-
Environmental Microbiology Jan 2015
Topics: Humans; Pseudomonas Infections; Pseudomonas aeruginosa; Virulence; Virulence Factors
PubMed: 25297499
DOI: 10.1111/1462-2920.12620 -
Proceedings of the National Academy of... Nov 2014Pseudomonas aeruginosa infects every type of host that has been examined by deploying multiple virulence factors. Previous studies of virulence regulation have largely...
Pseudomonas aeruginosa infects every type of host that has been examined by deploying multiple virulence factors. Previous studies of virulence regulation have largely focused on chemical cues, but P. aeruginosa may also respond to mechanical cues. Using a rapid imaging-based virulence assay, we demonstrate that P. aeruginosa activates virulence in response to attachment to a range of chemically distinct surfaces, suggesting that this bacterial species responds to mechanical properties of its substrates. Surface-activated virulence requires quorum sensing, but activating quorum sensing does not induce virulence without surface attachment. The activation of virulence by surfaces also requires the surface-exposed protein PilY1, which has a domain homologous to a eukaryotic mechanosensor. Specific mutation of the putative PilY1 mechanosensory domain is sufficient to induce virulence in non-surface-attached cells, suggesting that PilY1 mediates surface mechanotransduction. Triggering virulence only when cells are both at high density and attached to a surface—two host-nonspecific cues—explains how P. aeruginosa precisely regulates virulence while maintaining broad host specificity.
Topics: Bacterial Adhesion; Pseudomonas aeruginosa; Quorum Sensing; Virulence
PubMed: 25385640
DOI: 10.1073/pnas.1415712111 -
Annales Francaises D'anesthesie Et de... Jun 2003
Review
Topics: Humans; Opportunistic Infections; Pseudomonas Infections; Pseudomonas aeruginosa; Virulence Factors
PubMed: 12893377
DOI: 10.1016/s0750-7658(03)00168-0 -
MBio Jun 2015Phenotypic variability among bacteria depends on gene expression in response to different environments, and it also reflects differences in genomic structure. In this...
UNLABELLED
Phenotypic variability among bacteria depends on gene expression in response to different environments, and it also reflects differences in genomic structure. In this study, we analyzed transcriptome sequencing (RNA-seq) profiles of 151 Pseudomonas aeruginosa clinical isolates under standard laboratory conditions and of one P. aeruginosa type strain under 14 different environmental conditions. Our approach allowed dissection of the impact of the genetic background versus environmental cues on P. aeruginosa gene expression profiles and revealed that phenotypic variation was larger in response to changing environments than between genomically different isolates. We demonstrate that mutations within the global regulator LasR affect more than one trait (pleiotropy) and that the interaction between mutations (epistasis) shapes the P. aeruginosa phenotypic plasticity landscape. Because of pleiotropic and epistatic effects, average genotype and phenotype measures appeared to be uncorrelated in P. aeruginosa.
IMPORTANCE
This work links experimental data of unprecedented complexity with evolution theory and delineates the transcriptional landscape of the opportunistic pathogen Pseudomonas aeruginosa. We found that gene expression profiles are most strongly influenced by environmental cues, while at the same time the transcriptional profiles were also shaped considerably by genetic variation within global regulators. The comprehensive set of transcriptomic and genomic data of more than 150 clinical P. aeruginosa isolates will be made publically accessible to all researchers via a dedicated web interface. Both Pseudomonas specialists interested in expression and regulation of specific genes and researchers from other fields with more global interest in the phenotypic and genotypic variation of this important model species can access all information on various levels of detail.
Topics: Adaptation, Physiological; Epistasis, Genetic; Gene Expression Profiling; Gene Expression Regulation, Bacterial; Gene Regulatory Networks; Genetic Variation; Genotype; Molecular Sequence Data; Phenotype; Pseudomonas aeruginosa; Sequence Analysis, DNA
PubMed: 26126853
DOI: 10.1128/mBio.00749-15 -
The Journal of Antimicrobial... Nov 1997Pseudomonas aeruginosa (and various other gram-negative pathogens) liberate membrane vesicles during normal growth. These bilayered vesicles consist of endotoxin... (Review)
Review
Pseudomonas aeruginosa (and various other gram-negative pathogens) liberate membrane vesicles during normal growth. These bilayered vesicles consist of endotoxin (lipopolysaccharide), outer membrane proteins and several potent hydrolytic enzymes including protease, alkaline phosphatase, phospholipase C and peptidoglycan hydrolase. The vesicles contain pro-elastase and alkaline phosphatase (which are periplasmic constituents) and so are important for packaging periplasmic components as they are liberated to the outside of the cell. Once liberated, the vesicles are capable of fusing with the membranes of epithelial cells and liberating their virulence factors into host cells where they degrade cellular components, thereby aiding infection by the pathogen. The aminoglycoside antibiotic, gentamicin, is thought to kill bacteria by inhibiting protein synthesis, yet this cationic antibiotic can also perturb the packing order of lipids, thereby destabilizing bilayered membranes. For pathogens with highly anionic lipopolysaccharide on their surface, such as P. aeruginosa, this membrane destabilization can be so serious that it can cause cell lysis; these cells are therefore killed by a combination of protein synthesis inhibition and surface perturbation. By destabilizing the membranes of P. aeruginosa, gentamicin increases the release of membrane vesicles three- to five-fold. This may help account for some of the bacterium-mediated toxicity encountered during patient treatment with aminoglycoside antibiotics.
Topics: Aminoglycosides; Anti-Bacterial Agents; Cell Membrane; Pseudomonas aeruginosa; Virulence
PubMed: 9421308
DOI: 10.1093/jac/40.5.615 -
Lipids Sep 2019Biofilms have significance in medical, industrial, and environmental settings, and can cause important damage. As biofilms are tolerant to various stresses, including...
Biofilms have significance in medical, industrial, and environmental settings, and can cause important damage. As biofilms are tolerant to various stresses, including antibiotics, it is necessary to better understand their formation. For this reason, we characterized the phospholipidome of Pseudomonas aeruginosa, an opportunistic pathogen involved in numerous infections, during the first steps of the biofilm development. By a liquid chromatography-tandem mass spectrometry time-course analysis over a 24-h period, we compared the phospholipid (PL) composition of immobilized (attached) and planktonic (unattached) P. aeruginosa PAO1 cells. Our results showed that the PL content of P. aeruginosa PAO1 was mainly modulated by the incubation time, thus related to bacterial growth but also, more modestly, by the immobilization state. We observed that relative amounts of PL varied over time with two main profiles and that these profiles are correlated to its fatty acid composition, including the degree of unsaturation. A statistical analysis revealed that the PL contents of both attached and unattached PAO1 cells were significantly different mainly after 3 and 6 h of incubation and that the amounts of two PL presented a statistical difference between attached and unattached cells all along the 24-h period: PtdEtn 16:0_18:1 and PtdEtn 18:1_18:1.
Topics: Chromatography, Liquid; Phospholipids; Pseudomonas aeruginosa; Tandem Mass Spectrometry
PubMed: 31397925
DOI: 10.1002/lipd.12184 -
Genome Biology and Evolution Apr 2020Extensive use of next-generation sequencing has the potential to transform our knowledge on how genomic variation within bacterial species impacts phenotypic...
Extensive use of next-generation sequencing has the potential to transform our knowledge on how genomic variation within bacterial species impacts phenotypic versatility. Because different environments have unique selection pressures, they drive divergent evolution. However, there is also parallel or convergent evolution of traits in independent bacterial isolates inhabiting similar environments. The application of tools to describe population-wide genomic diversity provides an opportunity to measure the predictability of genetic changes underlying adaptation. Here, we describe patterns of sequence variations in the core genome among 99 individual Pseudomonas aeruginosa clinical isolates and identified single-nucleotide polymorphisms that are the basis for branching of the phylogenetic tree. We also identified single-nucleotide polymorphisms that were acquired independently, in separate lineages, and not through inheritance from a common ancestor. Although our results demonstrate that the Pseudomonas aeruginosa core genome is highly conserved and in general, not subject to adaptive evolution, instances of parallel evolution will provide an opportunity to uncover genetic changes that underlie phenotypic diversity.
Topics: Adaptation, Physiological; Genome, Bacterial; Humans; Phenotype; Phylogeny; Polymorphism, Single Nucleotide; Pseudomonas aeruginosa
PubMed: 32196089
DOI: 10.1093/gbe/evaa059 -
Proceedings of the National Academy of... Oct 2022Pleiotropy may affect the maintenance of cooperation by limiting cheater mutants if such mutants lose other important traits. If pleiotropy limits cheaters, selection...
Pleiotropy may affect the maintenance of cooperation by limiting cheater mutants if such mutants lose other important traits. If pleiotropy limits cheaters, selection may favor cooperation loci that are more pleiotropic. However, the same should not be true for private loci with functions unrelated to cooperation. Pleiotropy in cooperative loci has mostly been studied with single loci and has not been measured on a wide scale or compared to a suitable set of control loci with private functions. I remedy this gap by comparing genomic measures of pleiotropy in previously identified cooperative and private loci in . I found that cooperative loci in tended to be more pleiotropic than private loci according to the number of protein-protein interactions, the number of gene ontology terms, and gene expression specificity. These results show that pleiotropy may be a general way to limit cheating and that cooperation may shape pleiotropy in the genome.
Topics: Genetic Pleiotropy; Mutation; Pseudomonas aeruginosa
PubMed: 36191234
DOI: 10.1073/pnas.2214827119 -
European Journal of Clinical... Dec 2021Modifying enzyme-CrpP and its variants reduced the MICs of fluoroquinolones in Pseudomonas aeruginosa. This study investigated the dissemination and functional...
Modifying enzyme-CrpP and its variants reduced the MICs of fluoroquinolones in Pseudomonas aeruginosa. This study investigated the dissemination and functional characteristics of CrpP-like in P. aeruginosa from China. The positive rate of crpP-like genes in 228 P. aeruginosa was 25.4% (58/228), and 6 new crpP-like genes were determined. Transformation experiments showed that CrpP-like had a low effect on CIP and LEV susceptibility. The genetic of crpP-positive was diverse. Furthermore, the mean expression level of crpP was no statistical difference between fluoroquinolone-susceptible and -resistant group (P > 0.05). CrpP-like may not play a significant role in fluoroquinolone resistance in P. aeruginosa.
Topics: Anti-Bacterial Agents; Bacterial Proteins; China; Ciprofloxacin; Humans; Microbial Sensitivity Tests; Pseudomonas Infections; Pseudomonas aeruginosa
PubMed: 34097170
DOI: 10.1007/s10096-021-04287-2 -
MBio Jun 2017Extracellular polysaccharides are compounds secreted by microorganisms into the surrounding environment, and they are important for surface attachment and maintaining...
Extracellular polysaccharides are compounds secreted by microorganisms into the surrounding environment, and they are important for surface attachment and maintaining structural integrity within biofilms. The social nature of many extracellular polysaccharides remains unclear, and it has been suggested that they could function as either cooperative public goods or as traits that provide a competitive advantage. Here, we empirically tested the cooperative nature of the PSL polysaccharide, which is crucial for the formation of biofilms in We show that (i) PSL is not metabolically costly to produce; (ii) PSL provides population-level benefits in biofilms, for both growth and antibiotic tolerance; (iii) the benefits of PSL production are social and are shared with other cells; (iv) the benefits of PSL production appear to be preferentially directed toward cells which produce PSL; (v) cells which do not produce PSL are unable to successfully exploit cells which produce PSL. Taken together, this suggests that PSL is a social but relatively nonexploitable trait and that growth within biofilms selects for PSL-producing strains, even when multiple strains are on a patch (low relatedness at the patch level). Many studies have shown that bacterial traits, such as siderophores and quorum sensing, are social in nature. This has led to an impression that secreted traits act as public goods, which are costly to produce but benefit both the producing cell and its surrounding neighbors. Theories and subsequent experiments have shown that such traits are exploitable by asocial cheats, but we show here that this does not always hold true. We demonstrate that the exopolysaccharide PSL provides social benefits to populations but that it is nonexploitable, because most of the fitness benefits accrue to PSL-producing cells. Our work builds on an increasing body of work showing that secreted traits can have both private and public benefits to cells.
Topics: Biofilms; Microbial Interactions; Polysaccharides, Bacterial; Pseudomonas aeruginosa
PubMed: 28634237
DOI: 10.1128/mBio.00374-17