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Altered proteome in Burkholderia pseudomallei rpoE operon knockout mutant: Insights into mechanisms of rpoE operon in stress tolerance, survival, and virulence

Medical Molecular Biology Unit, Office for Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
Journal of Proteome Research (Impact Factor: 5). 05/2007; 6(4):1334-41. DOI: 10.1021/pr060457t
Source: PubMed

ABSTRACT We have previously shown that the alternative sigma factor sigmaE (RpoE), encoded by rpoE, is involved in stress tolerance and survival of Burkholderia pseudomallei. However, its molecular and pathogenic mechanisms remain unclear. In the present study, we applied gel-based, differential proteomics to compare the cellular proteome of an rpoE operon knockout mutant (RpoE Mut) to that of wild-type (K96243 WT) B. pseudomallei. Quantitative intensity analysis (n = 5 gels from 5 individual culture flasks in each group) revealed significantly differential expression of 52 proteins, which were subsequently identified by Q-TOF MS/MS. These included oxidative, osmotic, and other stress response proteins; chaperones; transcriptional/translational regulators; metabolic enzymes; proteins involved in cell wall synthesis, fatty synthesis, glycogen synthesis, and storage; exported proteins; secreted proteins; adhesion molecule; protease/peptidase; protease inhibitor; signaling proteins; and other miscellaneous proteins. The down-regulation of several stress response proteins, chaperones, transcriptional/translational regulators, and proteins involved in cell wall synthesis in RpoE Mut provided some new insights into the mechanisms of the rpoE operon for the stress tolerance and survival of B. pseudomallei. In addition, the proteomic data and in vivo study indicated that the rpoE operon is also involved in the virulence of B. pseudomallei. Our findings underscore the usefulness of proteomics for unraveling pathogenic mechanisms of diseases at the molecular level.

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    • "Proteomics studies demonstrated that the rpoE mutant displayed reduced expression of a number of stress response proteins and chaperones, as well as transcriptional regulators and proteins involved in cell wall synthesis (Thongboonkerd et al., 2007). The inability of the rpoE mutant to repair cell wall damage is probably responsible for the decreased intracellular survival of this mutant in macrophages and the observed attenuation in BALB/c mice (Korbsrisate et al., 2005; Thongboonkerd et al., 2007). However, the direct regulation of unknown virulence factors by RpoE cannot be completely excluded. "
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    • "This induction was not seen in the AL30 mutant. Recently, on the basis of proteomic analysis, we have reported that the expressions of GroEL and HtpG are downregulated in the rpoE operon mutant (Thongboonkerd et al., 2007). These data supported our hypothesis that the B. pseudomallei AL30 mutant has a defect in the regulation of heat shock protein, resulting in a heat-sensitive phenotype. "
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