scholarly journals Identification of the sigB Operon inStaphylococcus epidermidis: Construction and Characterization of a sigB Deletion Mutant

2001 ◽  
Vol 69 (12) ◽  
pp. 7933-7936 ◽  
Author(s):  
Stefanie Kies ◽  
Michael Otto ◽  
Cuong Vuong ◽  
Friedrich Götz
Keyword(s):  
Staphylococcus Epidermidis ◽  
Sigma Factor ◽  
Biofilm Formation ◽  
Deletion Mutant ◽  
Alternative Sigma Factor ◽  
Global Regulator ◽  
Profound Influence ◽  
Cytoplasmic Proteins

ABSTRACT The role of the alternative sigma factor ςB inStaphylococcus epidermidis was investigated by the construction, complementation, and characterization of asigB deletion mutant. Electrophoretic analyses confirmed a profound influence of ςB on the expression of exoproteins and cytoplasmic proteins. Detailed investigation revealed reduced lipase and enhanced protease activity in the ςB mutant. Furthermore, no significant influence of ςB on heterologous biofilm formation or on the activity of the global regulator agr was detected.

scholarly journals RsbU-Dependent Regulation of Staphylococcus epidermidis Biofilm Formation Is Mediated via the Alternative Sigma Factor σB by Repression of the Negative Regulator Gene icaR

2004 ◽  
Vol 72 (7) ◽  
pp. 3838-3848 ◽  
Author(s):  
Johannes K.-M. Knobloch ◽  
Sebastian Jäger ◽  
Matthias A. Horstkotte ◽  
Holger Rohde ◽  
Dietrich Mack
Keyword(s):  
Staphylococcus Epidermidis ◽  
Sigma Factor ◽  
Biofilm Formation ◽  
Negative Regulator ◽  
Transcriptional Analysis ◽  
Phenotypic Characterization ◽  
Growth Media ◽  
Alternative Sigma Factor ◽  
Independent Manner ◽  
Regulatory Cascade

ABSTRACT Transposon mutagenesis of rsbU leads to a biofilm-negative phenotype in Staphylococcus epidermidis. However, the pathway of this regulatory mechanism was unknown. To investigate the role of RsbU in the regulation of the alternative sigma factor σB and biofilm formation, we generated different mutants of the σB operon in S. epidermidis strains 1457 and 8400. The genes rsbU, rsbV, rsbW, and sigB, as well as the regulatory cascade rsbUVW and the entire σB operon, were deleted. Transcriptional analysis of sarA and the σB-dependent gene asp23 revealed the functions of RsbU and RsbV as positive regulators and of RsbW as a negative regulator of σB activity, indicating regulation of σB activity similar to that characterized for Bacillus subtilis and Staphylococcus aureus. Phenotypic characterization of the mutants revealed that the dramatic decrease of biofilm formation in rsbU mutants is mediated via σB, indicating a crucial role for σB in S. epidermidis pathogenesis. However, biofilm formation in mutants defective in σB or its function could be restored in the presence of subinhibitory ethanol concentrations. Transcriptional analysis revealed that icaR is up-regulated in mutants lacking σB function but that icaA transcription is down-regulated in these mutants, indicating a σB-dependent regulatory intermediate negatively regulating IcaR. Supplementation of growth media with ethanol decreased icaR transcription, leading to increased icaA transcription and a biofilm-positive phenotype, indicating that the ethanol-dependent induction of biofilm formation is mediated by IcaR. This icaR-dependent regulation under ethanol induction is mediated in a σB-independent manner, suggesting at least one additional regulatory intermediate in the biofilm formation of S. epidermidis.

scholarly journals Disintegration of Staphylococcus epidermidis Biofilms under Glucose-Limiting Conditions Depends on the Activity of the Alternative Sigma Factor σB

2005 ◽  
Vol 71 (9) ◽  
pp. 5577-5581 ◽  
Author(s):  
Sebastian Jäger ◽  
Dietrich Mack ◽  
Holger Rohde ◽  
Matthias A. Horstkotte ◽  
Johannes K.-M. Knobloch
Keyword(s):  
Energy Storage ◽  
Nutrient Limitation ◽  
Staphylococcus Epidermidis ◽  
Sigma Factor ◽  
Alternative Sigma Factor ◽  
Polysaccharide Intercellular Adhesin ◽  
Slow Decay ◽  
The Stability

ABSTRACT To evaluate the role of the polysaccharide intercellular adhesin as an energy-storage molecule, we investigated the effect of nutrient limitation on S. epidermidis biofilms. The stability of established biofilms depends on σB activity; however, the slow decay of biofilms under conditions of nutrient limitation reveal its use as an energy-storage molecule to be unlikely.

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

2013 ◽  
Vol 79 (12) ◽  
pp. 3867-3869 ◽  
Author(s):  
Elias Dahlsten ◽  
David Kirk ◽  
Miia Lindström ◽  
Hannu Korkeala
Keyword(s):  
Stress Tolerance ◽  
Sigma Factor ◽  
Clostridium Botulinum ◽  
Alternative Sigma Factor ◽  
Strain Atcc ◽  
Content Type ◽  
Osmotic Stress Tolerance ◽  
Group I ◽  
Temperature Downshift

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.

scholarly journals Reassessing the Role of the Type II MqsRA Toxin-Antitoxin System in Stress Response and Biofilm Formation: mqsA Is Transcriptionally Uncoupled from mqsR

mBio ◽  
2019 ◽  
Vol 10 (6) ◽  
Author(s):  
Nathan Fraikin ◽  
Clothilde J. Rousseau ◽  
Nathalie Goeders ◽  
Laurence Van Melderen
Keyword(s):  
Oxidative Stress ◽  
Stress Response ◽  
Biofilm Formation ◽  
Bile Salts ◽  
Regulatory Networks ◽  
Constitutive Expression ◽  
Toxin Gene ◽  
Global Regulator ◽  
Bacterial Physiology

ABSTRACT Toxin-antitoxin (TA) systems are broadly distributed modules whose biological roles remain mostly unknown. The mqsRA system is a noncanonical TA system in which the toxin and antitoxins genes are organized in operon but with the particularity that the toxin gene precedes that of the antitoxin. This system was shown to regulate global processes such as resistance to bile salts, motility, and biofilm formation. In addition, the MqsA antitoxin was shown to be a master regulator that represses the transcription of the csgD, cspD, and rpoS global regulator genes, thereby displaying a pleiotropic regulatory role. Here, we identified two promoters located in the toxin sequence driving the constitutive expression of mqsA, allowing thereby excess production of the MqsA antitoxin compared to the MqsR toxin. Our results show that both antitoxin-specific and operon promoters are not regulated by stresses such as amino acid starvation, oxidative shock, or bile salts. Moreover, we show that the MqsA antitoxin is not a global regulator as suggested, since the expression of csgD, cspD and rpoS is similar in wild-type and ΔmqsRA mutant strains. Moreover, these two strains behave similarly in terms of biofilm formation and sensitivity to oxidative stress or bile salts. IMPORTANCE There is growing controversy regarding the role of chromosomal toxin-antitoxin systems in bacterial physiology. mqsRA is a peculiar toxin-antitoxin system, as the gene encoding the toxin precedes that of the antitoxin. This system was previously shown to play a role in stress response and biofilm formation. In this work, we identified two promoters specifically driving the constitutive expression of the antitoxin, thereby decoupling the expression of antitoxin from the toxin. We also showed that mqsRA contributes neither to the regulation of biofilm formation nor to the sensitivity to oxidative stress and bile salts. Finally, we were unable to confirm that the MqsA antitoxin is a global regulator. Altogether, our data are ruling out the involvement of the mqsRA system in Escherichia coli regulatory networks.

scholarly journals Characterization of Biofilm Formation and the Role of BCR1 in Clinical Isolates of Candida parapsilosis

2013 ◽  
Vol 13 (4) ◽  
pp. 438-451 ◽  
Author(s):  
Srisuda Pannanusorn ◽  
Bernardo Ramírez-Zavala ◽  
Heinrich Lünsdorf ◽  
Birgitta Agerberth ◽  
Joachim Morschhäuser ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Candida Parapsilosis ◽  
Clinical Isolates ◽  
Wild Type ◽  
Content Type ◽  
Initial Adhesion ◽  
High Level ◽  
Increased Susceptibility

ABSTRACT In Candida parapsilosis , biofilm formation is considered to be a major virulence factor. Previously, we determined the ability of 33 clinical isolates causing bloodstream infection to form biofilms and identified three distinct groups of biofilm-forming strains (negative, low, and high). Here, we establish two different biofilm structures among strains forming large amounts of biofilm in which strains with complex spider-like structures formed robust biofilms on different surface materials with increased resistance to fluconazole. Surprisingly, the transcription factor Bcr1, required for biofilm formation in Candida albicans and C. parapsilosis , has an essential role only in strains with low capacity for biofilm formation. Although BCR1 leads to the formation of more and longer pseudohyphae, it was not required for initial adhesion and formation of mature biofilms in strains with a high level of biofilm formation. Furthermore, an additional phenotype affected by BCR1 was the switch in colony morphology from rough to crepe, but only in strains forming high levels of biofilm. All bcr1 Δ/Δ mutants showed increased proteolytic activity and increased susceptibility to the antimicrobial peptides protamine and RP-1 compared to corresponding wild-type and complemented strains. Taken together, our results demonstrate that biofilm formation in clinical isolates of C. parapsilosis is both dependent and independent of BCR1 , but even in strains which showed a BCR1 -independent biofilm phenotype, BCR1 has alternative physiological functions.

scholarly journals Polyamine Transport and Role of potE in Response to Osmotic Stress in Escherichia coli

2000 ◽  
Vol 182 (21) ◽  
pp. 6247-6249 ◽  
Author(s):  
Dirk Schiller ◽  
Daniela Kruse ◽  
Helmut Kneifel ◽  
Reinhard Krämer ◽  
Andreas Burkovski
Keyword(s):  
Escherichia Coli ◽  
Osmotic Stress ◽  
Deletion Mutant ◽  
Transport Processes ◽  
Hyperosmotic Shock ◽  
Physiological Conditions ◽  
Polyamine Transport

ABSTRACT When transport of polyamines in Escherichia coli was examined, putrescine excretion was observed under two different physiological conditions: (i) strictly correlated to growth and (ii) following a hyperosmotic shock. Spermidine was not excreted. Characterization of a deletion mutant showed that PotE is not involved in these transport processes.

scholarly journals Staphylococcus epidermidis in Orthopedic Device Infections: The Role of Bacterial Internalization in Human Osteoblasts and Biofilm Formation

PLoS ONE ◽  
2013 ◽  
Vol 8 (6) ◽  
pp. e67240 ◽  
Author(s):  
Florent Valour ◽  
Sophie Trouillet-Assant ◽  
Jean-Philippe Rasigade ◽  
Sébastien Lustig ◽  
Emmanuel Chanard ◽  
...  
Keyword(s):  
Staphylococcus Epidermidis ◽  
Biofilm Formation ◽  
Human Osteoblasts ◽  
Orthopedic Device
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