Effects of FlgZ variants on motility and RpoN stability. (A) Wild-type H. pylori strain ATCC 43504, flgZ:aphA3 and hp0959:aphA3 mutants were analyzed by western blotting for the proteins indicated in the top three panels. Construction of the mutant strains was described previously . Approximately 1 × 108 cells were lysed and loaded in each lane. Following protein transfer, nitrocellulose membranes were probed with antiserum directed against RpoN, FlaB or FlgZ proteins that were fused to the maltose-binding protein (MBP) as described . Results of motility assays are shown in the bottom panel. Each strain was inoculated into semisolid motility agar plates using a sterile toothpick and incubated 5 days at 37®C under microaerophilic conditions as described previously . (B) Wild-type or mutant alleles of flgZ were introduced into the hp0405 locus of the H. pylori flgZ:aphA3 mutant as described previously . The resulting strains were analyzed by western blotting for RpoN, FlaB and FlgZ (top three panels) and for motility (bottom panel) as described for panel A.