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Identified virulence factors of Helicobacter: Enzyme


Urease  

Related genes: ureA; ureB; ureE; ureF; ureG; ureH; ureI;
Keywords: Enzyme; Acid resistance; Colonization;
Structure features:
~550kDa nickel metalloenzyme comprised of two distinct subunits-UreA and UreB, the UreEFGH proteins are required for activation of urease by incorporating nickel ions into the urease apoenzyme, UreI functions as an acid-dependent urea channel.
PDB code: 1E9Z.
Functions:
An important colonization factor, contributes to acid resistance, epithelial cell damage, chemotactic behavior, and nitrogen metabolism.
Mechanism:
A Ni2+-containing enzyme, catalyzes the hydrolysis of urea to ammonium and carbon dioxide. Urea channels (UreI) present in the inner membrane are opened at pH<6.5, allowing delivery of urea to urease. The ammonia produced diffuses into, and thus buffers the periplasm.
References:
Mobley HL, et al., 1995. Molecular biology of microbial ureases. Microbiol. Rev. 59(3):451-480.
Weeks DL, et al., 2000. A H+-gated urea channel: the link between Helicobacter pylori urease and gastric colonization. Science 287(5452):482-485.
Montecucco C, Rappuoli R, 2001. Living dangerously: how Helicobacter pylori survives in the human stomach. Nat. Rev. Mol. Cell Biol. 2(6):457-466.
Bury-Mone S, et al., 2001. The Helicobacter pylori UreI protein: role in adaptation to acidity and identification of residues essential for its activity and for acid activation. Mol. Microbiol. 42(4):1021-1034.
Eaton KA, et al., 2002. In vivo complementation of ureB restores the ability of Helicobacter pylori to colonize. Infect. Immun. 70(2):771-778.








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