Functional disruption of HypB, a GTPase of Helicobacter pylori, by bismuth.

Bismuth (Bi(3+)) binds equal molar amounts of HypB from Helicobacter pylori at the conserved metal site with a dissociation constant of 0.94 (±0.25) × 10(-17) μM, and concomitantly induces the protein dimerization similarly to Ni(2+). Excess Bi(3+) causes HypB further oligomerization, leading to HypB GTPase dysfunction. The results extend our understanding on the inhibitory mechanism of bismuth drugs against the pathogen.