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Please use this identifier to cite or link to this item: https://olympias.lib.uoi.gr/jspui/handle/123456789/18878
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dc.contributor.authorGeorgopoulou, E.en
dc.contributor.authorMermelekas, G.en
dc.contributor.authorKarena, E.en
dc.contributor.authorFrillingos, S.en
dc.date.accessioned2015-11-24T18:55:26Z-
dc.date.available2015-11-24T18:55:26Z-
dc.identifier.issn1083-351X-
dc.identifier.urihttps://olympias.lib.uoi.gr/jspui/handle/123456789/18878-
dc.rightsDefault Licence-
dc.subjectAlanine/*chemistryen
dc.subjectAmino Acid Motifsen
dc.subjectAmino Acid Sequenceen
dc.subjectAscorbic Acid/*chemistryen
dc.subjectAsparagine/*chemistryen
dc.subjectEscherichia coli/metabolismen
dc.subjectEscherichia coli Proteins/chemistry/*physiologyen
dc.subjectEthylmaleimide/chemistryen
dc.subjectInhibitory Concentration 50en
dc.subjectKineticsen
dc.subjectMesylates/chemistryen
dc.subjectMolecular Sequence Dataen
dc.subjectMutationen
dc.subjectNucleic Acids/chemistryen
dc.subjectNucleobase Transport Proteins/chemistry/*physiologyen
dc.subjectProtein Structure, Secondaryen
dc.subjectPurines/chemistryen
dc.subjectSequence Homology, Amino Aciden
dc.titlePurine substrate recognition by the nucleobase-ascorbate transporter signature motif in the YgfO xanthine permease: ASN-325 binds and ALA-323 senses substrateen
heal.typejournalArticle-
heal.type.enJournal articleen
heal.type.elΆρθρο Περιοδικούel
heal.identifier.primary10.1074/jbc.M110.120543-
heal.identifier.secondaryhttp://www.ncbi.nlm.nih.gov/pubmed/20406814-
heal.identifier.secondaryhttp://www.jbc.org/content/285/25/19422.full.pdf-
heal.languageen-
heal.accesscampus-
heal.recordProviderΠανεπιστήμιο Ιωαννίνων. Σχολή Επιστημών Υγείας. Τμήμα Ιατρικήςel
heal.publicationDate2010-
heal.abstractThe nucleobase-ascorbate transporter (NAT) signature motif is a conserved 11-amino acid sequence of the ubiquitous NAT/NCS2 family, essential for function and selectivity of both a bacterial (YgfO) and a fungal (UapA) purine-transporting homolog. We examined the role of NAT motif in more detail, using Cys-scanning and site-directed alkylation analysis of the YgfO xanthine permease of Escherichia coli. Analysis of single-Cys mutants in the sequence 315-339 for sensitivity to inactivation by 2-sulfonatoethyl methanethiosulfonate (MTSES(-)) and N-ethylmaleimide (NEM) showed a similar pattern: highly sensitive mutants clustering at the motif sequence (323-329) and a short alpha-helical face downstream (332, 333, 336). In the presence of substrate, N325C is protected from alkylation with either MTSES(-) or NEM, whereas sensitivity of A323C to inactivation by NEM is enhanced, shifting IC(50) from 34 to 14 microM. Alkylation or sensitivity of the other mutants is unaffected by substrate; the lack of an effect on Q324C is attributed to gross inability of this mutant for high affinity binding. Site-directed mutants G333R and S336N at the alpha-helical face downstream the motif display specific changes in ligand recognition relative to wild type; G333R allows binding of 7-methyl and 8-methylxanthine, whereas S336N disrupts affinity for 6-thioxanthine. Finally, all assayable motif-mutants are highly accessible to MTSES(-) from the periplasmic side. The data suggest that the NAT motif region lines the solvent- and substrate-accessible inner cavity, Asn-325 is at the binding site, Ala-323 responds to binding with a specific conformational shift, and Gly-333 and Ser-336 form part of the purine permeation pathway.en
heal.journalNameJ Biol Chemen
heal.journalTypepeer-reviewed-
heal.fullTextAvailabilityTRUE-
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