Please use this identifier to cite or link to this item:
https://olympias.lib.uoi.gr/jspui/handle/123456789/22654Full metadata record
| DC Field | Value | Language |
|---|---|---|
| dc.contributor.author | Karena, E. | en |
| dc.contributor.author | Frillingos, S. | en |
| dc.date.accessioned | 2015-11-24T19:25:47Z | - |
| dc.date.available | 2015-11-24T19:25:47Z | - |
| dc.identifier.issn | 1083-351X | - |
| dc.identifier.uri | https://olympias.lib.uoi.gr/jspui/handle/123456789/22654 | - |
| dc.rights | Default Licence | - |
| dc.subject | Amino Acid Substitution | en |
| dc.subject | Biological Transport, Active/physiology | en |
| dc.subject | Escherichia coli/*chemistry/genetics/metabolism | en |
| dc.subject | Escherichia coli Proteins/*chemistry/genetics/metabolism | en |
| dc.subject | Membrane Transport Proteins/*chemistry/genetics/metabolism | en |
| dc.subject | *Models, Molecular | en |
| dc.subject | Mutation, Missense | en |
| dc.subject | Protein Structure, Secondary | en |
| dc.subject | Structural Homology, Protein | en |
| dc.subject | Xanthine/*chemistry/metabolism | en |
| dc.title | The role of transmembrane segment TM3 in the xanthine permease XanQ of Escherichia coli | en |
| heal.type | journalArticle | - |
| heal.type.en | Journal article | en |
| heal.type.el | Άρθρο Περιοδικού | el |
| heal.identifier.primary | 10.1074/jbc.M111.299164 | - |
| heal.identifier.secondary | http://www.ncbi.nlm.nih.gov/pubmed/21917919 | - |
| heal.identifier.secondary | http://www.jbc.org/content/286/45/39595 | - |
| heal.language | en | - |
| heal.access | campus | - |
| heal.recordProvider | Πανεπιστήμιο Ιωαννίνων. Σχολή Επιστημών Υγείας. Τμήμα Ιατρικής | el |
| heal.publicationDate | 2011 | - |
| heal.abstract | The xanthine permease XanQ of Escherichia coli is used as a study prototype for function-structure analysis of the ubiquitous nucleobase-ascorbate transporter (NAT/NCS2) family. Our previous mutagenesis study of polar residues of XanQ has shown that Asn-93 at the middle of putative TM3 is a determinant of substrate affinity and specificity. To study the role of TM3 in detail we employed Cys-scanning mutagenesis. Using a functional mutant devoid of Cys residues (C-less), each amino acid residue in sequence 79-107 (YGIVGSGLLSIQSVNFSFVTVMIALGSSM) including TM3 (underlined) and flanking sequences was replaced individually with Cys. Of 29 single-Cys mutants, 20 accumulate xanthine to 40-110% of the steady state observed with C-less, six (S88C, F94C, A102C, G104C, S106C) accumulate to low levels (10-30%) and three (G83C, G85C, N93C) are inactive. Extensive mutagenesis reveals that Gly-83 and, to a lesser extent, Gly-85, are crucial for expression in the membrane. Replacements of Asn-93 disrupt affinity (Thr) or permit recognition of 8-methylxanthine which is not a wild-type ligand (Ala, Ser, Asp) and utilization of uric acid which is not a wild-type substrate (Ala, Ser). Replacements of Phe-94 impair affinity for 2-thio and 6-thioxanthine (Tyr) or 3-methylxanthine (Ile). Single-Cys mutants S84C, L86C, L87C, and S95C are highly sensitive to inactivation by N-ethylmaleimide. Our data reveal that key residues of TM3 cluster in two conserved sequence motifs, (83)GSGLL(87) and (93)NFS(95), and highlight the importance of Asn-93 and Phe-94 in substrate recognition and specificity; these findings are supported by structural modeling on the recently described x-ray structure of the uracil-transporting homolog UraA. | en |
| heal.journalName | J Biol Chem | en |
| heal.journalType | peer-reviewed | - |
| heal.fullTextAvailability | TRUE | - |
| Appears in Collections: | Άρθρα σε επιστημονικά περιοδικά ( Ανοικτά) - ΙΑΤ | |
Files in This Item:
There are no files associated with this item.
This item is licensed under a Creative Commons License
