Molecular insight into the activity of LasR protein from Pseudomonas aeruginosa in the regulation of virulence gene expression by this organism

Gene ◽  
2016 ◽  
Vol 580 (1) ◽  
pp. 80-87 ◽  
Author(s):  
Nilkanta Chowdhury ◽  
Angshuman Bagchi
Keyword(s):  
Gene Expression ◽  
Pseudomonas Aeruginosa ◽  
Virulence Gene ◽  
Virulence Gene Expression ◽  
Insight Into

scholarly journals Swarming of Pseudomonas aeruginosa Is Controlled by a Broad Spectrum of Transcriptional Regulators, Including MetR

2009 ◽  
Vol 191 (18) ◽  
pp. 5592-5602 ◽  
Author(s):  
Amy T. Y. Yeung ◽  
Ellen C. W. Torfs ◽  
Farzad Jamshidi ◽  
Manjeet Bains ◽  
Irith Wiegand ◽  
...  
Keyword(s):  
Gene Expression ◽  
Pseudomonas Aeruginosa ◽  
Virulence Gene ◽  
Swarming Motility ◽  
Regulatory Mutants ◽  
Virulence Gene Expression ◽  
Type Iv ◽  
Genes Encoding ◽  
Regulator Genes ◽  
Transposon Insertions

ABSTRACT Pseudomonas aeruginosa exhibits swarming motility on semisolid surfaces (0.5 to 0.7% agar). Swarming is a more than just a form of locomotion and represents a complex adaptation resulting in changes in virulence gene expression and antibiotic resistance. In this study, we used a comprehensive P. aeruginosa PA14 transposon mutant library to investigate how the complex swarming adaptation process is regulated. A total of 233 P. aeruginosa PA14 transposon mutants were verified to have alterations in swarming motility. The swarming-associated genes functioned not only in flagellar or type IV pilus biosynthesis but also in processes as diverse as transport, secretion, and metabolism. Thirty-three swarming-deficient and two hyperswarming mutants had transposon insertions in transcriptional regulator genes, including genes encoding two-component sensors and response regulators; 27 of these insertions were newly identified. Of the 25 regulatory mutants whose swarming motility was highly impaired (79 to 97%), only 1 (a PA1458 mutant) had a major defect in swimming, suggesting that this regulator might influence flagellar synthesis or function. Twitching motility, which requires type IV pili, was strongly affected in only two regulatory mutants (pilH and PA2571 mutants) and was moderately affected in three other mutants (algR, ntrB, and nosR mutants). Microarray analyses were performed to compare the gene expression profile of a swarming-deficient PA3587 mutant to that of the wild-type PA14 strain under swarming conditions. PA3587 showed 63% homology to metR, which encodes a regulator of methionine biosynthesis in Escherichia coli. The observed dysregulation in the metR mutant of nine different genes required for swarming motility provided a possible explanation for the swarming-deficient phenotype of this mutant.

scholarly journals Advancing the Quorum in Pseudomonas aeruginosa: MvaT and the Regulation of N-Acylhomoserine Lactone Production and Virulence Gene Expression

2002 ◽  
Vol 184 (10) ◽  
pp. 2576-2586 ◽  
Author(s):  
Stephen P. Diggle ◽  
Klaus Winzer ◽  
Andrée Lazdunski ◽  
Paul Williams ◽  
Miguel Cámara
Keyword(s):  
Gene Expression ◽  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Growth Phase ◽  
Virulence Gene ◽  
Homoserine Lactone ◽  
Logarithmic Phase ◽  
Signal Molecules ◽  
Virulence Gene Expression ◽  
Acylhomoserine Lactone

ABSTRACT Pseudomonas aeruginosa regulates the production of many exoproteins and secondary metabolites via a hierarchical quorum-sensing cascade through LasR and RhlR and their cognate signal molecules N-(3-oxododecanoyl)-l-homoserine lactone (3O-C12-HSL) and N-(butanoyl)-l-homoserine lactone (C4-HSL). In this study, we found that transcription of the quorum sensing-regulated genes lecA (coding for PA-IL lectin), lasB (coding for elastase), and rpoS appeared to be growth phase dependent and their expression could not be advanced to the logarithmic phase in cells growing in batch culture by the addition of exogenous C4-HSL and 3O-C12-HSL. To identify novel regulators responsible for this growth phase dependency, a P. aeruginosa lecA::lux reporter strain was subjected to random transposon mutagenesis. A number of mutants affected in lecA expression were found that exhibited altered production of multiple quorum sensing-dependent phenotypes. While some mutations were mapped to new loci such as clpA and mvaT and a putative efflux system, a number of mutations were also mapped to known regulators such as lasR, rhlR, and rpoS. MvaT was identified as a novel global regulator of virulence gene expression, as a mutation in mvaT resulted in enhanced lecA expression and pyocyanin production. This mutant also showed altered swarming ability and production of the LasB and LasA proteases, 3O-C12-HSL, and C4-HSL. Furthermore, addition of exogenous 3O-C12-HSL and C4-HSL to the mvaT mutant significantly advanced lecA expression, suggesting that MvaT is involved in the growth phase-dependent regulation of the lecA gene.

scholarly journals Differential Expression and Roles of Staphylococcus aureus Virulence Determinants during Colonization and Disease

mBio ◽  
2015 ◽  
Vol 6 (1) ◽  
Author(s):  
Amy Jenkins ◽  
Binh An Diep ◽  
Thuy T. Mai ◽  
Nhung H. Vo ◽  
Paul Warrener ◽  
...  
Keyword(s):  
Gene Expression ◽  
Staphylococcus Aureus ◽  
Virulence Gene ◽  
Nasal Colonization ◽  
Virulence Determinants ◽  
Content Type ◽  
Virulence Gene Expression ◽  
Invasive Pathogen ◽  
Knockout Mutants ◽  
Insight Into

ABSTRACTStaphylococcus aureusis a Gram-positive, commensal bacterium known to asymptomatically colonize the human skin, nares, and gastrointestinal tract. Colonized individuals are at increased risk for developing S. aureus infections, which range from mild skin and soft tissue infections to more severe diseases, such as endocarditis, bacteremia, sepsis, and osteomyelitis. Different virulence factors are required for S. aureus to infect different body sites. In this study, virulence gene expression was analyzed in two S. aureus isolates during nasal colonization, bacteremia and in the heart during sepsis. These models were chosen to represent the stepwise progression of S. aureus from an asymptomatic colonizer to an invasive pathogen. Expression of 23 putative S. aureus virulence determinants, representing protein and carbohydrate adhesins, secreted toxins, and proteins involved in metal cation acquisition and immune evasion were analyzed. Consistent upregulation ofsdrC,fnbA,fhuD,sstD, andhlawas observed in the shift between colonization and invasive pathogen, suggesting a prominent role for these genes in staphylococcal pathogenesis. Finally, gene expression data were correlated to the roles of the genes in pathogenesis by using knockout mutants in the animal models. These results provide insights into how S. aureus modifies virulence gene expression between commensal and invasive pathogens.IMPORTANCEMany bacteria, such asStaphylococcus aureus, asymptomatically colonize human skin and nasal passages but can also cause invasive diseases, such as bacteremia, pneumonia, sepsis, and osteomyelitis. The goal of this study was to analyze differences in the expression of selected S. aureus genes during a commensal lifestyle and as an invasive pathogen to gain insight into the commensal-to-pathogen transition and how a bacterial pathogen adapts to different environments within a host (e.g., from nasal colonization to invasive pathogen). The gene expression data were also used to select genes for which to construct knockout mutants to assess the role of several proteins in nasal colonization and lethal bacteremia. These results not only provide insight into the factors involved in S. aureus disease pathogenesis but also provide potential therapeutic targets.

scholarly journals Pseudomonas aeruginosa AES-1 Exhibits Increased Virulence Gene Expression during Chronic Infection of Cystic Fibrosis Lung

PLoS ONE ◽  
2011 ◽  
Vol 6 (9) ◽  
pp. e24526 ◽  
Author(s):  
Sharna Naughton ◽  
Dane Parker ◽  
Torsten Seemann ◽  
Torsten Thomas ◽  
Lynne Turnbull ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Chronic Infection ◽  
Virulence Gene ◽  
Cystic Fibrosis Lung ◽  
Virulence Gene Expression

scholarly journals Vfr Directly ActivatesexsATranscription To Regulate Expression of the Pseudomonas aeruginosa Type III Secretion System

2016 ◽  
Vol 198 (9) ◽  
pp. 1442-1450 ◽  
Author(s):  
Anne E. Marsden ◽  
Peter J. Intile ◽  
Kayley H. Schulmeyer ◽  
Ethan R. Simmons-Patterson ◽  
Mark L. Urbanowski ◽  
...  
Keyword(s):  
Gene Expression ◽  
Pseudomonas Aeruginosa ◽  
Type Iii Secretion ◽  
Virulence Gene ◽  
Type Iv Pili ◽  
Global Regulator ◽  
Content Type ◽  
Virulence Gene Expression ◽  
Type Iii ◽  
Type Iv

ABSTRACTThePseudomonas aeruginosacyclic AMP (cAMP)-Vfr system (CVS) is a global regulator of virulence gene expression. Regulatory targets include type IV pili, secreted proteases, and the type III secretion system (T3SS). The mechanism by which CVS regulates T3SS gene expression remains undefined. Single-cell expression studies previously found that only a portion of the cells within a population express the T3SS under inducing conditions, a property known as bistability. We now report that bistability is altered in avfrmutant, wherein a substantially smaller fraction of the cells express the T3SS relative to the parental strain. Since bistability usually involves positive-feedback loops, we tested the hypothesis that virulence factor regulator (Vfr) regulates the expression ofexsA. ExsA is the central regulator of T3SS gene expression and autoregulates its own expression. AlthoughexsAis the last gene of theexsCEBApolycistronic mRNA, we demonstrate that Vfr directly activatesexsAtranscription from a second promoter (PexsA) located immediately upstream ofexsA. PexsApromoter activity is entirely Vfr dependent. Direct binding of Vfr to a PexsApromoter probe was demonstrated by electrophoretic mobility shift assays, and DNase I footprinting revealed an area of protection that coincides with a putative Vfr consensus-binding site. Mutagenesis of that site disrupted Vfr binding and PexsApromoter activity. We conclude that Vfr contributes to T3SS gene expression through activation of the PexsApromoter, which is internal to the previously characterizedexsCEBAoperon.IMPORTANCEVfr is a cAMP-dependent DNA-binding protein that functions as a global regulator of virulence gene expression inPseudomonas aeruginosa. Regulation by Vfr allows for the coordinate production of related virulence functions, such as type IV pili and type III secretion, required for adherence to and intoxication of host cells, respectively. Although the molecular mechanism of Vfr regulation has been defined for many target genes, a direct link between Vfr and T3SS gene expression had not been established. In the present study, we report that Vfr directly controlsexsAtranscription, the master regulator of T3SS gene expression, from a newly identified promoter located immediately upstream ofexsA.

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