A) Urease activity of strain KE88-3887 wild-type and <i>ccrp</i> mutants.

<p>Activity is expressed as percentage relative to wild-type in unsupplemented medium (set at 100%; no error bar). Results shown are the averages of six independent experiments; error bars denote standard deviations. Exact percentage values are indicated above the bars. Asterisks indicate a significant difference in urease activity between <i>ccrp</i> mutants and wild-type <i>H</i>. <i>pylori</i> (the P value was <0.001, as determined by Student's t test). B) Western blot using urease specific antiserum and strains as indicated above the lanes. Equal amounts of protein were loaded onto each lane. C) Urease activity of the wild-type strain and the <i>ccrp59</i> mutant in unsupplemented and nickel-supplemented media (as indicated in μM) shown as a percentage relative to wild-type in unsupplemented medium (set at 100%; no error bar). Results shown are the averages of six independent growth experiments; error bars denote standard deviations. Exact percentage values are indicated above the bars. Asterisks indicate a significant difference in urease activity between ccrp mutants and wild-type <i>H</i>. <i>pylori</i> (the P value was <0.001, as determined by Student's t test).