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dc.contributor.authorFrillingos, S.en
dc.contributor.authorKaback, H. R.en
dc.date.accessioned2015-11-24T19:30:21Z-
dc.date.available2015-11-24T19:30:21Z-
dc.identifier.issn0961-8368-
dc.identifier.urihttps://olympias.lib.uoi.gr/jspui/handle/123456789/23076-
dc.rightsDefault Licence-
dc.subjectBiological Transport, Activeen
dc.subjectEscherichia coli/*enzymologyen
dc.subject*Escherichia coli Proteinsen
dc.subjectEthylmaleimide/*chemistryen
dc.subjectLactose/metabolismen
dc.subjectMembrane Transport Proteins/*chemistry/genetics/metabolismen
dc.subject*Monosaccharide Transport Proteinsen
dc.subjectMutagenesis, Site-Directeden
dc.subjectSubstrate Specificityen
dc.subject*Symportersen
dc.titleThe role of helix VIII in the lactose permease of Escherichia coli: II. Site-directed sulfhydryl modificationen
heal.typejournalArticle-
heal.type.enJournal articleen
heal.type.elΆρθρο Περιοδικούel
heal.identifier.primary10.1002/pro.5560060221-
heal.identifier.secondaryhttp://www.ncbi.nlm.nih.gov/pubmed/9041647-
heal.identifier.secondaryhttp://onlinelibrary.wiley.com/store/10.1002/pro.5560060221/asset/5560060221_ftp.pdf?v=1&t=h0by6rc1&s=98eb275c73d2fd163b8455a73520acabb43ab44f-
heal.languageen-
heal.accesscampus-
heal.recordProviderΠανεπιστήμιο Ιωαννίνων. Σχολή Επιστημών Υγείας. Τμήμα Ιατρικήςel
heal.publicationDate1997-
heal.abstractCys-scanning mutagenesis of putative transmembrane helix VIII in the lactose permease of Escherichia coli (Frillingos S. Ujwal ML, Sun J, Kaback HR, 1997, Protein Sci 6:431-437) indicates that, although helix VIII contains only one irreplaceable residue (Glu 269), one face is important for active lactose transport. In this study, the rate of inactivation of each N-ethylmaleimide (NEM)-sensitive mutant is examined in the absence or presence of beta, D-galactopyranosyl 1-thio-beta,D-galactopyranoside (TDG). Remarkably, the analogue affords protection against inactivation with mutants Val 264-->Cys, Gly 268-->Cys, and Asn 272-->Cys, and alkylation of these single-Cys mutants in right-side-out membrane vesicles with [14C]NEM is attenuated by TDG. In contrast, alkylation of Thr 265-->Cys, which borders the three residues that are protected by TDG, is enhanced markedly by the analogue. Furthermore, NEM-labeling in the presence of the impermeant thiol reagent methanethiosulfonate ethylsulfonate demonstrates that ligand enhances the accessibility of position 265 to solvent. Finally, no significant alteration in NEM reactivity is observed for mutant Gly 262-->Cys, Glu 269-->Cys, Ala 273-->Cys, Met 276-->Cys, Phe 277-->Cys, or Ala 279-->Cys. The findings indicate that a portion of one face of helix VIII (Val 264, Gly 268, and Asn 272), which is in close proximity to Cys 148 (helix V), interacts with substrate, whereas another position bordering these residues (Thr 265) is altered by a ligand-induced conformational change.en
heal.journalNameProtein Scien
heal.journalTypepeer-reviewed-
heal.fullTextAvailabilityTRUE-
Appears in Collections:Άρθρα σε επιστημονικά περιοδικά ( Ανοικτά) - ΙΑΤ

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