Date of Award

2002

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biology

Abstract

Helicobacter pylori is known to be associated with gastritis, peptic ulcer disease and gastric cancer. Evidence strongly suggests that more than 50% of the population of the world is colonized by H. pylori with and without disease symptoms. It is now considered one of the most common human pathogens. Phosphate is an essential nutrient for all cells and its availability in the environment varies widely. In H. pylori , phosphate uptake is dependent upon the pH of medium and the rate of uptake is greatly reduced in acidic environments. HP1491 from ATCC 26695 encodes a putative phosphate permease, which has 56% similarity to phosphate permeases/ion co-transporters from Saccharomyces cerevisiae , that also are regulated by phosphate limitation and pH. Mutant strain, HPmt1491, was obtained by insertional inactivation with suicide plasmid pBCα5 that carried PCR product of HP1491 gene. Comparison of phosphate uptake activity in wild type and mutant strains in neutral and acidic (pH 4.5) media showed that the phosphate permease encoded by HP1491 is responsible for maintaining the low activity observed during low pH and may have a role in the initial rate of activity and recovery of various rates after the initial burst of activity. Further studies are necessary to completely define the HP1491 gene products role in regulation of phosphate uptake.

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