FIG. 2.

Western blot analysis and urease activity of purified membrane fractions from wild-type and HP0244 deletion strains of H. pylori. Representative Western blots are shown for UreA, UreB, UreE, and UreI from wild-type (A) and HP0244 deletion (B) strains that were exposed to pH 7.4 and pH 4.5. The intensities of the protein bands were measured and converted to expression ratios of pH 4.5 to pH 7.4. (C) The amounts of UreA, UreB, and UreE but not UreI protein increased after incubation at pH 4.5 for 30 min in wild-type H. pylori, whereas the absence of HP0244 abolished the recruitment of UreA and UreB, but not UreE, to the membrane. (D) Urease activities from both membrane and soluble fractions incubated at pH 4.5 and pH 7.4 from wild-type and HP0244 deletion strains were measured. The urease activity of the membrane fraction increased ∼2-fold after incubation at pH 4.5 for 30 min in the wild-type strain (black bars) but not in the HP0244 deletion strain (gray bars). Urease activity is expressed as a percentage of that in the pH 7.4 control.