INVERSE REGULATION IN THE METABOLIC GENES PCKA AND METE REVEALED BYPROTEOMIC ANALYSIS OF THE SALMONELLA RCSCDB REGULON

ALBERTO PARADELA; JAVIER FERNANDO MARISCOTTI; ROSANA NAVAJAS; ANTONIO RAMOS-FERNANDEZ; JUAN PABLO ALBAR; FRANCISCO GARCÍA-DEL PORTILLO

Geneva

Congreso; HUPO 2011 10th Annual World Congress; 2011

The Human Proteome Organisation (HUPO)

Background: RcsC, RcsD and RcsB are proteins used by enteric bacteria to sense envelope and osmotic stress. The signal is transmitted from the sensor RcsC to the transcriptional regulator RcsB. Accessory proteins, such as IgaA, adjust the response. In a previous transcriptomic study, we uncovered 85 genes differentially expressed in Salmonella enterica serovar Typhimurium igaA mutants. Methods: Previous observations obtained through transcriptomics analysis are extended here using differential proteomics by performing differential isotope-coded protein labeling (ICPL) followed by liquid chromatography/e1ectrospray ionization tandem mass spectrometry. Results: 505 proteins were identified and quantified, with 75 of them displaying statistically significant changes in response to alterations in the RcsCDB system Divergent expression at the RNA and protein level was observed fur the metabolic genes pckA and metE, involved in gluconeogenesis and methionine synthesis, respectively. This behavior was analyzed in diverse growth conditions, including the intracellular niche of eukaryotic cells. Inverse regulation was more evident for metE and in bacteria growing in a defined minimal medium or to stationary phase. The RcsCDB system was also shown to repress the synthesis of the small RNA FnrS, previously known to modulate metE expression. Conclusion: Collectively, these findings provide new insights into posttranscriptional regulatory mechanisms involving the RcsCDB system and its control over metabolic functions.