title: Inverse regulation in the metabolic genes pckA and metE revealed by proteomic analysis of the Salmonella RcsCDB regulon.
abstract: The RcsC, RcsD, and RcsB proteins compose a system used by enteric bacteria to sense envelope stress. Signal transmission occurs from the sensor RcsC to the transcriptional regulator RcsB. Accessory proteins, such as IgaA, are known to adjust the response level. In a previous transcriptomic study, we uncovered 85 genes differentially expressed in Salmonella enterica serovar Typhimurium igaA mutants. Here, we extended these observations to proteomics by performing differential isotope-coded protein labeling (ICPL) followed by liquid chromatography-electrospray ionization tandem mass spectrometry. Five-hundred five proteins were identified and quantified, with 75 of them displaying significant changes in response to alterations in the RcsCDB system. Divergent expression at the RNA and protein level was observed for the metabolic genes pckA and metE, involved in gluconeogenesis and methionine synthesis, respectively. When analyzed in diverse environmental conditions, including the intracellular niche of eukaryotic cells, inverse regulation was more evident for metE and in bacteria growing in defined minimal medium or to stationary phase. The RcsCDB system was also shown to repress the synthesis of the small RNA FnrS, previously reported to modulate metE expression. Collectively, these findings provide new insights into post-transcriptional regulatory mechanisms involving the RcsCDB system and its control over metabolic functions.
authors.affiliation: Laboratorio de Proteómica, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain.
authors.forename: Alberto
authors.initials: A
authors.lastname: Paradela
authors.forename: Javier F
authors.initials: JF
authors.lastname: Mariscotti
authors.forename: Rosana
authors.initials: R
authors.lastname: Navajas
authors.forename: Antonio
authors.initials: A
authors.lastname: Ramos-Fernández
authors.forename: Juan Pablo
authors.initials: JP
authors.lastname: Albar
authors.forename: Francisco
authors.initials: F
authors.lastname: García-del Portillo
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D002851:Chromatography, High Pressure Liquid; D017931:DNA Primers; D005798:Genes, Bacterial; D008660:Metabolism / Q000235:genetics*; D020543:Proteome; D012323:RNA Processing, Post-Transcriptional; D060888:Real-Time Polymerase Chain Reaction; D018085:Regulon; D012486:Salmonella typhimurium / Q000235:genetics / Q000378:metabolism*; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry; D059467:Transcriptome
chemical_list: D001426:Bacterial Proteins; D017931:DNA Primers; D020543:Proteome