Genetically programmed autoinducer destruction reduces virulence gene expression and swarming motility in Pseudomonas aeruginosa PAO1 The GenBank accession number for the aiiA nucleotide sequence is AF397400. The GenBank accession numbers for the nucleotide sequences of the 16S rRNA genes of strains A23 and A24 are AF397398 and AF397399.

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.

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The transcriptional activator HIyU of Vibrio cholerae: nucleotide sequence and role in virulence gene expression

Molecular Microbiology ◽

10.1111/j.1365-2958.1993.tb01735.x ◽

1993 ◽

Vol 9 (4) ◽

pp. 751-760 ◽

Cited By ~ 54

Author(s):

S. G. Williams ◽

S. R. Attridge ◽

P. A. Manning

Keyword(s):

Gene Expression ◽

Nucleotide Sequence ◽

Vibrio Cholerae ◽

Virulence Gene ◽

Transcriptional Activator ◽

Virulence Gene Expression

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

Gene ◽

10.1016/j.gene.2015.12.067 ◽

2016 ◽

Vol 580 (1) ◽

pp. 80-87 ◽

Cited By ~ 14

Author(s):

Nilkanta Chowdhury ◽

Angshuman Bagchi

Keyword(s):

Gene Expression ◽

Pseudomonas Aeruginosa ◽

Virulence Gene ◽

Virulence Gene Expression ◽

Insight Into

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

Journal of Bacteriology ◽

10.1128/jb.184.10.2576-2586.2002 ◽

2002 ◽

Vol 184 (10) ◽

pp. 2576-2586 ◽

Cited By ~ 182

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.

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Molecular Signature of Differential Virulence in Natural Isolates of Erwinia amylovora

Phytopathology ◽

10.1094/phyto-100-2-0192 ◽

2010 ◽

Vol 100 (2) ◽

pp. 192-198 ◽

Cited By ~ 32

Author(s):

Dongping Wang ◽

Schuyler S. Korban ◽

Youfu Zhao

Keyword(s):

Gene Expression ◽

Erwinia Amylovora ◽

Virulence Gene ◽

Molecular Signature ◽

Molecular Signatures ◽

Swarming Motility ◽

Disease Symptoms ◽

Virulence Gene Expression ◽

Root Stock ◽

Natural Isolates

Erwinia amylovora, the causal agent of fire blight, is considered to be a genetically homogeneous species based on physiological, biochemical, phylogenetic, and genetic analysis. However, E. amylovora strains exhibiting differential virulence are isolated from nature. The exopolysaccharide amylovoran and type III secretion system (T3SS) are two major yet separate virulence factors in E. amylovora. The objective of this study was to investigate whether there is a correlation between E. amylovora virulence and levels of virulence gene expression. Four wild-type strains (Ea1189, Ea273, Ea110, and CFBP1430), widely used in studies of E. amylovora pathogenesis, have been analyzed and compared. E. amylovora strains Ea273 and Ea110 elicited higher severity of disease symptoms than those of Ea1189 and CFBP1430 on apple cv. Golden Delicious and G16 apple root stock plants but not on susceptible Gala plants. In addition, Ea273 and Ea110 elicited severe hypersensitive responses within shorter periods of time at lower inoculum concentrations than those of Ea1189 and CFBP1430 on tobacco plants. Further molecular analyses have revealed that amylovoran production and expression of both amylovoran (amsG) and T3SS (dspE and hrpL) genes were significantly higher in Ea273 and Ea110 than those in Ea1189 and CFBP1430. Other phenotypes such as swarming motility in these four strains also differed significantly. These results indicate that E. amylovora strains of different origin can be divided into subgroups based on molecular signatures of virulence gene expression. Therefore, these molecular signatures may be used to differentiate E. amylovora strains, which may have taxonomical and evolutionary implications.

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Swarming of Pseudomonas aeruginosa Is a Complex Adaptation Leading to Increased Production of Virulence Factors and Antibiotic Resistance

Journal of Bacteriology ◽

10.1128/jb.01659-07 ◽

2008 ◽

Vol 190 (8) ◽

pp. 2671-2679 ◽

Cited By ~ 222

Author(s):

Joerg Overhage ◽

Manjeet Bains ◽

Michelle D. Brazas ◽

Robert E. W. Hancock

Keyword(s):

Gene Expression ◽

Pseudomonas Aeruginosa ◽

Antibiotic Resistance ◽

Expression Profiles ◽

Expression Patterns ◽

Leading Edge ◽

Adaptation Process ◽

Extracellular Proteases ◽

Swarming Motility ◽

Virulence Gene Expression

ABSTRACT In addition to exhibiting swimming and twitching motility, Pseudomonas aeruginosa is able to swarm on semisolid (viscous) surfaces. Recent studies have indicated that swarming is a more complex type of motility influenced by a large number of different genes. To investigate the adaptation process involved in swarming motility, gene expression profiles were analyzed by performing microarrays on bacteria from the leading edge of a swarm zone compared to bacteria growing in identical medium under swimming conditions. Major shifts in gene expression patterns were observed under swarming conditions, including, among others, the overexpression of a large number of virulence-related genes such as those encoding the type III secretion system and its effectors, those encoding extracellular proteases, and those associated with iron transport. In addition, swarming cells exhibited adaptive antibiotic resistance against polymyxin B, gentamicin, and ciprofloxacin compared to what was seen for their planktonic (swimming) counterparts. By analyzing a large subset of up-regulated genes, we were able to show that two virulence genes, lasB and pvdQ, were required for swarming motility. These results clearly favored the conclusion that swarming of P. aeruginosa is a complex adaptation process in response to a viscous environment resulting in a substantial change in virulence gene expression and antibiotic resistance.

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