ◽  
Author(s):  
Pan F. Chan ◽  
Simon J. Foster ◽  
Eileen Ingham ◽  
Mark O. Clements
Keyword(s):  
Staphylococcus Aureus ◽  
Stress Response ◽  
Environmental Stress ◽  
Sigma Factor ◽  
Osmotic Shock ◽  
Alternative Sigma Factor ◽  
Dependent Manner ◽  
Virulence Determinant ◽  
Starvation Survival

ABSTRACT The role of ςB, an alternative sigma factor ofStaphylococcus aureus, has been characterized in response to environmental stress, starvation-survival and recovery, and pathogenicity. ςB was mainly expressed during the stationary phase of growth and was repressed by 1 M sodium chloride. AsigB insertionally inactivated mutant was created. In stress resistance studies, ςB was shown to be involved in recovery from heat shock at 54°C and in acid and hydrogen peroxide resistance but not in resistance to ethanol or osmotic shock. Interestingly, S. aureus acquired increased acid resistance when preincubated at a sublethal pH 4 prior to exposure to a lethal pH 2. This acid-adaptive response resulting in tolerance was mediated viasigB. However, ςB was not vital for the starvation-survival or recovery mechanisms. ςB does not have a major role in the expression of the global regulator of virulence determinant biosynthesis, staphylococcal accessory regulator (sarA), the production of a number of representative virulence factors, and pathogenicity in a mouse subcutaneous abscess model. However, SarA upregulates sigB expression in a growth-phase-dependent manner. Thus, ςB expression is linked to the processes controlling virulence determinant production. The role of ςB as a major regulator of the stress response, but not of starvation-survival, is discussed.

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