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Salmonella Typhimurium stbC mutant

ABSTRACT: 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

ORGANISM(S): Salmonella enterica subsp. enterica serovar Typhimurium str. LT2

PROVIDER: GSE34685 | GEO | 2011/12/25

SECONDARY ACCESSION(S): PRJNA150307

REPOSITORIES: GEO

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Project description:Periodontitis affects 47.1% of adult population in the U.S. Porphyromonas gingivalis is an opportunistic oral pathogen that colonizes the oral mucosa, invades myeloid dendritic cells and accesses the bloodstream, brain, placenta and other organs in human with periodontitis. Periodontitis also sustains a chronic long-term pro-inflammatory immune disorder, potentially contributing to other systemic conditions such as cardiovascular disease, type 2 diabetes mellitus, adverse pregnancy outcomes, and osteoporosis. However, the role of P. gingivalis minor and major fimbriae in DC-SIGN-TLR2 crosstalk during traverses from oral mucosa to these distant sites and its influence on survival of P. gingivalis within DCs and its immune-mechanism involve at molecular/transcriptome level has not been examined. In this study to address the role of fimbriae we utilized defined bacterial mutants that solely express minor fimbriae (Mfa1+Pg), major fimbriae (FimA+Pg) or are deficient in both fimbriae (MFB) and compared with un-infected control. P. gingivalis strains were maintained anaerobically (10% H2, 10% CO2, and 80% N2) in a Forma Scientific anaerobic system glove box model 1025/1029 at 37Â°C in Difco anaerobe broth MIC. Mutant strains were maintained using erythromycin (5 Î¼g/ml) for mutant Mfa1+Pg, tetracycline (2 Î¼g/ml) for mutant FimA+Pg and both erythromycin and tetracycline for double fimbriae mutant MFB. Bacterial suspensions were washed five times in PBS and re-suspended for spectrophotometer reading at OD 660 nm of 0.11, which previously determined to be equal to 5 x 107 CFU. For bacterial CFSE staining, the suspension were washed (3 times) and re-suspended in 5 Î¼M of CFSE in PBS. The bacteria were incubated for 30 min at 37Â°C in the dark. MoDCs were pulsed with Pg381, Mfa1+Pg, FimA+Pg and MFB at 10 MOI and incubated with the MoDCs for 12 hours and each experimental condition was performed in triplicate. To facilitate our understanding on host immunity and defense mechanism of this pathogen, here we used the Illumina High-throughput RNA-seq transcriptome profiling to investigate the myeloid dendritic cells response to oral Amphibiont (1. Pg381, 2. Mfa1+Pg, 3. FimA+Pg, 4. MFB and 5. Un-infected control group).

Project description:E. coli K-12 BW25113 mutant strain hha expression in biofilm cells relative to E. coli wild-type strain expression in biofilm cells. Samples were cultured in LB with glasswool at 37C for 4 hours and in LB glu with glasswool at 37C for 4, 15 and 24 hours. Hha is a temperature- and osmolarity-dependent modulator of gene expression that is induced 30-fold in Escherichia coli biofilms. Here we show through whole-transcriptome analysis that Hha decreases biofilm formation in both LB and LB glu media by (i) repressing fliC encoding the main structural flagellar protein flagellin, (ii) by repressing fimA encoding the major structural subunit of type I fimbriae, (iii) by repressing ihfA encoding a subunit of the transcriptional regulator IHF that induces the transcription of type I fimbriae genes, (iv) by regulating tnaA encoding tryptophanase that inhibits biofilms, and (v) by repressing ybaJ that forms an operon with hha. Corroborating the microarray data, hha deletion increased motility 3.2 ± 0.1-fold, decreased extracellular indole concentrations 12 ± 2-fold, and decreased type I fimbriae (as measured by yeast agglutination). Biofilm tests using single and double mutants of fimA and ihfA and transcriptional studies of the fimA, ihfA and ybaJ-hha promoters confirmed that Hha represses biofilm by inhibiting type I fimbriae production and that it negatively regulates its own transcription and that of ybaJ. Nickel-enhanced DNA microarrays to determine in vivo Hha binding sites confirmed that Hha binds the ybaJ-hha promoter, that it binds fimZ, a positive regulator of fimA, and that it binds to the rare codon tRNAs argU, ileXY, and proL. Sequence analysis of fimZ, fimB, fimE, and the type I fimbriae gene cluster fimAICDFGH revealed a high bias for the rare codons of arginine, isoleucine, proline, leucine, and threonine, and overexpressing Hha leads to cell death. Therefore, it appears Hha decreases biofilms by decreasing type I fimbriae production as a result of inhibiting synthesis of tRNAs for rare codons. Keywords: effect of hha deletion in biofilm formation 4 hr LB and 4,15 and 24 hr LB glu

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Salmonella Typhimurium stbC mutant

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