Quorum Sensing in Burkholderia pseudomallei
(Collaborative project with Universiti Kebangsaan Malaysia)
Many bacteria have evolved the ability to condition culture medium by secreting low-molecular weight signaling pheromones in association with their growth phase to control the expression of specific genes, a process termed quorum sensing. Quorum sensing bacteria produce and release chemical molecules called autoinducers that increase in concentration as a function of cell density. The accumulation of a stimulatory concentration of an extracellular autoinducer can only occur when sufficient number of cells, or a "quorum", is present. Quorum sensing modulates a variety of physiological responses including bioluminescence, swarming, swimming and twitching motility, antibiotic biosynthesis, biofilm differentiation, and the production of virulence determinants in pathogens.
Burkholderia pseudomallei is a Gram-negative environmental saprophyte endemic to many parts of South-east Asia and northern Australia. Exposure to this organism, usually via transpercutaneous, respiratory, or oral means, causes an illness known as melioidosis. Although the clinical symptoms of melioidosis can be extremely varied, the most common presenting symptom is severe pulumorary distress, which, if left untreated, can eventually progress to septicaemia and death. Since morbidity and mortality as a result of B. pseudomallei infection currently remains at an unacceptably high level, there is a need to develop novel strategies to aid in both the early detection and effective treatment of B. pseudomallei infection.
At present, very little is known about the molecular mechanisms that underlie B. pseudomallei virulence. Genetically, the B. pseudomallei genome is 7 Mb consisting of two chromosomes of 4 Mb and 3 Mb. Homologs of LuxI, the autoinducer synthase, could be identified in the genome sequence of B. pseudomallei. This project aims to determine if local isolates of B. pseudomallei harbor luxI gene homologs that enable production of N-acyl-homoserine lactone (AHLs) for cell-cell communication. We also aim to have a genome-wide expression profile of B. pseudomallei genes that are controlled by quorum sensing using DNA microarrays.
Principal Investigators at MUST
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