Project description:Salmonella enterica serovar Typhimurium is known to synthesize and respond to the cell signaling molecule, autoinducer-2 (AI-2). The luxS gene is involved in the synthesis of AI-2. We have previously shown that luxS controls a variety of bacterial processes in S. Typhimurium. In this study we identified the genes regulated by AI-2 in the Cell-Free supernatant of S. Typhimurium using mRNA samples from isogenic luxS gene mutant of S. Typhimurium strain 87-26254 grown in LB media in the presence of S. Typhimurium wild type CFS / absence AI-2 (mutant CFS of S. Typhimurium). In the presence of AI-2 in CFS, 758 genes were significantly regulated. Interstingly, AI-2 in CFS caused the down-regulation of 39 genes in Salmonella Pathogenicity Island-1 (SPI-1).
Project description:We describe how searching chimeric spectra with post-processing including MS²PIP-derived features aids the identification of hypothetical and unannotated proteins. We apply our workflow to the well-characterized human bacterial pathogen Salmonella enterica serovar Typhimurium (S. Typhimurium) and validate novel protein-coding regions with by ribo-seq translation evidence. We further elaborate how riboproteogenomics is instrumental for reannotating ORFs and the discovery of novel ORFs across bacteria.
Project description:Salmonella enterica serotype Typhimurium produces a variety of fimbrial appendages, among which the type 1 fimbriae is the most common type. In vitro static broth culture favors S. Typhimurium to produce type 1 fimbriae, while solid agar inhibits its expression. A transposon inserted in the stbC gene, which would encode an usher protein for Stb fimbriae of a non-flagellar S. Typhimurium LB5010 strain, conferred it to agglutinate yeast cells on both cultures, and was mannose-sensitive. Reverse transcription polymerase chain reaction (RT-PCR) revealed that the expression of the fimbrial major subunit gene fimA, and fimZ, a positive regulator gene of fimA, were both increased in the stbC mutant strain when grown on LB agar; fimW, a repressor gene of fimA, exhibited lower expression. Flagella were observed in the stbC mutant and this phenotype was correlated with the motile phenotype detected by MSRV agar medium and reaction with flagella antiserum. Microarray data and RT-PCR also indicated that the expression of three genes, motA, motB, and cheM, was enhanced in the stbC mutant. The S. Typhimurium stbC mutant was resistant to a variety of antibiotics, consistent with the finding that expression of yhcQ and ramA, two genes involved in multidrug resistance, was enhanced. A complementation test revealed that transforming a recombinant plasmid possessing the coding sequence of the stbC gene restored the mannose-sensitive agglutination phenotype to the stbC mutant much as that in the parental S. Typhimurium LB5010 strain, indicating the possibility of an interplay of different fimbrial systems in coordinating their expression. Key Words: Salmonella enterica serotype Typhimurium, fimbriae, type 1 fimbriae, stbC, transposon, multidrug resistant, flagella
Project description:Transcriptional profiling of log and stationary phases of S. Typhimurium, comparing untreated controls with cortisol-treated samples.
Project description:In this study, we have defined the NsrR regulon in Salmonella enterica sv. Typhimurium 14028s using a transcriptional microarray. Wild-type and nsrR mutant S. Typhimurium were grown aerobically to early log-phase (OD600~0.5) at 37C in LB medium. Total RNA was isolated from three independent cultures of both strains and interrogated on a PCR product array representing almost all ORFs.