title: Inhibition of fumarase by bismuth(III): implications for the tricarboxylic acid cycle as a potential target of bismuth drugs in Helicobacter pylori.
abstract: Helicobacter pylori causes various gastric diseases, such as gastritis, peptic ulcerations and gastric cancer. Triple therapy combining bismuth compounds with two antibiotics is the cornerstone of the treatment of H. pylori infections. Up to now, the molecular mechanisms by which bismuth inhibits the growth of H. pylori are far from clear. In the bacterial tricarboxylic acid (TCA) cycle, fumarase catalyses the reversible hydration of fumarate to malic acid. Our previous proteomic work indicated that fumarase was capable of bismuth-binding. The interactions as well as the inhibitory effects of bismuth to fumarase have been characterized in this study. The titration of bismuth showed that each fumarase monomer binds one mol equiv of Bi(3+), with negligible secondary structural change. Bismuth-binding results in a near stoichiometric inactivation of the enzyme, leading to an apparent non-competitive mechanism as reflected by the Lineweaver-Burk plots. Our collective data indicate that the TCA cycle is a potential molecular target of bismuth drugs in H. pylori.
authors.affiliation: The Laboratory of Integrative Biosciences, College of Life Sciences, Sun Yat-Sen University, Guangzhou, 510275, China.
authors.forename: Zhuo
authors.initials: Z
authors.lastname: Chen
authors.forename: Qinglu
authors.initials: Q
authors.lastname: Zhou
authors.forename: Ruiguang
authors.initials: R
authors.lastname: Ge
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001729:Bismuth / Q000494:pharmacology* / Q000627:therapeutic use; D002952:Citric Acid Cycle / Q000187:drug effects*; D005649:Fumarate Hydratase / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000235:genetics; D016481:Helicobacter Infections / Q000188:drug therapy; D016480:Helicobacter pylori / Q000187:drug effects* / Q000201:enzymology*; D006801:Humans; D008958:Models, Molecular; D017434:Protein Structure, Tertiary
chemical_list: D001426:Bacterial Proteins; D005649:Fumarate Hydratase; D001729:Bismuth