Project description:Salmonella is an important enteric pathogen that causes a spectrum of diseases varying from mild gastroenteritis to life threatening typhoid fever. Salmonella does not have lac operon. However, E. Coli, Salmonella’s close relative, has lac operon. Being an enteric pathogen like E. coli, Salmonella will also benefit from lac operon. Then, why Salmonella has lost lac operon?. To address this question, lacI, an important component of lac operon was expressed in Salmonella via pTrc99A plasmid. As a control, pTrc99A without lacI was also expressed in Salmonella. The effect of LacI on the transcription profile of Salmonella was analyzed using microarray technique.
Project description:We performed whole-genome transcriptomic analyses of the Salmonella Typhimimurium genome during glucose-phosphate stress. In particular, we wanted to elucidate the role of the the small RNA SgrS and protein regulator SgrT in the stress response.
Project description:The Salmonella enterica serovar Typhimurium (ST) mutant lacking the msbB gene (ΔmsbB) has been widely studied as a candidate for attenuated bacterial vectors in therapeutic applications. Deletion of msbB results in LPS with under-acylated lipid A, which lowers endotoxicity while maintaining structural integrity. This attenuation has traditionally been attributed to reduced TLR4 activation due to weaker interaction between the modified lipid A and TLR4. In our study, we confirmed that ΔmsbB ST was less lethal than wild-type (WT) ST in a mouse sepsis model. However, this difference persisted even in TLR4- and caspase-11-deficient mice, suggesting that LPS signaling is not the primary determinant of virulence. In vitro, bone marrow–derived macrophages (BMDMs) from TLR4- or caspase-11-deficient mice showed only modest reductions in ST-induced cell death and cytokine production. Importantly, ΔmsbB ST behaved similarly to WT ST in these assays, further indicating that LPS-mediated signaling is not central to the observed attenuation. Additionally, the mutant exhibited increased outer membrane permeability, likely contributing to its heightened antibiotic sensitivity—and reduced motility due to lower flagellin protein levels.
Project description:Salmonella is an important enteric pathogen that causes a spectrum of diseases varying from mild gastroenteritis to life threatening typhoid fever. Salmonella does not have lac operon. However, E. Coli, Salmonellaâs close relative, has lac operon. Being an enteric pathogen like E. coli, Salmonella will also benefit from lac operon. Then, why Salmonella has lost lac operon?. To address this question, lacI, an important component of lac operon was expressed in Salmonella via pTrc99A plasmid. As a control, pTrc99A without lacI was also expressed in Salmonella. The effect of LacI on the transcription profile of Salmonella was analyzed using microarray technique. Overall design The total RNA was isolated from Salmonella using âRNeasy Mini Kitâ (QIAGEN). Organism used: Salmonella enterica serovar Typhimurium LT2 * Slides: Agilentâs arrays (8x15k) AMADID: NO: 17809 * Starting material: Salmonella RNA in nuclease-free water * RNA Samples used: Wild type (WT), WT + pTrc99A+LacI (PTRC), WT + pTrc99A-LacI(Delta lac) * Labeling kit: MessageAmp⢠II-Bacteria RNA Amplification Kit from Ambion Cat # AM1790 * Labeling Method: T7 promoter based-linear amplification to generate labeled complementary RNA * Total RNA and cRNA Purification Kit: Qiagenâs RNeasy minikit Cat#74104 * Hybridization Kit: Agilentâs In situ Hybridzation kit 5184-3568 * RNA quality was checked using Bioanalyzer. The array slides were scanned immediately by PerkinElmer Scan array Gx Microarray scanner. The Scan array software (PerkinElmer) was used for grid wise normalization of array images. Two arrays were used with mutant and rescue experiments and dye swap experiments were included in the final analysis. The data was analysed by GeneSpring GX and Biointerpreter software from Genotypic Technology, Bangalore. The differential expression was considered if the Log 2 mean of at least -1 for the down regulated genes and +1 for the upregulated genes. We considered only the genes that were reproducible from both replicates.
Project description:FabR ChIP-chip on Salmonella enterica subsp. enterica serovar Typhimurium SL1344 using anti-Myc antibody against strain with chromosomally 9Myc-tagged FabR (IP samples) and wildtype strain (mock IP samples)
Project description:We performed whole-genome transcriptomic analyses of the Salmonella Typhimimurium genome during glucose-phosphate stress. In particular, we wanted to elucidate the role of the the small RNA SgrS and protein regulator SgrT in the stress response. Wild-type Salmonella cells, mutants of Salmonella either lacking sgrS or lacking SgrS RNA/ SgrT peptide function were subject to glucose-phoshate stress