Supramolecular assembly and acid resistance of Helicobacter pylori urease

Helicobacter pylori, an etiologic agent in a variety of gastroduodenal diseases, produces a large amount of urease, which is believed to neutralize gastric acid by producing ammonia for the survival of the bacteria. Up to 30% of the enzyme associates with the surface of intact cells upon lysis of neighboring bacteria. The role of the enzyme at the extracellular location has been a subject of controversy because the purified enzyme is irreversibly inactivated below pH 5. We have determined the crystal structure of H. pylori urease, which has a 1.1 MDa spherical assembly of 12 catalytic units with an outer diameter of ∼160 Å. Under physiologically relevant conditions, the activity of the enzyme remains unaffected down to pH 3. Activity assays under different conditions indicated that the cluster of the 12 active sites on the supramolecular assembly may be critical for the survival of the enzyme at low pH. The structure provides a novel example of a molecular assembly adapted for acid resistance that, together with the low Km value of the enzyme, is likely to enable the organism to inhabit the hostile niche.

[1]  B E Dunn,et al.  Purification and characterization of urease from Helicobacter pylori. , 1990, The Journal of biological chemistry.

[2]  B E Dunn,et al.  Surface localization of Helicobacter pylori urease and a heat shock protein homolog requires bacterial autolysis , 1996, Infection and immunity.

[3]  P. Karplus,et al.  The crystal structure of urease from Klebsiella aerogenes. , 1995, Science.

[4]  A. Horwich,et al.  The crystal structure of the asymmetric GroEL–GroES–(ADP)7 chaperonin complex , 1997, Nature.

[5]  R. Hausinger,et al.  Purification and characterization of the nickel-containing multicomponent urease from Klebsiella aerogenes. , 1987, The Journal of biological chemistry.

[6]  K. Wilson,et al.  A new proposal for urease mechanism based on the crystal structures of the native and inhibited enzyme from Bacillus pasteurii: why urea hydrolysis costs two nickels. , 1999, Structure.

[7]  R J Read,et al.  Crystallography & NMR system: A new software suite for macromolecular structure determination. , 1998, Acta crystallographica. Section D, Biological crystallography.

[8]  M. Stewart,et al.  Structural comparison of urease and a GroEL analog from Helicobacter pylori , 1992, Journal of bacteriology.

[9]  H. Mobley,et al.  Purification and N-terminal analysis of urease from Helicobacter pylori , 1990, Infection and immunity.

[10]  R. Hausinger,et al.  Site‐directed mutagenesis of Klebsiella aerogenes urease: Identification of histidine residues that appear to function in nickel ligation, substrate binding, and catalysis , 1993, Protein science : a publication of the Protein Society.

[11]  P. Karplus,et al.  Kinetic and structural characterization of urease active site variants. , 2000, Biochemistry.

[12]  G J Kleywegt,et al.  Detection, delineation, measurement and display of cavities in macromolecular structures. , 1994, Acta crystallographica. Section D, Biological crystallography.

[13]  B. Mee,et al.  Purification and characterization of the urease enzymes of Helicobacter species from humans and animals , 1992, Infection and immunity.

[14]  G. Sachs,et al.  A H+-gated urea channel: the link between Helicobacter pylori urease and gastric colonization. , 2000, Science.

[15]  B. Dunn,et al.  Localization of Helicobacter pylori urease and heat shock protein in human gastric biopsies , 1997, Infection and immunity.

[16]  J. Navaza,et al.  AMoRe: an automated package for molecular replacement , 1994 .

[17]  B. Dunn,et al.  Synthesis and activity of Helicobacter pylori urease and catalase at low pH. , 1997, Gut.

[18]  R. Hausinger,et al.  Identification of the essential cysteine residue in Klebsiella aerogenes urease. , 1991, The Journal of biological chemistry.

[19]  D. Morgan,et al.  Essential role of urease in pathogenesis of gastritis induced by Helicobacter pylori in gnotobiotic piglets , 1991, Infection and immunity.

[20]  D. Graham,et al.  Epidemiology of Helicobacter pylori in an asymptomatic population in the United States. Effect of age, race, and socioeconomic status. , 1991, Gastroenterology.

[21]  B. Dunn,et al.  Helicobacter pylori Containing Only Cytoplasmic Urease Is Susceptible to Acid , 1998, Infection and Immunity.

[22]  D. Graham,et al.  Characterization of the Helicobacter pylori urease and purification of its subunits. , 1991, Microbial pathogenesis.

[23]  H. Mobley,et al.  Expression of catalytically active recombinant Helicobacter pylori urease at wild-type levels in Escherichia coli , 1993, Infection and immunity.

[24]  G. Sachs,et al.  The role of internal urease in acid resistance of Helicobacter pylori. , 1998, Gastroenterology.

[25]  J. Zou,et al.  Improved methods for building protein models in electron density maps and the location of errors in these models. , 1991, Acta crystallographica. Section A, Foundations of crystallography.

[26]  K. Wilson,et al.  The complex of Bacillus pasteurii urease with acetohydroxamate anion from X-ray data at 1.55 Å resolution , 2000, JBIC Journal of Biological Inorganic Chemistry.

[27]  R. Rappuoli,et al.  Helicobacter pylori virulence and genetic geography. , 1999, Science.

[28]  Z. Otwinowski,et al.  [20] Processing of X-ray diffraction data collected in oscillation mode. , 1997, Methods in enzymology.