T2SS-peptidase XcpA associated with LasR evolutional phenotypic variations provides a fitness advantage to Pseudomonas aeruginosa PAO1
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ABSTRACT:
SUBMITTER: Cheng M
PROVIDER: S-EPMC10637944 | biostudies-literature | 2023 Jan
REPOSITORIES: biostudies-literature
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Project description:Sulfane sulfur, such as inorganic and organic polysulfide (HSn- and RSn-, n > 2), is a common cellular component, produced either from hydrogen sulfide oxidation or cysteine metabolism. In Pseudomonas aeruginosa PAO1, LasR is a quorum sensing master regulator. After binding its autoinducer, LasR binds to its target DNA to activate the transcription of a suite of genes, including virulence factors. Herein, we report that the production of hydrogen sulfide and sulfane sulfur were positively correlated in P. aeruginosa PAO1, and sulfane sulfur was able to modify LasR, which generated Cys188 persulfide and trisulfide and produced a pentasulfur link between Cys201 and Cys203. The modifications did not affect LasR binding to its target DNA site, but made it several-fold more effective than unmodified LasR in activating transcription in both in vitro and in vivo assays. On the contrary, H2O2 inactivates LasR via producing a disulfide bond between Cys201 and Cys203. P. aeruginosa PAO1 had a high cellular sulfane sulfur and high LasR activity in the mid log phase and early stationary phase, but a low sulfane sulfur and low LasR activity in the declination phase. Thus, sulfane sulfur is a new signaling factor in the bacterium, adding another level of control over LasR-mediated quorum sensing and turning down the activity in old cells.
| S-EPMC8469610 | biostudies-literature
Project description:Cross-feeding of metabolites between subpopulations can affect cell phenotypes and population-level behaviors. In chronic Pseudomonas aeruginosa lung infections, subpopulations with loss-of-function (LOF) mutations in the lasR gene are common. LasR, a transcription factor often described for its role in virulence factor expression, also impacts metabolism, which, in turn, affects interactions between LasR+ and LasR- genotypes. Prior transcriptomic analyses suggested that citrate, a metabolite secreted by many cell types, induces virulence factor production when both genotypes are together. An unbiased analysis of the intracellular metabolome revealed broad differences including higher levels of citrate in lasR LOF mutants. Citrate consumption by LasR- strains required the CbrAB two-component system, which relieves carbon catabolite repression and is elevated in lasR LOF mutants. Within mixed communities, the citrate-responsive two-component system TctED and its gene targets OpdH (porin) and TctABC (citrate transporter) that are predicted to be under catabolite repression control were induced and required for enhanced RhlR/I-dependent signaling, pyocyanin production, and fitness of LasR- strains. Citrate uptake by LasR- strains markedly increased pyocyanin production in co-culture with Staphylococcus aureus, which also secretes citrate and frequently co-infects with P. aeruginosa. This citrate-induced restoration of virulence factor production by LasR- strains in communities with diverse species or genotypes may offer an explanation for the contrast observed between the markedly deficient virulence factor production of LasR- strains in monocultures and their association with the most severe forms of cystic fibrosis lung infections. These studies highlight the impact of secreted metabolites in mixed microbial communities.IMPORTANCECross-feeding of metabolites can change community composition, structure, and function. Here, we unravel a cross-feeding mechanism between frequently co-observed isolate genotypes in chronic Pseudomonas aeruginosa lung infections. We illustrate an example of how clonally derived diversity in a microbial communication system enables intra- and inter-species cross-feeding. Citrate, a metabolite released by many cells including P. aeruginosa and Staphylococcus aureus, was differentially consumed between genotypes. Since these two pathogens frequently co-occur in the most severe cystic fibrosis lung infections, the cross-feeding-induced virulence factor expression and fitness described here between diverse genotypes exemplify how co-occurrence can facilitate the development of worse disease outcomes.
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Project description:Horizontal gene transfer (HGT) mediated by the spread of plasmids fuels evolution in prokaryotes. Although plasmids provide bacteria with new adaptive genes, they also produce physiological alterations that often translate into a reduction in bacterial fitness. The fitness costs associated with plasmids represent an important limit to plasmid maintenance in bacterial communities, but their molecular origins remain largely unknown. In this work, we combine phenomics, transcriptomics and metabolomics to study the fitness effects produced by a collection of diverse plasmids in the opportunistic pathogen Pseudomonas aeruginosa PAO1. Using this approach, we scan the physiological changes imposed by plasmids and test the generality of some main mechanisms that have been proposed to explain the cost of HGT, including increased biosynthetic burden, reduced translational efficiency, and impaired chromosomal replication. Our results suggest that the fitness effects of plasmids have a complex origin, since none of these mechanisms could individually provide a general explanation for the cost of plasmid carriage. Interestingly, our results also showed that plasmids alter the expression of a common set of metabolic genes in PAO1, and produce convergent changes in host cell metabolism. These surprising results suggest that there is a common metabolic response to plasmids in P. aeruginosa PAO1.
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Project description:Chirality in shape and motility can evolve rapidly in microbes and cancer cells. To determine how chirality affects cell fitness, we developed a model of chiral growth in compact aggregates such as microbial colonies and solid tumors. Our model recapitulates previous experimental findings and shows that mutant cells can invade by increasing their chirality or switching their handedness. The invasion results either in a takeover or stable coexistence between the mutant and the ancestor depending on their relative chirality. For large chiralities, the coexistence is accompanied by strong intermixing between the cells, while spatial segregation occurs otherwise. We show that the competition within the aggregate is mediated by bulges in regions where the cells with different chiralities meet. The two-way coupling between aggregate shape and natural selection is described by the chiral Kardar-Parisi-Zhang equation coupled to the Burgers' equation with multiplicative noise. We solve for the key features of this theory to explain the origin of selection on chirality. Overall, our work suggests that chirality could be an important ecological trait that mediates competition, invasion, and spatial structure in cellular populations.
| S-EPMC6307711 | biostudies-literature
Project description:Pseudomonas aeruginosa strains with loss-of-function mutations in the transcription factor LasR are frequently encountered in the clinic and the environment. Among the characteristics common to LasR-defective (LasR-) strains is increased activity of the transcription factor Anr, relative to their LasR+ counterparts, in low-oxygen conditions. One of the Anr-regulated genes found to be highly induced in LasR- strains was PA14_42860 (PA1673), which we named mhr for microoxic hemerythrin. Purified P. aeruginosa Mhr protein contained the predicted di-iron center and bound molecular oxygen with an apparent K d of ∼1 µM. Both Anr and Mhr were necessary for fitness in lasR+ and lasR mutant strains in colony biofilms grown in microoxic conditions, and the effects were more striking in the lasR mutant. Among genes in the Anr regulon, mhr was most closely coregulated with the Anr-controlled high-affinity cytochrome c oxidase genes. In the absence of high-affinity cytochrome c oxidases, deletion of mhr no longer caused a fitness disadvantage, suggesting that Mhr works in concert with microoxic respiration. We demonstrate that Anr and Mhr contribute to LasR- strain fitness even in biofilms grown in normoxic conditions. Furthermore, metabolomics data indicate that, in a lasR mutant, expression of Anr-regulated mhr leads to differences in metabolism in cells grown on lysogeny broth or artificial sputum medium. We propose that increased Anr activity leads to higher levels of the oxygen-binding protein Mhr, which confers an advantage to lasR mutants in microoxic conditions.
| S-EPMC7022198 | biostudies-literature
Project description:The Pseudomonas aeruginosa strain PAO1 has routinely been used as a laboratory model for quorum sensing (QS). However, the microevolution of P. aeruginosa laboratory strains resulting in genetic and phenotypic variations have caused inconsistencies in QS research. To investigate the underlying causes of these variations, we analyzed 5 Pseudomonas aeruginosa PAO1 sublines from our laboratory using a combination of phenotypic characterization, high throughput genome sequencing, and bioinformatic analysis. The major phenotypic variations among the sublines spanned across the levels of QS signals and virulence factors such as pyocyanin and elastase. Furthermore, the sublines exhibited distinct variations in motility and biofilm formation. Most of the phenotypic variations were mapped to mutations in the lasR and mexT, which are key components of the QS circuit. By introducing these mutations in the subline PAO1-E, which is devoid of such mutations, we confirmed their influence on QS, virulence, motility, and biofilm formation. The findings further highlight a possible divergent regulatory mechanism between the LasR and MexT in the P. aeruginosa. The results of our study reveal the effects of microevolution on the reproducibility of most research data from QS studies and further highlight mexT as a key component of the QS circuit of P. aeruginosa.
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Project description:Pseudomonas aeruginosa is a prevalent opportunistic pathogen that causes fatal infections in immunocompromised individuals. Quorum sensing (QS) is a cell-to-cell communication process that controls virulence gene expression and biofilm formation in P. aeruginosa. Here, the QS systems and the relevant virulence traits in clinical P. aeruginosa isolates were characterized. Eleven out of the ninety-four P. aeruginosa isolates exhibited a biofilm-deficient phenotype. Two biofilm-deficient isolates, one from blood and the one from pleural effusion, appeared to carry a same mutation in lasR. These two isolates differed in the ability to produce QS-regulated virulence factors, but contained the same functionally deficient LasR with the truncated C-terminal domains and belonged to the same multilocus sequence type (ST227). Chromosomal lasR complementation in these lasR mutants verified that lasR inactivation was the sole cause of las deficiency. LasR was not absolutely required for rhl signal in these lasR mutants, suggesting the presence of lasR-independent QS systems. We provided evidence that the virulence gene expression are not regulated in the same manner in these isolates. These results support the hypothesis that conventional QS hierarchy can be smashed by naturally occurring lasR mutation in clinical P. aeruginosa isolates and that complex QS hierarchy may play a role in maintaining infection of this opportunistic pathogen.
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Project description:Uropathogenic E. coli (UPEC) is the dominant cause of urinary tract infections, clinically described as cystitis. UPEC express CUP pili, which are extracellular fibers tipped with adhesins that bind mucosal surfaces of the urinary tract. Here we identify the role of the F9/Yde/Fml pilus for UPEC persistence in the inflamed urothelium. The Fml adhesin FmlH binds galactose β1-3 N-acetylgalactosamine found in core-1 and -2 O-glycans. Deletion of fmlH had no effect on UPEC virulence in an acute mouse model of cystitis. However, FmlH provided a fitness advantage during chronic cystitis, which is manifested as persistent bacteriuria, high bladder bacterial burdens, and chronic inflammation. In situ binding confirmed that FmlH bound avidly to the inflamed, but not the naive bladder. In accordance with its pathogenic profile, vaccination with FmlH significantly protected mice from chronic cystitis. Thus, UPEC employ separate CUP pili to adapt to the rapidly changing niche during bladder infection.
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Project description:Antagonism of quorum sensing represents a promising new antivirulence approach for the treatment of bacterial infection. The development of a novel series of non-natural irreversible antagonists of P. aeruginosa LasR is described. The lead compounds identified (25 and 28) display potent LasR antagonist activity and inhibit expression of the P. aeruginosa virulence factors pyocyanin and biofilm formation in PAO1 and PA14.
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Project description:Pseudomonas aeruginosa PAO1 is the most commonly used strain for research on this ubiquitous and metabolically versatile opportunistic pathogen. Strain PAO1, a derivative of the original Australian PAO isolate, has been distributed worldwide to laboratories and strain collections. Over decades discordant phenotypes of PAO1 sublines have emerged. Taking the existing PAO1-UW genome sequence (named after the University of Washington, which led the sequencing project) as a blueprint, the genome sequences of reference strains MPAO1 and PAO1-DSM (stored at the German Collection for Microorganisms and Cell Cultures [DSMZ]) were resolved by physical mapping and deep short read sequencing-by-synthesis. MPAO1 has been the source of near-saturation libraries of transposon insertion mutants, and PAO1-DSM is identical in its SpeI-DpnI restriction map with the original isolate. The major genomic differences of MPAO1 and PAO1-DSM in comparison to PAO1-UW are the lack of a large inversion, a duplication of a mobile 12-kb prophage region carrying a distinct integrase and protein phosphatases or kinases, deletions of 3 to 1,006 bp in size, and at least 39 single-nucleotide substitutions, 17 of which affect protein sequences. The PAO1 sublines differed in their ability to cope with nutrient limitation and their virulence in an acute murine airway infection model. Subline PAO1-DSM outnumbered the two other sublines in late stationary growth phase. In conclusion, P. aeruginosa PAO1 shows an ongoing microevolution of genotype and phenotype that jeopardizes the reproducibility of research. High-throughput genome resequencing will resolve more cases and could become a proper quality control for strain collections.
| S-EPMC2812968 | biostudies-literature