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Pyoverdine-mediated regulation of FpvA synthesis in Pseudomonas aeruginosa: involvement of a probable extracytoplasmic-function sigma factor, FpvI.

ABSTRACT: A search of the pvd pyoverdine biosynthesis locus of Pseudomonas aeruginosa identified an open reading frame, PA2387, whose product exhibited a sequence similar to those of a number of so-called extracytoplasmic- function sigma factors responsible for siderophore-dependent expression of iron-siderophore receptors in Escherichia coli and Pseudomonas putida. Deletion of this gene, dubbed fpvI, compromised pyoverdine-dependent FpvA ferric pyoverdine receptor production and fpvA gene expression, while the cloned gene stimulated fpvA expression. A Fur-binding site was identified immediately upstream of fpvI, consistent with the observed iron-regulated expression of fpvI and fpvA.

SUBMITTER: Redly GA

PROVIDER: S-EPMC142879 | biostudies-literature | 2003 Feb

REPOSITORIES: biostudies-literature

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Pyoverdine-mediated regulation of FpvA synthesis in Pseudomonas aeruginosa: involvement of a probable extracytoplasmic-function sigma factor, FpvI.

Rédly Gyula Alan GA Poole Keith K

Journal of bacteriology 20030201 4

A search of the pvd pyoverdine biosynthesis locus of Pseudomonas aeruginosa identified an open reading frame, PA2387, whose product exhibited a sequence similar to those of a number of so-called extracytoplasmic- function sigma factors responsible for siderophore-dependent expression of iron-siderophore receptors in Escherichia coli and Pseudomonas putida. Deletion of this gene, dubbed fpvI, compromised pyoverdine-dependent FpvA ferric pyoverdine receptor production and fpvA gene expression, whi ...[more]

PMID: 12562796

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FpvA receptor involvement in pyoverdine biosynthesis in Pseudomonas aeruginosa.

Project description:Alignment of the Pseudomonas aeruginosa ferric pyoverdine receptor, FpvA, with similar ferric-siderophore receptors revealed that the mature protein carries an extension of ca. 70 amino acids at its N terminus, an extension shared by the ferric pseudobactin receptors of P. putida. Deletion of fpvA from the chromosome of P. aeruginosa reduced pyoverdine production in this organism, as a result of a decline in expression of genes (e.g., pvdD) associated with the biosynthesis of the pyoverdine peptide moiety. Wild-type fpvA restored pvd expression in the mutant, thereby complementing its pyoverdine deficiency, although a deletion derivative of fpvA encoding a receptor lacking the N terminus of the mature protein did not. The truncated receptor was, however, functional in pyoverdine-mediated iron uptake, as evidenced by its ability to promote pyoverdine-dependent growth in an iron-restricted medium. These data are consistent with the idea that the N-terminal extension plays a role in FpvA-mediated pyoverdine biosynthesis in P. aeruginosa.

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A Novel extracytoplasmic function (ECF) sigma factor regulates virulence in Pseudomonas aeruginosa.

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A novel extracytoplasmic function (ECF) sigma factor regulates virulence in Pseudomonas aeruginosa

2009-04-21 | GSE15697 | GEO

Analysis of promoters recognized by PvdS, an extracytoplasmic-function sigma factor protein from Pseudomonas aeruginosa.

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Novel Pyoverdine Inhibitors Mitigate Pseudomonas aeruginosa Pathogenesis.

Project description:Pseudomonas aeruginosa is a clinically important pathogen that causes a variety of infections, including urinary, respiratory, and other soft-tissue infections, particularly in hospitalized patients with immune defects, cystic fibrosis, or significant burns. Antimicrobial resistance is a substantial problem in P. aeruginosa treatment due to the inherent insensitivity of the pathogen to a wide variety of antimicrobial drugs and its rapid acquisition of additional resistance mechanisms. One strategy to circumvent this problem is the use of anti-virulent compounds to disrupt pathogenesis without directly compromising bacterial growth. One of the principle regulatory mechanisms for P. aeruginosa's virulence is the iron-scavenging siderophore pyoverdine, as it governs in-host acquisition of iron, promotes expression of multiple virulence factors, and is directly toxic. Some combination of these activities renders pyoverdine indispensable for pathogenesis in mammalian models. Here we report identification of a panel of novel small molecules that disrupt pyoverdine function. These molecules directly act on pyoverdine, rather than affecting its biosynthesis. The compounds reduce the pathogenic effect of pyoverdine and improve the survival of Caenorhabditis elegans when challenged with P. aeruginosa by disrupting only this single virulence factor. Finally, these compounds can synergize with conventional antimicrobials, forming a more effective treatment. These compounds may help to identify, or be modified to become, viable drug leads in their own right. Finally, they also serve as useful tool compounds to probe pyoverdine activity.

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A novel extracytoplasmic function (ECF) sigma factor regulates virulence in Pseudomonas aeruginosa

2009-04-21 | E-GEOD-15697 | biostudies-arrayexpress

Characterization of a gene encoding an acetylase required for pyoverdine synthesis in Pseudomonas aeruginosa.

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Project description:A putative operon of four genes implicated in the synthesis of the chromophore moiety of the Pseudomonas aeruginosa siderophore pyoverdine, dubbed pvcABCD (where pvc stands for pyoverdine chromophore), was cloned and sequenced. Mutational inactivation of the pvc genes abrogated pyoverdine biosynthesis, consistent with their involvement in the biosynthesis of this siderophore. pvcABCD expression was negatively regulated by iron and positively regulated by both PvdS, the alternate sigma factor required for pyoverdine biosynthesis, and PtxR, a LysR family activator previously implicated in exotoxin A regulation.

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The extracytoplasmic function sigma factor σ<sup>VreI</sup> is active during infection and contributes to phosphate starvation-induced virulence of Pseudomonas aeruginosa.

Project description:The extracytoplasmic function sigma factor σVreI of the human pathogen Pseudomonas aeruginosa promotes transcription of potential virulence determinants, including secretion systems and secreted proteins. Its activity is modulated by the VreR anti-σ factor that inhibits the binding of σVreI to the RNA polymerase in the absence of a (still unknown) inducing signal. The vreI-vreR genes are expressed under inorganic phosphate (Pi) starvation, a physiological condition often encountered in the host that increases P. aeruginosa pathogenicity. However, whether or not σVreI is active in vivo during infection and contributes to the Pi starvation-induced virulence of this pathogen has not been analyzed yet. Using zebrafish embryos and a human alveolar basal epithelial cell line as P. aeruginosa hosts, we demonstrate in this work that σVreI is active during infection and that lack of σVreI considerably reduces the Pi starvation-induced virulence of this pathogen. Surprisingly, lack of the σVreI inhibitor, the VreR anti-σ factor, also diminishes the virulence of P. aeruginosa. By transcriptomic analyses we show that VreR modulates gene expression not only in a σVreI-dependent but also in a σVreI-independent manner. This includes potential virulence determinants and transcriptional regulators that could be responsible for the reduced virulence of the ΔvreR mutant.

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