Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

Comparative Genomic Analysis of PhoP Regulon in S. Typhi and S. Typhimurium

ABSTRACT: Transcriptional profiling of three sequenced S. enterica strains: S. Typhimurium LT2, S. Typhi CT18, and S. Typhi Ty2 in PhoP-inducing and non-inducing conditions in vitro, and compared these results to profiles of phoP-/Q- mutants derived from S. Typhimurium LT2 and S. Typhi Ty2. Two-condition experiment: Each strain above was grown in PhoP-inducing (Low Magnesium concentration) and PhoP non-inducing conditions (High Magnesium concentration) with 1 dye reversal.

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

SUBMITTER: Regina LaRocque

PROVIDER: E-GEOD-17670 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

Comparative proteomic analysis of the PhoP regulon in Salmonella enterica serovar Typhi versus Typhimurium.

Charles Richelle C RC Harris Jason B JB Chase Michael R MR Lebrun Lauren M LM Sheikh Alaullah A LaRocque Regina C RC Logvinenko Tanya T Rollins Sean M SM Tarique Abdullah A Hohmann Elizabeth L EL Rosenberg Ian I Krastins Bryan B Sarracino David A DA Qadri Firdausi F Calderwood Stephen B SB Ryan Edward T ET

PloS one 20090910 9

<h4>Background</h4>S. Typhi, a human-restricted Salmonella enterica serovar, causes a systemic intracellular infection in humans (typhoid fever). In comparison, S. Typhimurium causes gastroenteritis in humans, but causes a systemic typhoidal illness in mice. The PhoP regulon is a well studied two component (PhoP/Q) coordinately regulated network of genes whose expression is required for intracellular survival of S. enterica.<h4>Methodology/principal findings</h4>Using high performance liquid chr ...[more]

PMID: 19746165

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Project description:Glucose-lysine based Maillard reaction products (MRPs) are introduced to the human body via food ingestion or are synthesized in vivo. Depending on reaction conditions, they represent a mixture of compounds with diverse chemical structures and physiological properties. MRPs may also be a potential nutrient source for Salmonella, a major foodborne gastrointestinal pathogen. This study was designed to determine the growth and transcriptional responses of S. Typhimurium LT2 to MRPs generated at low water activity to simulate the reaction occurring during food processing and storage. Maillard reactions between N-Î±-acetyl-lysine and glucose were varied in time (4, 23, and 143 h) to generate sub-samples with prevailing Amadori compound, advanced glycation end products (AGEs), or melanoidines respectively. The addition of MRP up to 5 mg mL-1 to defined media with 0.4% glucose had no effect on S. Typhimurium LT2 growth. In media, where the MRP sub-samples (4 and 23 h) served as the only carbon source, MRP assimilation by S. Typhimurium LT2 was observed as secondary logarithmic growth phases (0.063 h-1 and 0.072 h-1) after the growth on glucose available in the MRP reaction mixtures (0.479 h-1). The MRPs sub-sample with the highest concentration of melanoidines (143 h) also supported S. Typhimurium LT2 growth (0.368 h-1). Of the three MRPs sub-samples, the Amadori compound was the preferred carbon source for S. Typhimurium LT2 as evidenced by its almost complete disappearance (98%). Decreases in AGEs (37%) and melanoidines (15%), when incubated with S. Typhimurium LT2, also occurred. Transcription profiles of the cells grown on the MRPs fractions revealed predominant up-regulation of genes associated with the functional groups of energy metabolism, fatty and phospholipid metabolism, cellular process, and regulatory functions, and general down-regulation of the genes in the groups of amino acid biosynthesis, protein synthesis and transcription, transport and binding proteins, and DNA metabolism. The carbon flow in tricarboxylic acid (TCA) cycle partitioned by the glyoxylate cycle appeared to play an essential role in the assimilation of glucose-lysine-derived MRPs. The high expression level of numerous genes encoding hypothetical proteins or proteins with unknown function suggested the presence of genes whose role in glucose-lysine MRPs catabolism in Salmonella remains to be determined. This study was designed to determine the growth and transcriptional responses of S. Typhimurium LT2 to MRPs generated at low water activity to simulate the reaction occurring during food processing and storage. Maillard reactions between N-Î±-acetyl-lysine and glucose were varied in time (4, 23, and 143 h) to generate sub-samples with prevailing Amadori compound, advanced glycation end products (AGEs), or melanoidines respectively. Total bacterial RNA was isolated as previously described and the RNA samples were then converted to fluorescently-labeled cDNA and hybridized to S. Typhimurium microarrays version 5 (NIAID's Pathogen Functional Genomics Resource Center). Real-time PCR and physiological experiments were performed to validate the microarray data. In all supplementary files channel A = Cy3, channel B = Cy5.

Project description:In many Gram-negative bacteria, the stress sigma factor of RNA polymerase, σS/RpoS, remodels global gene expression to reshape the physiology of quiescent cells and ensure their survival under non-optimal growth conditions. In the foodborne pathogen Salmonella enterica serovar Typhimurium, σS is also required for biofilm formation and virulence. We have recently shown that a ΔrpoS mutation affects the magnesium content of Salmonella and expression of the primary Mg2+-transporter CorA. The other two Mg2+-transporters of Salmonella are encoded by the PhoP-activated mgtA and mgtB genes expressed under magnesium starvation, whereas the corA gene is expressed constitutively. The σS control of corA prompted us to evaluate the impact CorA in quiescent Salmonella cells, by using global and analytical proteomic analyses and physiological assays. The ΔcorA mutation conferred a competitive disadvantage to exit from stationary phase, and slightly impaired motility, but had no effect on total and free cellular magnesium contents. In contrast to the wild type strain, the ΔcorA mutant produced MgtA, but not MgtB, in the presence of high extracellular magnesium concentration. Under these conditions, MgtA production in the ΔcorA mutant did not require PhoP and, consistently, a ΔmgtA, but not a ΔphoP, mutation slightly reduced the magnesium content of the ΔcorA mutant. Nevertheless, the ΔphoP mutation strongly impaired growth and motility, in the absence of CorA only and independently of the extracellular magnesium concentration, unraveling the importance of PhoP-dependent functions in the absence of CorA. Under these conditions, several proteins involved in flagella formation, chemotaxis and secretion were affected by the ΔcorA and ΔphoP mutations in combination, but not alone. Altogether, our data pinpoint a regulatory network, where the absence of CorA is sensed and its physiological consequences alleviated by induction of MgtA- and PhoP- dependent compensatory mechanisms.

Dataset Information

Comparative Genomic Analysis of PhoP Regulon in S. Typhi and S. Typhimurium

Publications

Comparative proteomic analysis of the PhoP regulon in Salmonella enterica serovar Typhi versus Typhimurium.

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