Introduction to ST laboratory

Current research in my laboratory is focused on “Molecular biology and identification of Burkholderia pseudomallei virulent factors via RpoS regulon, RpoN regulon, quorum sensing and polyphosphate kinase network by proteomic profiles and computational analysis”.

Burkholderia pseudomallei is a bacterial pathogen causing the melioidosis disease, which is predominantly found in tropical areas of Southeast Asia and Northern Australia. The RpoS subunit of RNA polymerase is an alternative sigma factor that is strongly induced during entry into stationary phase and considered to be a master stress response regulator important for response to a variety of stress conditions. The genes of RpoS regulation in many pathogenic bacteria are involved in virulent properties such as Catalase enzymes, DpsA, and some netwok interaction such as quorum sensing and polyphosphate kinase. There also has a RpoN regulon that is function differently with RpoS family. Identification of RpoS and RpoN regulons and theirs network with quorum sensing and polyphosphate kinase of B. pseudomallei, rpoS, rpoN, bpsI and ppk mutants were constructed and theirs properties were determined.

In rpoS, we have reported the role of the gene involved in starvation and oxidative stress
In rpoS, we have drawn the OxyR and RpoS network in regulating of catalase I with DpsA [more2].
In ppk, we have concluded that a ppk plays an importance role in biofilm formation of the bacteria [more3].
The proteomic profile of rpoS regulon was studied and compared to a reference map of the wild-type. We also identify some virulent factors by comparing with a non-virulent species, B. thailandensis [more4].
In attempt to identify the RpoS regulon, the use of 2-DE analysis of B. pseudomallei RpoS mutant compared with the wild-type could identify more than 70 different spots. The RpoS-dependent genes are determined in 14 functional main-role categories which the most proteins are identified to stress response function. Down-regulated proteins in rpoS mutant contained 63 protein spots which are positively controlled by RpoS. We extended the RpoS-controlled genes of co-expression based on RpoS-dependent promoter prediction, gene organization and operon prediction. We are able to prove co-expression of RpoS regulation using RT-PCR. Based on this information, we suggest that the RpoS regulation in B. pseudomallei has some different pattern of RpoS regulon from other gram-negative bacteria [more5].

Furthermore, the comparative analysis of proteomics on constructed B. pseudomallei mutants that are related to virulent characters such as rpoN, quorum sensing and polyphosphate kinase are performed. Our study could provide the useful information of global intracellular protein expression and is a valuable starting point for analyzing a proteomic pathogenicity of the bacterial pathogen.


Last modified: 12-Nov-2009
© 2008-2009 Department of Biochemistry, Faculty of Science, Mahidol University