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Titolo:
Sites of pH regulation of the urea channel of Helicobacter pylori
Autore:
Weeks, DL; Sachs, G;
Indirizzi:
VA Greater Los Angeles Hlth Care Syst, Los Angeles, CA 90073 USA VA Greater Los Angeles Hlth Care Syst Los Angeles CA USA 90073 90073 USA Univ Calif Los Angeles, Los Angeles, CA 90073 USA Univ Calif Los Angeles Los Angeles CA USA 90073 Los Angeles, CA 90073 USA
Titolo Testata:
MOLECULAR MICROBIOLOGY
fascicolo: 6, volume: 40, anno: 2001,
pagine: 1249 - 1259
SICI:
0950-382X(200106)40:6<1249:SOPROT>2.0.ZU;2-E
Fonte:
ISI
Lingua:
ENG
Soggetto:
STREPTOCOCCUS-SALIVARIUS; CAMPYLOBACTER-PYLORI; ACID RESISTANCE; PROTEIN; WATER; TRANSPORTERS; METABOLISM; EXPRESSION; GLYCEROL; OOCYTES;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
30
Recensione:
Indirizzi per estratti:
Indirizzo: Sachs, G VA Greater Los Angeles Hlth Care Syst, Bldg 113,Room 324, Los Angeles, CA 90073 USA VA Greater Los Angeles Hlth Care Syst Bldg 113,Room 324 Los Angeles CA USA 90073
Citazione:
D.L. Weeks e G. Sachs, "Sites of pH regulation of the urea channel of Helicobacter pylori", MOL MICROB, 40(6), 2001, pp. 1249-1259

Abstract

Helicobacter pylori (Hp) and Streptococcus salivarius (Ss) require intrabacterial urease for acid resistance and express a urea channel, UreI. The presence of UreI was shown to increase urea permeability approximate to 300-fold over that of a non-polar ureI deletion mutant. Expression of SsUreI in Xenopus oocytes increased urea uptake pH independently, whereas HpUreI shows an acidic pH dependence, half-maximal at pH 6.0. Mutagenesis of all histidines, aspartates, glutamates and the lysine in the periplasmic domain of HpUreI showed that His-123, His-131, Asp-129, Asp-140, Glu-138 and Lys-132 in the second periplasmic loop (PL2) and His-193 in the C-terminus (Ct) wereimportant for activation of transport. With the exception of a lysine thatwas shown to substitute for His-193 in HpUreI, these charged amino acids are absent in SsUreI. A chimera in which PL1 of HpUreI was replaced by PL1 of SsUreI retained activity at acidic pH and gained partial activity at neutral pH. Exchange of PL2 inactivated transport, whereas exchange of Ct had no effect. Chimeras, in which either PL1 or PL2 of HpUreI replaced those of SsUreI, retained wild-type transport, but replacement of the Ct or both loops inactivated transport. PL1 appears to be important for restricting transport through HpUreI at neutral pH, whereas protonation of three histidines in PL2 and Ct and the presence of three dicarboxylic amino acids in PL2 appears to be necessary to activate HpUreI at acidic pH.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 30/03/20 alle ore 00:51:11