title: Nickel-binding and accessory proteins facilitating Ni-enzyme maturation in Helicobacter pylori.
abstract: Helicobacter pylori colonizes the human gastric mucosa and this can lead to chronic gastritis, peptic and duodenal ulcers, and even gastric cancers. The bacterium colonizes over one-half of the worlds population. Nickel plays a major role in the bacteriums colonization and persistence attributes as two nickel enzyme sinks obligately contain the metal. Urease accounts for up to 10% of the total cellular protein made and is required for initial colonization processes, and the hydrogen oxidizing hydrogenase provides the bacterium a high-energy substrate yielding low potential electrons for energy generation. A battery of accessory proteins are needed for maturation or activation of each of the apoenzymes. These include Ni-chaperones and GTPases, some of which are unique to each Ni-enzyme and others that are individually required for maturation of both the Ni-enzymes. H. pylori's need for some conventional hydrogenase maturation proteins playing roles in urease maturation may have to do with the poor nickel-sequestering ability of the UreE urease maturation protein compared to other systems. H. pylori also possesses a NixA nickel specific permease, a nickel dependent regulator (NikR), a recently identified nickel efflux system (CznABC), and a histidine-rich heat shock protein, HspA. Based on mutant analysis approaches all these proteins have roles in nickel homeostasis, in urease expression, and in host colonization. The His-rich putative nickel storage proteins Hpn and Hpn-like play roles in nickel detoxification and may influence the levels of Ni-activated urease that can be achieved.
authors.affiliation: Department of Microbiology, University of Georgia, Athens, GA 30602, USA. rmaier@uga.edu
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Maier
authors.forename: Stéphane L
authors.initials: SL
authors.lastname: Benoit
authors.forename: Susmitha
authors.initials: S
authors.lastname: Seshadri
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D016480:Helicobacter pylori / Q000201:enzymology* / Q000235:genetics; D006801:Humans; D006864:Hydrogenase / Q000235:genetics / Q000378:metabolism; D009532:Nickel / Q000378:metabolism*; D014510:Urease
chemical_list: D001426:Bacterial Proteins; D027682:Cation Transport Proteins; C512594:CznA protein, Helicobacter pylori; D006360:Heat-Shock Proteins; C113725:HspA protein, bacteria; C095257:NixA protein, Helicobacter pylori; D009532:Nickel; D006864:Hydrogenase; D014510:Urease