Project description:Methicillin-resistant Staphylococcus aureus (MRSA) infections result in more than 200,000 hospitalizations and 10,000 deaths in the United States each year and remain an important medical challenge. To better understand the transcriptome of Staphylococcus aureus USA300 NRS384, a community-acquired MRSA strain, we have conducted an RNA-Seq experiment on WT samples.
Project description:Methicillin-resistant Staphylococcus aureus (MRSA) infections result in more than 200,000 hospitalizations and 10,000 deaths in the United States each year and remain an important medical challenge. A key factor of S. aureus pathogenesis is the production of virulence proteins that are secreted into the extracellular matrix damaging host tissues and forming abscesses that may serve as replicative niches for the bacteria. We recently discovered that host-derived cis-unsaturated fatty acids activate the transcription and translation of EsxA, a protein that plays a central role in abscess formation in clinically relevant MRSA strains. Additionally, we discovered that fatty acid stimulation of EsxA is dependent on fakA, a gene that encodes a protein responsible for the incorporation of exogenous fatty acids into the S. aureus phospholipid membrane. In order to gain a comprehensive understanding of host-fatty-acid-sensing in S. aureus, we performed RNA-Seq analysis on WT Staphylococcus aureus USA300 NRS384, a community-acquired MRSA strain, in the presence and absence of 10μM linoleic acid.
Project description:Methicillin-resistant Staphylococcus aureus is one of the major causative agents associated to infections with a high morbidity and mortality in hospitals worldwide. In previous studies, we reported that lignan 3'-demethoxy-6-O-demethylisoguaiacin isolated and characterized from Larrea tridentata showed the best activity towards methicillin-resistant S. aureus. Understanding of mechanism of action of drugs allows design drugs in a better way. Therefore, we employed microarray to obtain gene expression profile of methicillin-resistant S. aureus after exposure to 3'-demethoxy-6-O-demethylisoguaiacin. The results showed that lignan had an effect on cell membrane affecting proteins of the ATP-binding cassette (ABC) transport system causing bacteria death.
Project description:Staphylococcus aureus is a major pathogen of healthcare settings with a high rate of morbidity and mortality. S. aureus has also emerged as a serious threat in healthy individuals in the community. Increasingly, antibiotic resistant S. aureus strains, particularly methicillin resistant S. aureus (MRSA), are causing these community-acquired infections (CA-MRSA). Because of the rising incidence of antibiotic resistance, including resistance to “last resort” antibiotics, development of prophylactic vaccines for S. aureus is considered a high priority. A complete, accurate characterization of the transcriptome of the host during different types of infection would expedite S. aureus vaccine development by identifying antigens that would be optimal vaccine targets. RNA-seq (deep-sequencing of cDNA) provides an unbiased method to comprehensively and systematically define the transcriptome (the complete set of transcribed regions in a genome) of an organism in a manner that is significantly more sensitive than microarray hybridization approaches. We propose a comprehensive characterization of the host transcriptome in two different murine models of infection (systemic infection and skin and soft tissue infection (SSTI)). We believe that this research will provide insight into potential vaccine targets that are expressed at high levels in both types of infection. We also wish to determine what mouse genes are up- or down-regulated during the course of these infections in order to better characterize the host-pathogen interaction. This description of the in vivo transcriptome will give novel insight into how the host senses and responds to infection with S. aureus in different infection types, and how the host tissue responds to bacterial invasion.
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.
Project description:Screening of various bisquaternary bisnaphthalimides against a variety of human pathogens revealed one compound, designated MT02, with strong inhibitory effects against gram-positive bacteria. The minimal inhibitory concentrations ranged from 0.31 µg/ml against community-acquired methicillin resistant Staphylococcus aureus (MRSA) strain USA300 to 20 µg/ml against Streptococcus pneumonia. DNA-microarray studies generated a transcriptional signature characterized by a strong increase of genes involved in DNA-metabolism, DNA-replication, SOS-response and transport of positively charged compounds. Radioactive whole cell labeling experiments indicated a strong impact of MT02 on bacterial DNA-replication. Furthermore, surface plasmon resonance and gel retardation experiments demonstrated direct binding of MT02 to DNA in a concentration dependent, reversible and sequence-unspecific manner. The data presented suggest that the bisquaternary bisnaphthalimide MT02 exerts anti-gram-positive activity by binding to DNA and thereby prohibiting appropriate DNA-replication. WT strain exposed to MT02 for 60 minutes in rich medium
Project description:Screening of various bisquaternary bisnaphthalimides against a variety of human pathogens revealed one compound, designated MT02, with strong inhibitory effects against gram-positive bacteria. The minimal inhibitory concentrations ranged from 0.31 µg/ml against community-acquired methicillin resistant Staphylococcus aureus (MRSA) strain USA300 to 20 µg/ml against Streptococcus pneumonia. DNA-microarray studies generated a transcriptional signature characterized by a strong increase of genes involved in DNA-metabolism, DNA-replication, SOS-response and transport of positively charged compounds. Radioactive whole cell labeling experiments indicated a strong impact of MT02 on bacterial DNA-replication. Furthermore, surface plasmon resonance and gel retardation experiments demonstrated direct binding of MT02 to DNA in a concentration dependent, reversible and sequence-unspecific manner. The data presented suggest that the bisquaternary bisnaphthalimide MT02 exerts anti-gram-positive activity by binding to DNA and thereby prohibiting appropriate DNA-replication.
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.