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Chapter 16 : Urease

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Abstract:

Urease is produced by numerous taxonomically diverse bacterial species, including normal flora and nonpathogens. This enzyme is used for taxonomic identification and for diagnosis and follow-up after treatment, and is a vaccine candidate. synthesizes an extraordinary amount of urease. The purified enzyme, however, is not significantly more active than purified ureases from other species, but it simply represents a larger proportion of total cell protein in this species. Purified native urease has been examined by transmission electron microscopy and appears as a round, doughnut-shaped, hexagonal particle with a darkly staining core. The crystal structure of the related urease from has been solved by X-ray diffraction. For synthesis of a catalytically active urease, the accessory genes , , , , and also must be expressed. Mutants that lacked detectable urease activity were readily selected and had no apparent alteration of growth rates, demonstrating that enzyme activity was not necessary for viability in vitro. Polymerase chain reaction (PCR) amplification of urease genes has been used in methods to establish the presence of viable or nonviable . Studies in monkeys with purified urease apoenzyme or in humans using salmonella / deletion mutant expressing the apoenzyme demonstrated little or no protection against infection. Other studies in monkeys, however, showed significant reduction in colonization.

Citation: Mobley H. 2001. Urease, p 179-191. In Mobley H, Mendz G, Hazell S (ed), . ASM Press, Washington, DC. doi: 10.1128/9781555818005.ch16

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Figures

Image of Figure 1
Figure 1

Purified urease electrophoresed on an SDS-polyacrylamide gel. Protein (10 µg) from each purification step was electrophoresed on a 10 to 20% polyacrylamide gradient gel and stained with Coomassie Blue ( ). Lanes (from left to right): crude lysate of DEAE-Sepharose, phenyl-Sepharose, Mono-Q, Superose 6, high molecular weight protein standards, low molecular weight protein standards. Molecular masses of the two subunits, predicted from the nucleotide sequence, are shown in the right margin.

Citation: Mobley H. 2001. Urease, p 179-191. In Mobley H, Mendz G, Hazell S (ed), . ASM Press, Washington, DC. doi: 10.1128/9781555818005.ch16
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Image of Figure 2
Figure 2

Space-filling model of the predicted urease crystal structure. The primary amino acid sequence of urease was overlaid onto the solved crystal structure of urease ( ). The front (A) and back (B) views of the two subunits, UreA (dark) and UreB (light) are shown. Note the two nickel atoms inserted into the enzyme active site (panel B). The holoenzyme is composed of six copies of the heterodimer displayed in the figure; the crystal structure of the urease has not been determined directly (figure designed by Ron Guiles and Nereus Gunther, University of Maryland).

Citation: Mobley H. 2001. Urease, p 179-191. In Mobley H, Mendz G, Hazell S (ed), . ASM Press, Washington, DC. doi: 10.1128/9781555818005.ch16
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Image of Figure 3
Figure 3

Model for synthesis of a catalytically active urease in The urease gene cluster, composed of seven chromosomally encoded genes, is present as a single copy on the chromosome. The genes and encode the 26.5-kDa and 60.3-kDa subunits, respectively. Six copies of each subunit spontaneously self-assemble to form the catalytically inactive apoenzyme. The urease protein depicted shows three copies of each subunit and is adapted from the crystal structure of the urease ( ). The known molecular size of urease (550 kDa) would require two of the depicted protein structures to be associated in some manner ( ). This arrangement has not yet been solved. Accessory genes and encode accessory proteins UreE, UreF, UreG, and UreH, which, by analogy to homologs of other species, serve to insert nickel ions (Ni) into the apoenzyme in an energy-requiring reaction ( ). UreE is a nickel-binding dimer. UreG carries a GTP-binding site. The gene is proposed to encode a urea-specific pore in the inner membrane that opens at low pH to allow passage of urea and closes at high pH to prevent access of the substrate to cytoplasmic urease ( ). Two nickel ions are coordinated into the active site of each UreB subunit. Thus, each urease contains 12 nickel ions when fully activated. Nickel ions are transported into the cell by NixA, a high-affinity membrane transport protein ( ). Additional backup nickel transport proteins are also likely present. The net result of the interaction of these genes and proteins is a catalytically active urease. (Figure designed by David McGee.)

Citation: Mobley H. 2001. Urease, p 179-191. In Mobley H, Mendz G, Hazell S (ed), . ASM Press, Washington, DC. doi: 10.1128/9781555818005.ch16
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Image of Figure 4
Figure 4

Topological model of NixA in the cytoplasmic membrane. The amino acid sequence of NixA is presented in single-letter code. Boxed regions indicate transmembrane domains. Filled black diamonds indicate the location of PhoA and LacZ reporter fusions by number (from amino terminus) of the last NixA amino acid residue prior to the fusion junction; enzymatic activity of reporter fusions were used to predict the topology ( ). Circled residues indicate conserved motifs (among known nickel transporters) in helices II and III, plus six additional transport-critical residues. (Reprinted with permission from reference .)

Citation: Mobley H. 2001. Urease, p 179-191. In Mobley H, Mendz G, Hazell S (ed), . ASM Press, Washington, DC. doi: 10.1128/9781555818005.ch16
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References

/content/book/10.1128/9781555818005.chap16
1. Akada, J. K.,, M. Shirae,, H. Takeuchi,, M. Tsuda,, and T. Nakazawa. 2000. Identification of the urease operon in Helicobacter pylori and its control by mRNA decay in response to pH. Mol. Microbiol. 36:10711084.
2. Angelakopoulos, H.,, and E. L. Hohmann. 2000. Pilot study of phoP/phoQ-deleted Salmonella enterica serovar Typhimurium expressing Helicobacter pylori urease in adult volunteers. Infect, Immun. 68:21352141.
3. Austin, J. W.,, P. Doig,, M. Stewart,, and T. J. Trust. 1991. Macromolecular structure and aggregation states of Helicobacter pylori urease. J. Bacteriol. 173:56635667.
4. Bamford, K. B.,, J. Bickley,, J. S. Collins,, B. T. Johnston,, S. Potts,, V. Boston,, R. J. Owen,, and J. M. Sloan. 1993. Helicobacter pylori: comparison of DNA fingerprints provides evidence for intrafamilial infection. Gut 34:13481350.
5. Bauerfeind, P.,, R. Garner,, B. E. Dunn,, and H. L. T. Mobley. 1997. Synthesis and activity of Helicobacter pylori urease and catalase at low pH. Gut 40:2530.
6. Bauerfeind, P.,, R. M. Garner,, and H. L. T. Mobley. 1996. Allelic exchange mutagenesis of nixa in Helicobacter pylori results in reduced nickel transport and urease activity. Infect. Immun. 64:28772880.
7. Bell, G. D.,, J. Weil,, G. Harrison,, A. Morden,, P. H. Jones,, P. N. Gant,, J. E. Trowell,, A. K. Yoong,, T. K. Daneshmend,, and R. F. Logan. 1987. 14C-urea breath analysis, a non-invasive test for Campylobacter pylori in the stomach. Lancet i: 13671368.
8. Bijlsma, J. J.,, C. M. Vandenbroucke-Grauls,, S. H. Phadnis,, and J. G. Kusters. 1999. Identification of virulence genes of Helicobacter pylori by random insertion mutagenesis. Infect. Immun. 67:24332440.
9. Blanchard, A. 1990. Ureaplasma urealyticum urease genes; use of a UGA tryptophan codon. Mol. Microbiol. 4:669678.
10. Clayton, C. L.,, H. Kleanthous,, P. J. Coates,, D. D. Morgan,, and S. Tabaqchali. 1992. Sensitive detection of Helicobacter pylori by using polymerase chain reaction.J. Clin. Microbiol. 30:192200.
11. Clayton, C. L.,, H. Kleanthous,, D. D. Morgan,, L. Puckey,, and S. Tabaqchali. 1993. Rapid fingerprinting of Helicobacter pylori by polymerase chain reaction and restriction fragment length polymorphism analysis. J. Clin. Microbiol. 31:14201425.
12. Clayton, C.,, H. Kleanthous,, and S. Tabaqchali. 1991. Detection and identification of Helicobacter pylori by the polymerase chain reaction. J. Clin. Pathol. 44:515516.
13. Clayton, C. L.,, M.J. Pallen,, H. Kleanthous,, B. W. Wren,, and S. Tabaqchali. 1990. Nucleotide sequence of two genes from Helicobacter pylori encoding for urease subunits. Nucleic Acids Res. 18:362.
14. Corthesy-Theulaz, I.,, N. Porta,, M. Glauser,, E. Saraga,, A.-C. Vaney,, R. Haas,, J.-P. Kraehenbuhl,, A. L. Blum,, and P. Michetti. 1995. Oral immunization with Helicobacter pylori urease b as a treatment against Helicobacter infection. Gastroenterology 109:115121.
15. Courcoux, P.,, C. Freuland,, Y. Piemout,, J. L. Fauchere,, and A. Labigne. 1990. Polymerase chain reaction and direct DNA sequencing as a method for distinguishing between different strains of Helicobacter pylori. Rev. Esp. Enf. Dig. 78(Suppl 1):2930.
16. Cussac, V.,, R. L. Ferrero,, and A. Labigne. 1992. Expression of Helicobacter pylori urease genes in Escherichia coli grown under nitrogen-limiting conditions. J. Bacteriol. 174: 24662473.
17. de Koning-Ward, T. F.,, A. C. Ward,, and R. M. Robins-Browne. 1994. Characterization of the urease-encoding gene complex of Yersinia enterocolitica. Gene 145:2532.
18. Desai, M.,, D. Linton,, R. J. Owen,, and J. Stanley. 1994. Molecular typing of Helicobacter pylori isolates from asymptomatic, ulcer and gastritis patients by urease gene polymorphism. Epidemiol. Infect. 112:151160.
19. DiPetrillo, M. D.,, T. Tibbetts,, H. Kleanthous,, K. P. Killeen,, and E. L. Hohmann. 1999. Safety and immunogenicity of phoPfphoQ-deleted Salmonella typhi expressing Helicobacter pylori urease in adult volunteers. Vaccine 18:449459.
20. Dixon, N. E.,, P. W. Riddles,, C. Gazzola,, R. L. Blakeley,, and B. Zerner. 1980. Jack bean urease (EC 3.5.1.5). V. On the mechanism of action of urease on urea, formamide, acetamide, N-methylurea, and related compounds. Can. J. Biochem. 58:13351344.
21. Dunn, B. E.,, G. P. Campbell,, G. I. Perez-Perez,, and M. J. Blaser. 1990. Purification and characterization of urease from Helicobacter pylori. J. Biol. Chem. 265:94649469.
22. Dunn, B. E.,, R. M. Roop, 2nd,, C.-C. Sung,, S. A. Sharma,, G. I. Perez-Perez,, and M. J. Blaser. 1992. Identification and purification of a cpn60 heat shock protein homolog from Helicobacter pylori. Infect. Immun. 60:19461951.
23. Eaton, K. A.,, C. L. Brooks,, D. R. Morgan,, and S. Krakowka. 1991. Essential role of urease in pathogenesis of gastritis induced by Helicobacter pylori in gnotobiotic piglets. Infect. Immun. 59:24702475.
24. Eaton, K. A.,, and S. Krakowka. 1994. Effect of gastric pH on urease-dependent colonization of gnotobiotic piglets by Helicobacter pylori. Infect. Immun. 62:36043607.
25. Ermak, T. H.,, P. J. Giannasca,, R. Nichols,, G. A. Myers,, J. Nedrud,, R. Weltzin,, C. K. Lee,, H. Kleanthous,, and T. P. Monath. 1998. Immunization of mice with urease vaccine affords protection against Helicobacter pylori infection in the absence of antibodies and is mediated by MHC cless Il-restricted responses. J. Exp. Med. 188:22772288.
26. Evans, D. J., Jr.,, D. G. Evans,, L. Engstrand,, and D. Y. Graham. 1992. Urease-associated heat shock protein of Helicobacter pylori. Infect. Immun. 60:21252127.
27. Evans, D. J., Jr.,, D. G. Evans,, S. S. Kirkpatrick,, and D. S. Graham. 1991. Characterization of the Helicobacter pylori urease and purification of its subunits. Microb. Pathog. 10: 1526.
28. Ferrero, R. L.,, V. Cussac,, P. Courcoux,, and A. Labigne. 1992. Construction of isogenic urease-negative mutants of Helicobacter pylori by allelic exchange. J. Bacteriol. 174: 42124217.
29. Ferrero, R. L.,, J.-M. Thiberge,, M. Huerre,, and A. Labigne. 1994. Recombinant antigens prepared from the urease sub-units of Helicobacter spp.: evidence of protection in a mouse model of gastric infection. Infect. Immun. 62:49814989.
30. Foxall, P. A.,, L.-T. Hu,, and H. L. T. Mobley. 1990. Amplification of the complete urease structural genes from Helicobacter pylori clinical isolates and cosmid gene bank clones. Rev. Esp. Enf. Dig. 78(Suppl. 1):128129.
31. Foxall, P. A.,, L.-T. Hu,, and H. L. T. Mobley. 1992. Use of polymerase chain reaction-amplified Helicobacter pylori urease structural genes for differentiation of isolates. J. Clin. Microbiol. 30:739741.
32. Foxall, P. A.,, L.-T. Hu,, and H. L. T. Mobley. 1991. Detection of Helicobacter pylori urease structural genes by PCR amplification, abstr. 878. Abst. 91st Annual Meet. Am. Soc. Microbiol., 1991. American Society for Microbiology, Washington, D.C.
33. Fulkerson, J. F., Jr.,, R. M. Garner,, and H. L. T. Mobley. 1998. Conserved residues and motifs in the NixA protein of Helicobacter pylori are critical for the high affinity transport of nickel ions. J. Biol. Chem. 273:235241.
34. Fulkerson, J. F., Jr.,, and H. L. Mobley. 2000. Membrane topology of the NixA nickel transporter of Helicobacter pylori: two nickel transport-specific motifs within transmembrane helices II and HI. J. Bacteriol. 182:17221730.
35. Garner, R. G.,, J. F. Fulkerson, Jr.,, and H. L. T. Mobley. 1998. Helicobacter pylori glutamine synthetase lacks features associated with transcriptional and posttranslational regulation. Infect. Immun. 66:18391847.
36. Gatermann, S.,, and R. Marre. 1989. Cloning and expression of Staphylococcus saprophytics urease gene sequences in Staphylococcus carnosus and contribution of the enzyme to virulence. Infect. Immun. 57:29983002.
37. Gilbert, J. V.,, J. Ramakrishna,, F. W. Sunderman, Jr.,, A. Wright,, and A. G. Plaut. 1995. Protein Hpn: cloning and characterization of a histidine-rich metal-binding polypeptide in Helicobacter pylori and Helicobacter mustelae. Infect. Immun. 63:26822688.
38. Gomez-Duarte, O. G.,, D. Bumann,, and T. F. Meyer. 1999. The attenuated Salmonella vaccine approach for the control of Helicobacter pylori-related diseases. Vaccine 17: 16671673.
39. Graham, D. Y.,, P. D. Klein,, D. J. Evans,, L. C. Alpert,, A. R. Opekun,, and T. W. Boutton. 1987. Campylobacter pyloridis detected by the 13C-urea test. Lancet i: 11741177.
40. Griffith, D. P.,, D. M. Musher,, and C. Itin. 1976. Urease: the primary cause of infection-induced urinary stones. Invest. Urol. 13:346350.
41. Hausinger, R. P. 1987. Nickel utilization by microorganisms. Microbiol. Rev. 51:2224.
42. Hawtin, P. R.,, H. T. Delves,, and D. G. Newell. 1991. The demonstration of nickel in the urease of Helicobacter pylori by atomic absorption spectroscopy. FEMS Microbiol. Lett. 77:5154.
43. Herrmann, L.,, D. Schwan,, R. Garner,, H. L. Mobley,, R. Haas,, K. P. Schafer,, and K. Melchers. 1999. Helicobacter pylori cadA encodes an essential Cd(II)-Zn(II)-Co(II) resistance factor influencing urease activity. Mol. Microbiol. 33:524536.
44. Houimel, M.,, J. P. Mach,, I. Corthesy-Theulaz,, B. Corthesy,, and I. Fisch. 1999. New inhibitors of Helicobacter pylori urease holoenzyme selected from phage-displayed peptide libraries. Eur. J. Biochem. 262:774780.
45. Hu, L.-T.,, P. A. Foxall,, R. Russell,, and H. L. T. Mobley. 1992. Purification of recombinant Helicobacter pylori urease apoenzyme encoded by ureA and ureB. Infect. Immun. 60: 26572666.
46. Hu, L.-T.,, and H. L. T. Mobley. 1990. Purification and N-terminal analysis of urease from Helicobacter pylori. Infect. Immun. 58:992998.
47. Hu, L.-T.,, and H. L. T. Mobley. 1993. Expression of catalytically active recombinant Helicobacter pylori urease at wild type levels in Escherichia colt. Infect. Immun. 61:25632569.
48. Hurtado, A.,, and R.J. Owen. 1994. Identification of mixed genotypes in Helicobacter pylori from gastric biopsy tissue by analysis of urease gene polymorphisms. FEMS Immun. Med. Microbiol. 8:307313.
49. Jabri, E.,, M. B. Carr,, R. P. Hausinger,, and P. A. Karplus. 1995. The crystal structure of urease from Klebsiella aero-genes at 2 A resolution. Science 268:9981004.
50. Jabri, E.,, M. H. Lee,, R. P. Hausinger,, and P. A. Karplus. 1992. Preliminary crystallographic studies of ureases from jack bean and from Klebsiella aerogenes. J. Mol. Biol. 227: 934937.
51. Jones, B. D.,, C. V. Lockatell,, D. E. Johnson,, J. W. Warren,, and H. L. T. Mobley. 1990. Construction of a urease-negative mutant of Proteus mirabilis: analysis of virulence in a mouse model of ascending urinary tract infection. Infect. Immun. 58:11201123.
52. Jones, B. D.,, and H. L. T. Mobley. 1988. Proteus mirabilis urease: genetic organization, regulation, and expression of structural genes. J. Bacteriol. 170:33423349.
53. Jones, B. D.,, and H. L. T. Mobley. 1989. Proteus mirabilis urease: nucleotide sequence determination and comparison with jack bean urease. J. Bacteriol. 171:64146422.
54. Krishnamurthy, P.,, M. Parlow,, J. B. Zitzer,, N. B. Vakil,, H. L. T. Mobley,, M. Levy,, S. H. Phadnis,, and B. E. Dunn. 1998. Helicobacter pylori containing only cytoplasmic urease is susceptible to acid. Infect. Immun. 66:50605066.
55. Labigne A.,, V. Cussac,, and P. Courcoux. 1991. Shuttle cloning and nucleotide sequences of Helicobacter pylori genes responsible for urease activity. J. Bacteriol. 173:19201931.
56. Lee, M. H.,, S. B. Mulrooney,, M. J. Renner,, Y. Markowicz,, and R. P. Hausinger. 1992. Klebsiella aerogenes urease gene cluster: sequence of ureD and demonstration that four accessory genes (ureD, ureE, ureF, ureG) are involved in nickel metallocenter biosynthesis. J. Bacteriol. 174:43244330.
57. Lee, C. K.,, K. Soike,, J. Hill,, K. Georgakopoulos,, T. Tibbitts,, J. Ingrassia,, H. Gray,, J. Boden,, H. Kleanthous,, P. Giannasca,, T. Ermak,, R. Weltzin,, J. Banchard,, and T. P. Monath. 1999. Immunization with recombinant Helicobacter pylori urease decreases colonization levels following experimental infection of rhesus monkeys. Vaccine 17:14931505.
58. Lee, C. K.,, R. Weltzin,, W. D. Thomas, Jr.,, H. Kleanthous,, T. H. Ermak,, G. Soman,, J. E. Hill,, S. K. Ackerman,, and T. P. Monath. 1995. Oral immunization with recombinant Helicobacter pylori urease induces secretory IgA antibodies and protects mice from challenge with Helicobacter felis. J. Infect. Dis. 172:161172.
59. Lopez, C. R.,, R. J. Owen,, and M. Desai. 1993. Differentiation between isolates of Helicobacter pylori by PCR-RFLP analysis of urease A and b genes and comparison with ribosomal RNA gene patterns. FEMS Microbiol. Lett. 110:3744.
60. Maeda, M.,, M. Hidaka,, A. Nakamura,, H. Masaki,, and T. Uozumi. 1994. Cloning, sequencing, and expression of thermophilic Bacillus sp. strain TB-90 urease gene complex in Escherichia coli. J. Bacteriol. 176:432442.
61. Marshall, B. J.,, J. R. Warren,, G. J. Francis,, S. R. Langton,, C. S. Goodwin,, and E. D. Blincow. 1987. Rapid urease test in the management of Campylobacter pyloridis-associated gastritis. Am. J. Gastroenterol. 82:200210.
62. Martin, P. R.,, and R. P. Hausinger. 1992. Site-directed mutagenesis of the active site cysteine in Klebsiella aerogenes urease. J. Biol. Chem. 267:2002420027.
63. McGee, D. J.,, F. J. Radcliff,, G. L. Mendz,, R. L. Ferrero,, and H. L. T. Mobley. 1999. Helicobacter pylori rocF is required for arginase activity and acid protection in vitro but is not essential for colonization of mice or for urease activity. J. Bacteriol. 181:73147322.
64. McGee, D. J.,, C. A. May,, R. M. Garner,, J. M. Himpsl,, and H. L. T. Mobley. 1999. Isolation of Helicobacter pylori genes that modulate urease activity. J. Bacteriol. 181:24772484.
65. McNulty, C. A. M.,, and R. Wise. 1985. Rapid diagnosis of Campylobacter-associated gastritis. Lancet i:1443.
66. Melchers, K.,, T. Weitzenegger,, A. Buhmann,, W. Steinhilber,, G. Sachs,, and K. Schafer. 1996. Cloning and membrane topology of a P type ATPase from Helicobacter pylori. J. Biol. Chem. 271:446457.
67. Michetti, P.,, I. Corthesy-Theulaz,, C. Davin,, R. Haas,, A.-C. Vaney,, M. Heitz,, J. Bille,, J.-P. Kraehenbuhl,, E. Saraga,, and A. L. Blum. 1994. Immunization of BALB/c mice against Helicobacter felis infection with Helicobacter pylori urease. Gastroenterology 107:10021011.
68. Michetti, P.,, C. Kreiss,, K. L. Kotloff,, N. Porta,, J. L. Blanco,, D. Bachmann,, M. Herranz,, P. F. Saldinger,, I. Corthesy-Theulaz,, G. Losonsky,, R. Nichols,, J. Simon,, M. Stolte,, S. Acker-man,, T. P. Monath,, and A. L. Blum. 1999. Oral immunization with urease and Escherichia coli heat-labile enterotoxin is safe and immunogenic in Helicobacter pylori-infected adults. Gastroenterology 116:804812.
69. Mobley, H. L. T.,, M. J. Cortesia,, L. E. Rosenthal,, and B. D. Jones. 1988. Characterization of urease from Campylobacter pylori. J. Clin. Microbiol. 26:831836.
70. Mobley, H. L. T.,, R. E. Garner,, and P. Bauerfeind. 1995. Helicobacter pylori nickel transport gene nixA: synthesis of catalytically active urease in E. coli independent of growth conditions. Mol. Microbiol. 16:97109.
71. Mobley, H. L. T.,, M. D. Island,, and R. P. Hausinger. 1995. Molecular biology of microbial ureases. Microbiol. Rev. 59: 451480.
72. Moore, R. A.,, A. Kureishi,, S. Wong,, and L. E. Bryan. 1993. Categorization of clinical isolates of Helicobacter pylori on the basis of restriction digest analysis of PCR-amplified ureC genes. J. Clin. Microbiol. 31:13341335.
73. Mulrooney, S. B.,, and R. P. Hausinger. 1990. Sequence of the Klebsiella aerogenes urease genes and evidence for accessory proteins facilitating nickel incorporation. J. Bacterial. 172: 58375843.
74. Myers, G. A.,, T. H. Ermak,, K. Georgakopoulos,, T. Tibbitts,, J. Ingrassia,, H. Gray,, H. Kleanthous,, C. K. Lee,, and T. P. Monath. 1999. Oral immunization with recombinant Helicobacter pylori urease confers long-lasting immunity against Helicobacter felis infection. Vaccine 17:13941403.
75. Neyrolles, O.,, S. Ferris,, N. Behbahani,, L. Montagnier,, and A. Blanchard. 1996. Organization of Ureaplasma urealyticum urease gene cluster and expression in a suppressor strain of Escherichia coli. J. Bacteriol. 178:647655.
76. Nicholson, E. B.,, E. A. Concaugh,, P. A. Foxall,, M. D. Island,, and H. L. T. Mobley. 1993. Proteus mirabilis urease: transcriptional regulation by ureR. J. Bacteriol. 175:465473.
77. Nolan, K.,, D. J. McGee,, H. M. Mitchell,, T. Kolesnikow,, J. M. Harro,, J. O'Rourke,, J. E. Wilson,, N. D. Moss,, H. L. T. Mobley,, and A. Lee. In vivo behaviour of Helicobacter pylori SSI nix A mutant with reduced urease activity. Submitted for publication.
78. Owen, R. J.,, J. Bickley,, A. Hurtado,, A. Fraser,, and R. E. Pounder. 1994. Comparison of PCR-based restriction length polymorphism analysis of urease genes with rRNA gene profiling for monitoring Helicobacter pylori infections in patients on triple therapy. J. Clin. Microbiol. 32:12031210.
79. Pappo, J.,, W. D. Thomas, Jr.,, Z. Kabok,, N. S. Taylor,, J. C. Murphy,, and J. G. Fox. 1995. Effect of oral immunization with recombinant urease on murine Helicobacter felis gastritis. Infect. Intmun. 63:12461252.
80. Park, I.-S.,, and R. P. Hausinger. 1993. Site directed mutagenesis of Klebsiella aerogenes urease: identification of histidine residues that appear to function in nickel ligation, substrate binding, and catalysis. Protein Sci. 2:10341041.
81. Park, I.-S.,, and R. P. Hausinger. 1995. Requirement of CO2 for in vitro assembly of the urease nickel metallocenter. Science 267:11561158.
82. Phadnis, S. H.,, M. H. Parlow,, M. Levy,, D. liver,, C. M. Caulkins,, J. B. Connors, andB. E. Dunn. 1996. Surface localization of Helicobacter pylori urease and a heat shock protein homolog requires bacterial autolysis. Infect. Immun. 64: 905912.
83. Reitzer, L. J.,, and B. Magasanik,. 1987. Ammonia assimilation and the biosynthesis of glutamine, glutamate, aspartate, asparagine, L-alanine, and D-alanine, p. 302320. In F. C. Neidhardt (ed.), Escherichia coli and Salmonella typhimurium: Cellular and Molecular Biology, 1st ed. American Society for Microbiology, Washington, D.C.
84. Rektorschek, M.,, A. Buhmann,, D. Weeks,, D. Schwan,, K. W. Bensch,, S. Eskandari,, D. Scott,, G. Sachs,, and K. Melchers. 2000. Acid resistance of Helicobacter pylori depends on the Urel membrane protein and an inner membrane proton barrier. Mol. Microbiol. 36:141152.
85. Riddles, P. W.,, V. Whan,, R. L. Blakeley,, and B. Zerner. 1991. Cloning and sequencing of a jack bean urease-encoding cDNA. Gene 108:265267.
86. Rokita, E.,, A. Makristathis,, A. M. Hirschi,, and M. L. Rotter. 2000. Purification of surface-associated urease from Helicobacter pylori. J. Chromatogr. B. Biomed. Sci. Appl. 737: 203212.
87. Sato, T.,, M. A. Fujino,, Y. Kojima,, H. Ohtsuka,, M. Ohtaka,, K. Kubo,, T. Nakamura,, A. Morozumi,, M. Nakamura,, and H. Hosaka. 1999. Endoscopic urease sensor system for detecting Helicobacter pylori on gastric mucosa. Gastrointest. Endosc. 49:3238.
88. Scott, D. R.,, E. A. Marcus,, D. L. Weeks,, A. Lee,, K. Melchers,, and G. Sachs. 2000. Expression of the Helicobacter pylori urel gene is required acidic pH activation of cytoplasmic urease. Infect. Immun. 68:470477.
89. Scott, D. R.,, D. Weeks,, C. Hong,, S. Postius,, K. Melchers,, and G. Sachs. 1998. The role of internal urease in acid resistance and Helicobacter pylori. Gastroenterology 114:5870.
90. Shirai, M.,, R. Fujinaga,, J. K. Akada,, and T. Nakazawa. 1999. Activation of Helicobacter pylori ureA promoter by a hybrid Escherichia coli-H. pylori rpoD gene in E. coli. Gene239: 351359.
91. Skouloubris, S.,, J. M. Thiberge,, A. Labigne,, and H. De Reuse. 1998. The Helicobacter pylori Urel protein is not involved in urease activity but is essential for bacterial survival in vivo. Infect. Immun. 66:45174521.
92. Skurnik, M.,, S. Batsford,, A. Mertz,, E. Schiltz,, and P. Toivanen. 1993. The putative arthritogenic cationic 19-kilodalton antigen of Yersinia enterocolitica is a urease β-subunit. Infect. Immun. 61:24982504.
93. Solnick, J. V.,, D. R. Canfield,, L. M. Hansen,, and S. Z. Torabian. 2000. Immunization with recombinant Helicobacter pylori urease in specific-pathogen-free rhesus monkeys (Macaca mulatta). Infect. Immun. 68:25602565.
94. Sriwanthana, B.,, M. D. Island,, and H. L. T. Mobley. 1993. Sequence of the Proteus mirabilis urease accessory gene ureG. Gene 129:103106.
95. Suerbaum, S.,, J.-M. Thiberge,, I. Kansau,, R. L. Ferrero,, and A. Labigne. 1994. Helicobacter pylori hspA-hspB heat-shock gene cluster: nucleotide sequence, expression, putative function and imunogenicity. Mol. Microbiol. 14:959974.
96. Szczebara, F.,, L. Dhaenens,, S. Armand,, and M. O. Husson. 1999. Regulation of the transcription of genes encoding different virulence factors in Helicobacter pylori by free iron. FEMS Microbiol. Lett. 175:165170.
97. Takahashi, S.,, H. Igarashi,, K. Nakamura,, N. Masubuchi,, S. Saltos,, T. Aoyagi,, T. Itoh,, and I. Hirata. 1993. Helicobacter pylori urease activity—comparative study between urease positive and urease negative strain. Jpn. J. Clin. Med. 51: 31493153.
98. Tsuda, M.,, M. Karita,, M. G. Morshed,, K. Okita,, and T. Nakasaki. 1994. A urease-negative mutant of Helicobacter pylori constructed by allelic exchange mutagenesis lacks the ability to colonize the nude mouse stomach. Infect. Immun. 62:35863589.
99. Turbett, G. R.,, P. B. Hoj,, R. Home,, and B. J. Mee. 1992. Purification and characterization of the urease enzymes of Helicobacter species from humans and animals. Infect. Immun. 60:52595266.
100. van Zwet, A. A.,, J. C. Thijs,, A. M. D. Kooistra-Smid,, J. Schirm,, and J. A. M. Snijder. 1993. Sensitivity of culture compared with that of polymerase chain reaction for detection of Helicobacter pylori from antral biopsy specimens. J. Clin. Microbiol. 31:19181920.
101. Weeks, D. L.,, S. Eskandara,, D. R. Scott,, and G. Sachs. 2000. A H+-gated urea channel: the link between Helicobacter pylori urease and gastric colonization. Science 287:482485.
102. Westblom, T. U.,, S. Phadnis,, P. Yang,, and S. J. Czinn. 1993. Diagnosis of Helicobacter pylori infection by means of a polymerase chain reaction assay for gastric juice aspirates. Clin. Infect. Dis. 16:367371.

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