ABSTRACT

Title of Dissertation / Thesis: EVALUATION OF THE ROLE OF BarA-UvrY TWO-COMPONENT SYSTEM IN ESCHERICHIA COLI.

Isha Patel, Masters, 2004

Dissertation / Thesis Directed By: Assistant Professor, Dr. Suman Mukhopadhyay, Department of Veterinary and Medicine

Pathogenic strains of Escherichia coli, a gram-negative bacterium, colonize the gastric mucosa and urinary tracts of birds, animals and human beings causing diseases like chronic gastritis, diarrhea, peptic ulceration, and urinary tract infections. Pathogenic strains cause a worldwide problem affecting 20% popuation in the U.S. The BarA-UvrY is a two-component system involved in bacterial adaptation and survival. The barA (bacterial adaptive response) gene, induced in uropathogenic E. coli upon contact with eukaryotic cell surface, plays a key role in attachment and colonizing urinary tract epithelia during infection and codes for the transmembrane sensor kinase, BarA. The UvrY protein, is a barA-regulated transcriptional modulator whose targets are yet to be determined.

Determination of genes under regulation of BarA-UvrY signaling cascade under various stress conditions will help in better understanding the overall role of this pathway in metabolic adaptation and pathogenesis. Microarray work done in the laboratory shows that BarA-UvrY regulates several stress-response and membrane-transport genes. One such gene identified from the microarray results, luxS, is involved in the detoxification of the S-adenosyl methionine in E. coli and produces a furanone, essential for cell density-dependent bacterial quorum sensing. LuxS is known to regulate virulence in E. coli. We chose to study the regulation of the luxS gene expression as it has not been studied in great detail. Using physiological approaches, we validated part of the microarray results.