Staphylococcus aureus
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA370921 | ENA |
REPOSITORIES: ENA
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Project description:Phage-derived lytic proteins are a promising alternative to conventional antimicrobials. One of their most interesting properties is that they do not readily select for resistant strains, which is likely due to the fact that their targets are essential for the viability of the bacterial cell. Moreover, genetic engineering allows the design of new "tailor-made" proteins that may exhibit improved antibacterial properties. One example of this is the chimeric protein CHAPSH3b, which consists of a catalytic domain from the virion-associated peptidoglycan (PG) hydrolase of phage vB_SauS-phiIPLA88 (HydH5) and the cell wall binding domain of lysostaphin. CHAPSH3b had previously shown the ability to kill S. aureus cells. Here, we demonstrate that this lytic protein also has potential for the control of biofilm-embedded S. aureus cells. Additionally, subinhibitory doses of CHAPSH3b can decrease biofilm formation by some S. aureus strains. Transcriptional analysis revealed that exposure of S. aureus cells to this enzyme leads to the downregulation of several genes coding for bacterial autolysins. One of these proteins, namely the major autolysin AtlA, is known to participate in staphylococcal biofilm development. Interestingly, an atl mutant strain did not display inhibition of biofilm development when grown at subinhibitory concentrations of CHAPSH3b, contrary to the observations made for the parental and complemented strains. Also, deletion of atl led to low-level resistance to CHAPSH3b and endolysin LysH5. Overall, our results reveal new aspects that should be considered when designing new phage-derived lytic proteins aimed for antimicrobial applications.
2017-03-16 | GSE94512 | GEO
Project description:gltS is glutamate transporter. We examined the role of gltS in staphylococcus aureus biofilm formation.
2022-11-07 | GSE216751 | GEO
Project description:Staphylococcus aureus is a Gram-positive human pathogen causing a variety of human diseases in both hospital and community settings. This bacterium is so closely associated with prophages that it is rare to find S. aureus isolates without prophages. Two phages are known to be important for staphylococcal virulence: the beta-hemolysin (hlb) converting phage and the Panton-Valentine Leukocidin (PVL) converting phage. The hlb-converting phage is found in more than 90% of clinical isolates of S. aureus. This phage produces exotoxins and immune modulatory molecules, which inhibit human innate immune responses. The PVL-converting phage produces the two-component exotoxin PVL, which can kill human leucocytes. This phage is wide-spread among community-associated methicillin resistant S. aureus (CA-MRSA). It also shows strong association with soft tissue infections and necrotizing pneumonia. Several lines of evidence suggest that staphylococcal prophages increase bacterial virulence not only by providing virulence factors but also by altering bacterial gene expression: 1) Transposon insertion into prophage regulatory genes, but not into the genes of virulence factors, reduced S. aureus killing of Caenorhabditis elegans.; 2) Although the toxins and immune modulatory molecules encoded by the hlb- converting phages do not function in the murine system, deletion of ϕNM3, the hlb-converting phage in S. aureus Newman, reduced staphylococcal virulence in the murine abscess formation model. 3) In a preliminary microarray experiment, prophages in S. aureus Newman altered the expression of more than 300 genes. In this research proposal, using microarray and high-throughput quantitative RT-PCR (qRT-PCR) technologies, we will identify the effects of the two important staphylococcal phages on the gene expression of S. aureus in both in vitro and in vivo conditions. This project is intended to be completed within one year. All the data – microarray, qRT-PCR and all the primer sequences- will be made available to public 6 month after completion. Data from this project will help us to understand the role of prophages in the S. aureus pathogenesis and can lead to development of a strategy to interfere with the pathogenesis process. Following strains were grown in TSA broth: Staphylococcus aureus USA300 (reference) Staphylococcus aureus USA300 with deletion of ϕSa2usa (Query) Staphylococcus aureus USA300 with deletion of ϕSa3usa (Query) Staphylococcus aureus USA300 Prophage-free mutant (Query) Staphylococcus aureus USA300 Prophage-free mutant lysogenized with ϕSa2mw (Query) Staphylococcus aureus USA300 Prophage-free mutant lysogenized with ϕSa3usa (Query) strain: Staphylococcus aureus USA300 Prophage-free mutant lysogenized with both ϕSa2mw and ϕSa3usa (Query) RNA samples were harvested at early log, midlog and stationary phase.Samples were hybridized on aminosilane coated slides with 70-mer oligos.
2011-02-28 | E-GEOD-26623 | biostudies-arrayexpress
Project description:In this work we have demonstrated increased mutability of Staphylococcus aureus and S. epidermidis in biofilms and have explored the mechanisms underlying the enhanced mutability. A novel static biofilm model, utilising cellulose filter disks, was developed to support the formation of mature biofilms with sufficiently high cell densities to permit determination of mutation frequencies. The mutability of biofilm cultures increased up to 60 fold and 4 fold for S. aureus and S. epidermidis, respectively, compared with planktonic cultures. Incorporation of antioxidants into S. aureus biofilms reduced mutation frequencies, indicating that increased oxidative stress underlies increased mutability in the biofilm. Transcriptional profiling revealed upregulation of the superoxide dismutase gene, sodA, in early biofilm cultures, also suggesting enhanced oxidative stress in these cultures. However, loss of the genes encoding superoxide dismutases or peroxidases did not specifically exacerabate biofilm mutability. In S. aureus SH1000, hydrogen peroxide was found to contribute to biofilm mutability. Three growth conditions (18 hr planktonic growth, 48 hr biofilm growth and 144 biofilm growth) of which there are three biological replicates of each
2012-03-01 | E-GEOD-35837 | biostudies-arrayexpress
Project description:Staphylococcus aureus (S. aureus) is one of the most important pathogens in humans and animals. The formation of S. aureus biofilm is considered an important mechanism of antimicrobial resistance. Therefore, finding effective drugs against the biofilm produced by S. aureus has been a high priority. Licochalcone A, a natural plant product, was reported to have antibacterial activities and showed good activity against all 21 tested strains of S. aureus biofilm and planktonic cells. To detect the possible molecular mechanism of Licochalcone A against S. aureus biofillm or planktonic cells, Affymetrix GeneChips were used to determine the global comparative transcription of S. aureus biofilm and planktonic cells triggered by treatment with sub-bactericidal and sub-inhibitory concentrations of Licochalcone A, respectively. Staphylococcus aureus planktonic cells and biofilm were exposed for 60 minutes to Licochalcone A at concentration of 2 M-NM-<g/ml (1/2M-CM-^W MIC) and 64 M-NM-<g/ml (4M-CM-^W MIBC), respectively. 4 samples including 4 control samples are analyzed.
2014-07-01 | E-GEOD-58938 | biostudies-arrayexpress
Project description:In this work we have demonstrated increased mutability of Staphylococcus aureus and S. epidermidis in biofilms and have explored the mechanisms underlying the enhanced mutability. A novel static biofilm model, utilising cellulose filter disks, was developed to support the formation of mature biofilms with sufficiently high cell densities to permit determination of mutation frequencies. The mutability of biofilm cultures increased up to 60 fold and 4 fold for S. aureus and S. epidermidis, respectively, compared with planktonic cultures. Incorporation of antioxidants into S. aureus biofilms reduced mutation frequencies, indicating that increased oxidative stress underlies increased mutability in the biofilm. Transcriptional profiling revealed upregulation of the superoxide dismutase gene, sodA, in early biofilm cultures, also suggesting enhanced oxidative stress in these cultures. However, loss of the genes encoding superoxide dismutases or peroxidases did not specifically exacerabate biofilm mutability. In S. aureus SH1000, hydrogen peroxide was found to contribute to biofilm mutability.
2012-03-01 | GSE35837 | GEO
Project description:Staphylococcus aureus is a Gram-positive human pathogen causing a variety of human diseases in both hospital and community settings. This bacterium is so closely associated with prophages that it is rare to find S. aureus isolates without prophages. Two phages are known to be important for staphylococcal virulence: the beta-hemolysin (hlb) converting phage and the Panton-Valentine Leukocidin (PVL) converting phage. The hlb-converting phage is found in more than 90% of clinical isolates of S. aureus. This phage produces exotoxins and immune modulatory molecules, which inhibit human innate immune responses. The PVL-converting phage produces the two-component exotoxin PVL, which can kill human leucocytes. This phage is wide-spread among community-associated methicillin resistant S. aureus (CA-MRSA). It also shows strong association with soft tissue infections and necrotizing pneumonia. Several lines of evidence suggest that staphylococcal prophages increase bacterial virulence not only by providing virulence factors but also by altering bacterial gene expression: 1) Transposon insertion into prophage regulatory genes, but not into the genes of virulence factors, reduced S. aureus killing of Caenorhabditis elegans.; 2) Although the toxins and immune modulatory molecules encoded by the hlb- converting phages do not function in the murine system, deletion of NM3, the hlb-converting phage in S. aureus Newman, reduced staphylococcal virulence in the murine abscess formation model. 3) In a preliminary microarray experiment, prophages in S. aureus Newman altered the expression of more than 300 genes. In this research proposal, using microarray and high-throughput quantitative RT-PCR (qRT-PCR) technologies, we will identify the effects of the two important staphylococcal phages on the gene expression of S. aureus in both in vitro and in vivo conditions. This project is intended to be completed within one year. All the data – microarray, qRT-PCR and all the primer sequences- will be made available to public 6 month after completion. Data from this project will help us to understand the role of prophages in the S. aureus pathogenesis and can lead to development of a strategy to interfere with the pathogenesis process. Staphylococcus aureus subsp.aureus strain Newman (reference) and Staphylococcus aureus subsp.aureus strain Newman yhcR knockout(query) were grown in TSA broth.Samples were grown under aerobic and anaerobic conditions and RNA samples harvested at mid log, stationary, and log phases.Samples were hybridized on aminosilane coated slides with 70-mer oligos.
2011-12-31 | E-GEOD-26585 | biostudies-arrayexpress
Project description:Staphylococcus aureus (S. aureus) is one of the most important pathogens in humans and animals. The formation of S. aureus biofilm is considered an important mechanism of antimicrobial resistance. Therefore, finding effective drugs against the biofilm produced by S. aureus has been a high priority. Licochalcone A, a natural plant product, was reported to have antibacterial activities and showed good activity against all 21 tested strains of S. aureus biofilm and planktonic cells. To detect the possible molecular mechanism of Licochalcone A against S. aureus biofillm or planktonic cells, Affymetrix GeneChips were used to determine the global comparative transcription of S. aureus biofilm and planktonic cells triggered by treatment with sub-bactericidal and sub-inhibitory concentrations of Licochalcone A, respectively.
2014-07-01 | GSE58938 | GEO
Project description:The SaeRS two-component regulatory system of Staphylococcus aureus is known to affect the expression of many genes. The SaeS protein is the histidine kinase responsible for phosphorylation of the response regulator SaeR. In S. aureus Newman, the sae system is constitutively expressed due to a point mutation in saeS, relative to other S. aureus strains, which results in substitution of proline for leucine at amino acid 18. Strain Newman is unable to form a robust biofilm and we report here that the biofilm-deficient phenotype is due to the saeSP allele. Replacement of the Newman saeSP with saeSL, or deletion of saeRS, resulted in a biofilm-proficient phenotype. Newman culture supernatants were observed to inhibit biofilm formation by other S. aureus strains, but did not affect biofilm formation by S. epidermidis. Culture supernatants of Newman saeSL or Newman ΔsaeRS had no significant effect on biofilm formation. The inhibitory factor was inactivated by incubation with proteinase K, but survived heating, indicating that the inhibitory protein is heat-stable. The inhibitory protein was found to affect the attachment step in biofilm formation, but had no effect on preformed biofilms. Replacement of saeSL with saeSP in the biofilm-proficient S. aureus USA300 FPR3757 resulted in the loss of biofilm formation. Culture supernatants of USA300 FPR3757 saeSP, did not inhibit biofilm formation by other staphylococci, suggesting that the inhibitory factor is produced but not secreted in the mutant strain. A number of biochemical methods were utilized to isolate the inhibitory protein. Although a number of candidate proteins were identified, none were found to be the actual inhibitor. In an effort to reduce the number of potential inhibitory genes, RNA-Seq analyses were done with wild-type strain Newman and the saeSL and ΔsaeRS mutants. RNA-Seq results indicated that sae regulates many genes that may affect biofilm formation by Newman.
2015-04-30 | GSE65827 | GEO