Iron-containing urease in a pathogenic bacterium

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 108; no. 32; pp. 13095 - 13099
• Main Authors: Carter, Eric L, Tronrud, Dale E, Taber, Scott R, Karplus, P. Andrew, Hausinger, Robert P
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 09.08.2011; National Acad Sciences
• Subjects: Absorption - drug effects; Active sites; Anaerobic conditions; Bacteria; Biological Sciences; Bleaching; Cadmium; carnivores; Chromium; Crystal structure; Crystallography, X-Ray; Culture Media - pharmacology; dithionite; Electrons; Enzymes; ferrets; Helicobacter; Helicobacter mustelae; Helicobacter mustelae - drug effects; Helicobacter mustelae - enzymology; Helicobacter pylori; Ions; Iron; Iron - metabolism; Kinetics; Lysine; Mammals; Metal ions; Models, Molecular; Mustela; Nickel; Nickel - metabolism; Oxygen - metabolism; Pathogens; Spectrum Analysis; Urease; Urease - chemistry; Urease - isolation & purification; Urease - metabolism; Zinc
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1106915108

Helicobacter mustelae, a gastric pathogen of ferrets, synthesizes a distinct iron-dependent urease in addition to its archetypical nickel-containing enzyme. The iron-urease is oxygen-labile, with the inactive protein exhibiting a methemerythrin-like electronic spectrum. Significantly, incubation of the oxidized protein with dithionite under anaerobic conditions leads to restoration of activity and bleaching of the spectrum. Structural analysis of the oxidized species reveals a dinuclear iron metallocenter bridged by a lysine carbamate, closely resembling the traditional nickel-urease active site. Although the iron-urease is less active than the nickel-enzyme, its activity allows H. mustelae to survive the carnivore's low-nickel gastric environment.