The substrate selectivity of YgfU, a uric acid transporter from Escherichia coli
| dc.contributor.author | Papakostas, K. | en |
| dc.contributor.author | Frillingos, S. | en |
| dc.date.accessioned | 2015-11-24T19:24:03Z | |
| dc.date.available | 2015-11-24T19:24:03Z | |
| dc.identifier.issn | 1083-351X | - |
| dc.identifier.uri | https://olympias.lib.uoi.gr/jspui/handle/123456789/22410 | |
| dc.rights | Default Licence | - |
| dc.title | The substrate selectivity of YgfU, a uric acid transporter from Escherichia coli | en |
| heal.abstract | The ubiquitous nucleobase-ascorbate transporter (NAT/NCS2) family includes more than 2,000 members but only 15 have been characterized experimentally. Escherichia coli has 10 members, of which functionally known are the uracil permease UraA and the xanthine permeases XanQ and XanP. Of the remaining members, YgfU is closely related in sequence and genomic locus with XanQ. We analyzed YgfU and showed that it is a proton-gradient dependent, low-affinity (Km 0.5 mM) and high-capacity transporter for uric acid. It also shows a low capacity for transport of xanthine at 37 degrees C but not at 25 degrees C. Based on the set of positions delineated as important from our previous Cys-scanning analysis of permease XanQ, we subjected YgfU to rationally designed site-directed mutagenesis. The results show that the conserved His-37 (TM1), Glu-270 (TM8), Asp-298 (TM9), Gln-318 and Asn-319 (TM10) are functionally irreplaceable, and Thr-100 (TM3) is essential for the uric acid selectivity since its replacement with Ala allows efficient uptake of xanthine. The key role of these residues is corroborated by the conservation pattern and homology modeling on the recently described x-ray structure of permease UraA. In addition, site-specific replacements at TM8 (S271A, M274D, V282S) impair expression in the membrane, V320N (TM10) inactivates, and R327G (TM10) or S426N (TM14) reduces the affinity for uric acid (four-fold increased Km). Our study shows that comprehensive analysis of structure-function relationships in a newly characterized transporter can be accomplished with relatively few site-directed replacements, based on the knowledge available from Cys-scanning mutagenesis of a prototypic homolog. | en |
| heal.access | campus | - |
| heal.fullTextAvailability | TRUE | - |
| heal.identifier.primary | 10.1074/jbc.M112.355818 | - |
| heal.identifier.secondary | http://www.ncbi.nlm.nih.gov/pubmed/22437829 | - |
| heal.identifier.secondary | http://www.jbc.org/content/early/2012/03/21/jbc.M112.355818.full.pdf | - |
| heal.journalName | J Biol Chem | en |
| heal.journalType | peer-reviewed | - |
| heal.language | en | - |
| heal.publicationDate | 2012 | - |
| heal.recordProvider | Πανεπιστήμιο Ιωαννίνων. Σχολή Επιστημών Υγείας. Τμήμα Ιατρικής | el |
| heal.type | journalArticle | - |
| heal.type.el | Άρθρο Περιοδικού | el |
| heal.type.en | Journal article | en |
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