Quorum-sensing and siderophore biosynthesis in Pseudomonas aeruginosa: lasRllasI mutants exhibit reduced pyoverdine biosynthesis

Stintzi, Alain

doi:10.1016/s0378-1097(98)00352-8

Cited by 81 publications

(99 citation statements)

References 6 publications

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“…PvdS regulates expression of genes required for pyoverdine production, and is therefore upregulated when P. aeruginosa is in an iron-deficient environment. Pyoverdine upregulates production of itself as well as protease IV (Lamont et al, 2002) and its synthesis is also controlled by lasRI (Stintzi et al, 1998). In the current study, the lowprotease-producing isolates also demonstrated low pyoverdine production.…”

Section: Discussionmentioning

confidence: 99%

“…Controlled expression of several key P. aeruginosa virulence factors, including elastase (lasB) (Pearson et al, 1997), exotoxin A , type II secretory pathway proteins (xcp) (Chapon-Hervé et al, 1997) and pyoverdine (Kim et al, 2005;Stintzi et al, 1998) are mediated by population density bio-sensor mechanisms, a process known as quorum sensing. P. aeruginosa has two quorum-sensing systems, the Las and Rhl systems, each influencing the expression of a range of virulence factors (Passador et al, 1993;Pearson et al, 1994).…”

Section: Introductionmentioning

confidence: 99%

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Characterization of protease IV expression in Pseudomonas aeruginosa clinical isolates

Conibear

Willcox

Flanagan

et al. 2012

Journal of Medical Microbiology

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Expression of protease IV by Pseudomonas aeruginosa during ocular infections contributes significantly to tissue damage. However, several P. aeruginosa strains isolated from ocular infections or inflammatory events produce very low levels of protease IV. The aim of the present study was to characterize, genetically and phenotypically, the presence and expression of the protease IV gene in a group of clinical isolates that cause adverse ocular events of varying degrees, and to elucidate the possible control mechanisms of expression associated with this virulence factor. Protease IV gene sequences from seven clinical isolates of P. aeruginosa were determined and compared to P. aeruginosa strains PAO1 and PA103-29. Production and enzyme activity of protease IV were measured in test strains and compared to that of quorumsensing gene (lasRI) mutants and the expression of other virulence factors. Protease IV gene sequence similarities between the isolates were 97.5-99.5 %. The strains were classified into two distinct phylogenetic groups that correlated with the presence of exo-enzymes from type three secretion systems (TTSS). Protease IV concentrations produced by PAODlasRI mutants and the two clinical isolates with a lasRI gene deficiency were restored to levels comparable to strain PAO1 following complementation of the quorum-sensing gene deficiencies. The protease IV gene is highly conserved in P. aeruginosa clinical isolates that cause a range of adverse ocular events. Observed variations within the gene sequence appear to correlate with presence of specific TTSS genes. Protease IV expression was shown to be regulated by the Las quorum-sensing system. INTRODUCTIONInflammation and infection in the cornea (keratitis) arising from Pseudomonas aeruginosa infection can lead rapidly to scarring and loss of sight unless prompt and targeted treatment is initiated (Sankaridurg et al., 2000). P. aeruginosa virulence is attributed, in part, to the production of several destructive proteins and stimulation of host immune response in the ocular tissues (Hazlett, 2002). The virulence factors most commonly associated with P. aeruginosa-induced ocular damage are exo-enzymes S (exoS) and U (exoU) (Fleiszig et al., 1997), elastase (lasB) (Kessler & Blumberg, 1987), alkaline protease (aprA) (Twining et al., 1993) and protease IV (piv) (O'Callaghan et al., 1996). Another protease, P. aeruginosa small protease (PASP), can also cause rapid corneal damage (Marquart et al., 2005). Other important pathogenic mechanisms include the genes involved in translocation and activation of virulence proteins via the type II (xcp) and type III secretory pathways (Sandkvist, 2001;Yahr et al., 1997).Protease IV is a lysine-specific endoprotease and a significant virulence factor for pathogenesis of P. aeruginosa in the eye and lung (Caballero et al., 2004; Engel et al., 1997;Wilderman et al., 2001). Mature protease IV degrades important host immunological proteins such as complement and IgG (Engel et al., 1998). Protease IV also compromises the inte...

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Characterization of protease IV expression in Pseudomonas aeruginosa clinical isolates

Conibear

Willcox

Flanagan

et al. 2012

Journal of Medical Microbiology

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“…Hence, some of the observed alterations in the transcriptome profile of the rsmA mutant may be due to the direct effect of the rsmA mutation on the QS network, since RsmA negatively regulates lasI and rhlI . For example, the increase in 3-oxo-C12-HSL in the rsmA mutant ) may contribute to the increase in expression of the pyoverdine biosynthetic genes (Stintzi et al, 1998;Whiteley et al, 1999) and sodM (Hassett et al, 1999), both regulated by the QS system. However, although inactivation of rsmA affects AHL synthesis, this does not appear to have a dramatic effect on expression of all QSregulated genes.…”

Section: Discussionmentioning

confidence: 99%

Influence of the regulatory protein RsmA on cellular functions in Pseudomonas aeruginosa PAO1, as revealed by transcriptome analysis

et al. 2006

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RsmA is a posttranscriptional regulatory protein in Pseudomonas aeruginosa that works in tandem with a small non-coding regulatory RNA molecule, RsmB (RsmZ), to regulate the expression of several virulence-related genes, including the N-acyl-homoserine lactone synthase genes lasI and rhlI, and the hydrogen cyanide and rhamnolipid biosynthetic operons. Although these targets of direct RsmA regulation have been identified, the full impact of RsmA on cellular activities is not as yet understood. To address this issue the transcriptome profiles of P. aeruginosa PAO1 and an isogenic rsmA mutant were compared. Loss of RsmA altered the expression of genes involved in a variety of pathways and systems important for virulence, including iron acquisition, biosynthesis of the Pseudomonas quinolone signal (PQS), the formation of multidrug efflux pumps, and motility. Not all of these effects can be explained through the established regulatory roles of RsmA. This study thus provides both a first step towards the identification of further genes under RsmA posttranscriptional control in P. aeruginosa and a fuller understanding of the broader impact of RsmA on cellular functions.

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“…Many bacteria secrete iron-chelating molecules to acquire iron for their own growth. Siderophores are low-molecular-weight iron-chelating compounds, and their production is reportedly controlled by quorum sensing (13,32). To examine whether siderophore synthesis in P. syringae pv.…”

Section: Detection Of Ahls and Northern Analysismentioning

confidence: 99%

“…Iron uptake using siderophores has been reported to be regulated by the quorum-sensing system in P. aeruginosa (32). Because environmental iron is almost insoluble at biological pH, many bacteria have developed systems to acquire iron by using siderophores, which show high affinity for iron(III) (28).…”

Section: Vol 188 2006mentioning

confidence: 99%

A Homologue of the 3-Oxoacyl-(Acyl Carrier Protein) Synthase III Gene Located in the Glycosylation Island of Pseudomonas syringae pv. tabaci Regulates Virulence Factors via N -Acyl Homoserine Lactone and Fatty Acid Synthesis

et al. 2006

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Pseudomonas syringae pv. tabaci 6605 possesses a genetic region involved in flagellin glycosylation. This region is composed of three open reading frames: orf1, orf2, and orf3. Our previous study revealed that orf1 and orf2 encode glycosyltransferases; on the other hand, orf3 has no role in posttranslational modification of flagellin. Although the function of Orf3 remained unclear, an orf3 deletion mutant (⌬orf3 mutant) had reduced virulence on tobacco plants. Orf3 shows significant homology to a 3-oxoacyl-(acyl carrier protein) synthase III in the fatty acid elongation cycle. The ⌬orf3 mutant had a significantly reduced ability to form acyl homoserine lactones (AHLs), which are quorum-sensing molecules, suggesting that Orf3 is required for AHL synthesis. In comparison with the wild-type strain, swarming motility, biosurfactant production, and tolerance to H 2 O 2 and antibiotics were enhanced in the ⌬orf3 mutant. A scanning electron micrograph of inoculated bacteria on the tobacco leaf surface revealed that there is little extracellular polymeric substance matrix surrounding the cells in the ⌬orf3 mutant. The phenotypes of the ⌬orf3 mutant and an AHL synthesis (⌬psyI) mutant were similar, although the mutant-specific characteristics were more extreme in the ⌬orf3 mutant. The swarming motility of the ⌬orf3 mutant was greater than that of the ⌬psyI mutant. This was attributed to the synergistic effects of the overproduction of biosurfactants and/or alternative fatty acid metabolism in the ⌬orf3 mutant. Furthermore, the amounts of iron and biosurfactant seem to be involved in biofilm development under quorum-sensing regulation in P. syringae pv. tabaci 6605.Pseudomonas syringae pv. tabaci 6605, an phytopathogenic bacterial isolate, causes wildfire disease on host tobacco plants and induces a hypersensitive reaction (HR) on nonhost plants.In previous studies, we demonstrated that flagellin, a component of the flagellar filament, is a major elicitor of HR by P. syringae pv. tabaci 6605 (30, 35). Flagellin of P. syringae pv. tabaci 6605 induces HR on nonhost plants but not on its host tobacco plant. Although the deduced amino acid sequence of P. syringae pv. glycinea race 4 flagellin (FliC) is identical to that of P. syringae pv. tabaci 6605 flagellin, the flagellin of P. syringae pv. glycinea does induce HR on tobacco plants, suggesting that posttranslational modification of flagellin determines the specificity to induce HR (34). We recently reported that genes existing upstream of fliC, which encodes flagellin protein, are involved in the glycosylation of flagellin in these two pathovars (33, 36). There are three open reading frames, namely, orf1, orf2, and orf3, in the glycosylation islands of P. syringae pv. tabaci and pv. glycinea (Fig. 1). Because the proteins encoded by orf1 and orf2 showed homology to a putative glycosyltransferase and the molecular mass of the flagellin of each orf1 and orf2 deletion mutant (⌬orf1 and ⌬orf2 mutants) was decreased, these genes are thought to encode the glycosyltransferases. I...

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Quorum-sensing and siderophore biosynthesis in Pseudomonas aeruginosa: lasRllasI mutants exhibit reduced pyoverdine biosynthesis

Cited by 81 publications

References 6 publications

Characterization of protease IV expression in Pseudomonas aeruginosa clinical isolates

Characterization of protease IV expression in Pseudomonas aeruginosa clinical isolates

Influence of the regulatory protein RsmA on cellular functions in Pseudomonas aeruginosa PAO1, as revealed by transcriptome analysis

A Homologue of the 3-Oxoacyl-(Acyl Carrier Protein) Synthase III Gene Located in the Glycosylation Island of Pseudomonas syringae pv. tabaci Regulates Virulence Factors via N -Acyl Homoserine Lactone and Fatty Acid Synthesis

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