RNA thermoswitches modulate Staphylococcus aureus adaptation to ambient temperatures.
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ABSTRACT:
SUBMITTER: Catalan-Moreno A
PROVIDER: S-EPMC8034633 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Staphylococcus aureus is a known cause of chronic biofilm infections that can reside on medical implants or host tissue. Recent studies have demonstrated an important role for proteinaceous material in the biofilm structure. The S. aureus genome encodes many secreted proteases, and there is growing evidence that these enzymes have self-cleavage properties that alter biofilm integrity. However, the specific contribution of each protease and mechanism of biofilm modulation is not clear. To address this issue, we utilized a sigma factor B (?sigB) mutant where protease activity results in a biofilm-negative phenotype, thereby creating a condition where the protease(s) responsible for the phenotype could be identified. Using a plasma-coated microtiter assay, biofilm formation was restored to the ?sigB mutant through the addition of the cysteine protease inhibitor E-64 or by using Staphostatin inhibitors that specifically target the extracellular cysteine proteases SspB and ScpA (called Staphopains). Through construction of gene deletion mutants, we determined that an sspB scpA double mutant restored ?sigB biofilm formation, and this recovery could be replicated in plasma-coated flow cell biofilms. Staphopain levels were also found to be decreased under biofilm-forming conditions, possibly allowing biofilm establishment. The treatment of S. aureus biofilms with purified SspB or ScpA enzyme inhibited their formation, and ScpA was also able to disperse an established biofilm. The antibiofilm properties of ScpA were conserved across S. aureus strain lineages. These findings suggest an underappreciated role of the SspB and ScpA cysteine proteases in modulating S. aureus biofilm architecture.
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Project description:The majority of Drosophila genes are expressed in a temperature-dependent manner, but the way in which small RNAs may contribute to this effect is completely unknown as we currently lack an idea of how small RNA transcriptomes change as a function of temperature. Applying high-throughput sequencing techniques complemented by quantitative real-time PCR experiments, we demonstrate that altered ambient temperature induces drastic but reversible changes in sequence composition and total abundance of both miRNA and piRNA populations. Further, mRNA sequencing reveals that the expression of miRNAs and their predicted target transcripts correlates inversely, suggesting that temperature-responsive miRNAs drive adaptation to different ambient temperatures on the transcriptome level. Finally, we demonstrate that shifts in temperature affect both primary and secondary piRNA pools, and the observed aberrations are consistent with altered expression levels of the involved Piwi-pathway factors. We further reason that enhanced ping-pong processing at 29°C is driven by dissolved RNA secondary structures at higher temperatures, uncovering target sites that are not accessible at low temperatures. Together, our results show that small RNAs are an important part of epigenetic regulatory mechanisms that ensure homeostasis and adaptation under fluctuating environmental conditions.
| S-EPMC5558905 | biostudies-literature
Project description:AimsTo understand the impact of storage temperature on recovery of Staphylococcus aureus on sampling swabs. Staphylococcus aureus is a common cause of skin and soft tissue infections, but also causes a variety of life-threatening diseases. With a large pool of asymptomatic carriers and transmission that can occur even through indirect contact, mitigation efforts have had limited success. Swab sampling, followed by culturing, is a cornerstone of epidemiological studies, however, S. aureus viability on swabs stored at different temperatures has not been characterized.Methods and resultsWe determined survival rates on swabs stored at five different temperatures. Samples stored at -70°C had no decay over time while samples stored at higher temperatures showed an exponential decay in viability. Mortality rates were greatest for swabs stored at 37°C. Survival at intermediate temperatures (-20 to 20·5°C) did not differ significantly, however, we observed more variation at higher temperatures.ConclusionsTo maximize recovery of S. aureus cells, samples should be stored at -70°C or processed for culturing without delay.Significance and impact of the studyEpidemiological studies of bacterial diseases are typically limited to determination of pathogen presence/absence, yet quantitative assessments of pathogen load and genetic diversity can provide insights into disease progression and severity, likelihood of transmission and adaptive evolutionary potential. For studies of S. aureus where time or access to a microbiology laboratory may delay culturing, deep freezing or timely culturing will maximize the degree to which sampling results reflect source status.
| S-EPMC8339145 | biostudies-literature
Project description:Staphylococcus aureus are globally disseminated among farmed chickens causing skeletal muscle infections, dermatitis, and septicaemia. The emergence of poultry-associated lineages has involved zoonotic transmission from humans to chickens but questions remain about the specific adaptations that promote proliferation of chicken pathogens. We characterized genetic variation in a population of genome-sequenced S. aureus isolates of poultry and human origin. Genealogical analysis identified a dominant poultry-associated sequence cluster within the CC5 clonal complex. Poultry and human CC5 isolates were significantly distinct from each other and more recombination events were detected in the poultry isolates. We identified 44 recombination events in 33 genes along the branch extending to the poultry-specific CC5 cluster, and 47 genes were found more often in CC5 poultry isolates compared with those from humans. Many of these gene sequences were common in chicken isolates from other clonal complexes suggesting horizontal gene transfer among poultry associated lineages. Consistent with functional predictions for putative poultry-associated genes, poultry isolates showed enhanced growth at 42?°C and greater erythrocyte lysis on chicken blood agar in comparison with human isolates. By combining phenotype information with evolutionary analyses of staphylococcal genomes, we provide evidence of adaptation, following a human-to-poultry host transition. This has important implications for the emergence and dissemination of new pathogenic clones associated with modern agriculture.
| S-EPMC5469444 | biostudies-literature
Project description:UnlabelledSkin is the most common site of Staphylococcus aureus infection. While most of these infections are self-limited, recurrent infections are common. Keratinocytes and recruited immune cells participate in skin defense against infection. We postulated that S. aureus is able to adapt to the milieu within human keratinocytes to avoid keratinocyte-mediated clearance. From a collection of S. aureus isolated from chronically infected patients with atopic dermatitis, we noted 22% had an agr mutant-like phenotype. Using several models of human skin infection, we demonstrate that toxin-deficient, agr mutants of methicillin-resistant S. aureus (MRSA) USA300 are able to persist within keratinocytes by stimulating autophagy and evading caspase-1 and inflammasome activation. MRSA infection induced keratinocyte autophagy, as evidenced by galectin-8 and LC3 accumulation. Autophagy promoted the degradation of inflammasome components and facilitated staphylococcal survival. The recovery of more than 58% agr or RNAIII mutants (P < 0.0001) of an inoculum of wild-type (WT) MRSA from within wortmannin-treated keratinocytes compared to control keratinocytes reflected the survival advantage for mutants no longer expressing agr-dependent toxins. Our results illustrate the dynamic interplay between S. aureus and keratinocytes that can result in the selection of mutants that have adapted specifically to evade keratinocyte-mediated clearance mechanisms.ImportanceHuman skin is a major site of staphylococcal infection, and keratinocytes actively participate in eradication of these pathogens. We demonstrate that methicillin-resistant Staphylococcus aureus (MRSA) is ingested by keratinocytes and activates caspase-1-mediated clearance through pyroptosis. Toxin-deficient MRSA mutants are selected within keratinocytes that fail to induce caspase-1 activity and keratinocyte-mediated clearance. These intracellular staphylococci induce autophagy that enhances their intracellular survival by diminishing inflammasome components. These findings suggest that S. aureus mutants, by exploiting autophagy, can persist within human keratinocytes.
| S-EPMC4453558 | biostudies-literature
Project description:Previous evaluation by different molecular and physiological assays of Staphylococcus aureus (S. aureus) responses to heat shock exposure yielded a still fragmentary view of the mechanisms determining bacterial survival or death at supra-physiological temperatures. This study analyzed diverse facets of S. aureus heat-shock adjustment by recording global transcriptomic and metabolic responses of bacterial cultures shifted for 10 min from 37oC to a sub-lethal (43oC) or eventually lethal (48oC) temperature. A relevant metabolic model of the combined action of specific stress response mechanisms with more general, energy-regulating metabolic pathways in heat-shocked S. aureus was designed. While S. aureus cultures shifted to 43oC or left at 37oC showed marginal differences in growth and survival rates, bacterial cultures exposed to 48oC showed a rapid growth arrest followed by a subsequent decline in viable counts. The most substantial heat shock-induced changes at both 43oC and 48oC occurred in transcript levels of HrcA- and CtsR-regulated genes, encoding classical chaperones DnaK and GroESL, and some Hsp100/Clp ATPases components, respectively. Other metabolic pathways up-regulated by S. aureus exposure at 48oC included genes encoding several enzymes coping with oxidative stress, and DNA damage, or/and impaired osmotic balance. Some major components of the pentose phosphate cycle and gluconeogenesis were also up-regulated, which reflected depletion of free glucose by bacterial cultures grown in Mueller-Hinton broth prior to heat shock. In contrast, most purine- and pyrimidine-synthesis pathway components and amino acyl-tRNA synthetases were down-regulated at 48oC, as well as arginine deiminase and major fermentative pathway components, such as alcohol, lactate and formate dehydrogenases. Despite the heat-induced, increased requirements for ATP-dependent macromolecular repair mechanisms combined with declining energy sources, intracellular ATP levels remained remarkably constant during heat shock. In conclusion, the sequential loss of replication and viability at 48oC cannot be explained by significant reductions in intracellular ATP levels, but may reflect ATP rerouting for macromolecular repair mechanisms and cell survival. Our metabolic model also suggests that heat-stressed S. aureus should down-regulate the production of potential, DNA-damaging reactive oxygen species that might result from electron transport-generated ATP, involving excessive levels of free heavy metals, in particular iron. Keywords: Staphylococcus aureus; heat shock; stress responses; transcriptomic profiling; physiological adjustment
2009-04-22 | GSE12920 | GEO
Project description:This project is intended to study the metabolic adaptation of Methicillin-Resistant Staphylococcus aureus (MRSA) to host immunity. Because of the nature of the samples RTI RCMRC worked with Dr. Anthony R. Richardson so that the samples would be extracted at the University of North Carolina at Chapel Hill under the condition that were optimized by RTI RCMRC for broad spectrum metabolomics analysis.
2017-09-10 | ST000453 | MetabolomicsWorkbench
Project description:BackgroundPrevious evaluation by different molecular and physiological assays of Staphylococcus aureus (S. aureus) responses to heat shock exposure yielded a still fragmentary view of the mechanisms determining bacterial survival or death at supra-physiological temperatures. This study analyzed diverse facets of S. aureus heat-shock adjustment by recording global transcriptomic and metabolic responses of bacterial cultures shifted for 10 min from 37 degrees C to a sub-lethal (43 degrees C) or eventually lethal (48 degrees C) temperature. A relevant metabolic model of the combined action of specific stress response mechanisms with more general, energy-regulating metabolic pathways in heat-shocked S. aureus is presented.ResultsWhile S. aureus cultures shifted to 43 degrees C or left at 37 degrees C showed marginal differences in growth and survival rates, bacterial cultures exposed to 48 degrees C showed a rapid growth arrest followed by a subsequent decline in viable counts. The most substantial heat shock-induced changes at both 43 degrees C and 48 degrees C occurred in transcript levels of HrcA- and CtsR-regulated genes, encoding classical chaperones DnaK and GroESL, and some Hsp100/Clp ATPases components, respectively. Other metabolic pathways up-regulated by S. aureus exposure at 48 degrees C included genes encoding several enzymes coping with oxidative stress, and DNA damage, or/and impaired osmotic balance. Some major components of the pentose phosphate cycle and gluconeogenesis were also up-regulated, which reflected depletion of free glucose by bacterial cultures grown in Mueller-Hinton broth prior to heat shock. In contrast, most purine- and pyrimidine-synthesis pathway components and amino acyl-tRNA synthetases were down-regulated at 48 degrees C, as well as arginine deiminase and major fermentative pathway components, such as alcohol, lactate and formate dehydrogenases. Despite the heat-induced, increased requirements for ATP-dependent macromolecular repair mechanisms combined with declining energy sources, intracellular ATP levels remained remarkably constant during heat shock.ConclusionThe sequential loss of replication and viability at 48 degrees C cannot be explained by significant reductions in intracellular ATP levels, but may reflect ATP rerouting for macromolecular repair mechanisms and cell survival. Our metabolic model also suggests that heat-stressed S. aureus should down-regulate the production of potential, DNA-damaging reactive oxygen species that might result from electron transport-generated ATP, involving excessive levels of free heavy metals, in particular iron.
| S-EPMC2687450 | biostudies-literature
Project description:Molecular analysis of RNA through hybridization with sequence-specific probes is challenging due to the intrinsic ability of RNA molecules to form stable secondary and tertiary structures. To overcome the energy barrier toward the probe-RNA complex formation, the probes are made of artificial nucleotides, which are more expensive than their natural counterparts and may still be inefficient. Here, we propose the use of a multicomponent probe based on an RNA-cleaving deoxyribozyme for the analysis of highly structured RNA targets. Efficient interrogation of two native RNA from Saccharomyces cerevisiae-a transfer RNA (tRNA) and 18S ribosomal RNA (rRNA)-was achieved at ambient temperature. We achieved detection limits of tRNA down to ∼0.3 nM, which is two orders of magnitude lower than that previously reported for molecular beacon probes. Importantly, no probe annealing to the target was required, with the hybridization assay performed at 37°C. Excess of nonspecific targets did not compromise the performance of the probe, and high interrogation efficiency was maintained by the probes even in complex matrices, such as cell lysate. A linear dynamic range of 0.3-150 nM tRNA was demonstrated. The probe can be adapted for differentiation of a single mismatch in the tRNA-probe complex. Therefore, this study opens a venue toward highly selective, sensitive, robust, and inexpensive assays for the interrogation of biological RNA.
| S-EPMC7668264 | biostudies-literature
Project description:This work aimed to investigate the metabolic changes of epithelial cell metabolism during S. aureus infection. We revealed that persistent S. aureus survived in epithelial cells by modulating the cellular pathways of one carbon pool by folate. These results highlight the persistence mechanisms of S. aureus survived in epithelial cells by regulation of cellular metabolism, shedding light on the development of intervention strategies to combat S. aureus associated infections.
2021-05-12 | GSE174235 | GEO