Abstract:
B. pseudomallei, a pathogenic bacterium, causes melioidosis. This organism can survive in eukaryotic host cells by escaping oxidative stress, via the regulation of RpoS sigma factor. In this study, we have further characterized the RpoS-dependent oxidative stress response system using comparative proteomics analysis. Alterations in the proteomic profiles of B. pseudomallei wild-type and rpoS mutant strains exposed to hydrogen peroxide were analyzed. Using stringent criteria, the high confidence 176 hydrogen peroxide responsive proteins were identified, which were divided as 13 proteins from 2D-gels MALDI-TOF MS/MS and 163 proteins from 1D-gels LC MS/MS. A total of 26 proteins were discovered to be determined by the RpoS sigma factor. ScoA, which functions together with ScoB as a subunit of SCOT enzyme in lipid metabolism, was found to be regulated by RpoS and significantly down-regulated after hydrogen peroxide treatment. ScoA and ScoB have been predicted to organize as an operon using computational methods, and we have confirmed that they are indeed co-transcribed as single mRNA using RT-PCR and time-series gene expression data. Our study is the first to identify a role of RpoS in the down-regulation of SCOT expression in response to oxidative stress in B. pseudomallei."