The role of internal urease in acid resistance of Helicobacter pylori

Gastroenterology
D R ScottG Sachs

Abstract

The relative role of internal urease for acid protection of Helicobacter pylori is unknown. The aim of this study was to determine the comparative importance of internal and external urease under acidic conditions. The pH optimum and measured Michaelis constant for urea of external urease and urease in intact bacteria at different medium pH (pHout) were measured using 14CO2 release from 14C-urea. The effect of urea on membrane potential and bacterial cytoplasmic pH was measured at different fixed pHout. 35S-methionine labeling and sodium dodecyl sulfate-polyacrylamide gel electrophoresis of labeled proteins in the organism and medium measured protein synthesis at different pHout and mechanisms of urease externalization. External urease had activity between pH 5.0 and 8.5 and internal urease between pHout 2.5 and 6.5, and its Michaelis constant at pHout 7.5 was 300 mmol/L but at pHout 4.5 was 0.5 mmol/L, similar to free urease. The addition of 5 mmol/L urea to bacteria at fixed pHout from 3.0 to 6.0 elevated potential to about -105 mV and periplasmic pH to about pH 6.2. Protein synthesis occurred mainly between pH 6.5 and 8.0, and urease activity resulted in increased protein synthesis at acidic pH. The labeling pattern of intra...Continue Reading

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Citations

Feb 1, 2007·The Journal of Membrane Biology·G SachsD R Scott
Apr 6, 2004·Journal of Theoretical Biology·Ian M Joseph, Denise Kirschner
Dec 21, 2000·Trends in Pharmacological Sciences·G SachsK Melchers
Oct 29, 2002·Journal of Microbiological Methods·Ramon de JongeJohannes G Kusters
Oct 13, 2000·Gastroenterology Clinics of North America·M F Go, S E Crowe
Feb 1, 2003·Research in Microbiology·Marina Mollenhauer-RektorschekKlaus Melchers
Feb 5, 2002·Trends in Microbiology·G SachsK Melchers
Apr 26, 2002·Trends in Microbiology·George SachsKlaus Melchers
Jun 24, 2000·Microbes and Infection·R A Burne, Y Y Chen
Feb 9, 2002·Current Opinion in Microbiology·D Scott Merrell, Andrew Camilli
May 14, 1999·Current Opinion in Microbiology·J W Foster
Sep 1, 1999·Alimentary Pharmacology & Therapeutics·A LeodolterP Malfertheiner
Mar 29, 2000·Alimentary Pharmacology & Therapeutics·V SavarinoS Vigneri
Nov 9, 2000·Alimentary Pharmacology & Therapeutics·G SachsK Melchers
Jul 10, 2001·Molecular Microbiology·D L Weeks, G Sachs
Oct 7, 2006·Current Opinion in Gastroenterology·K T Wilson, G T Fantry
Oct 7, 2006·Current Opinion in Gastroenterology·D J McGee, H L Mobley
Nov 25, 2000·Microbiology and Immunology·F C IcatloY Kodama
Feb 3, 2005·Journal of Gastroenterology and Hepatology·Geoffrey M MatthewsRoss N Butler
Jul 29, 2005·Journal of Gastroenterology and Hepatology·Chander M PathakKrishan L Khanduja
Jul 22, 2009·Antimicrobial Agents and Chemotherapy·Morris O MakobongoD Scott Merrell
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Aug 14, 2001·Infection and Immunity·C S BeckwithL K Riley
Jan 18, 2002·Infection and Immunity·Jetta J E BijlsmaJohannes G Kusters
Jan 18, 2002·Infection and Immunity·Kylie J NolanAdrian Lee
Sep 23, 2003·Infection and Immunity·Yi WenGeorge Sachs
May 23, 2003·Infection and Immunity·D Scott MerrellStanley Falkow
Aug 7, 2012·Journal of Bacteriology·Elizabeth A MarcusDavid R Scott
Jul 3, 2004·Journal of Bacteriology·Karen E BeenkenMark S Smeltzer

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