Stolz, J and Vielreicher, M (2003) Tpn1p, the plasma membrane vitamin B-6 transporter of Saccharomyces cerevisiae. JOURNAL OF BIOLOGICAL CHEMISTRY, 278 (21). pp. 18990-18996. ISSN 0021-9258, 1083-351X
Full text not available from this repository. (Request a copy)Abstract
Pyridoxine (PN) is a metabolic precursor of pyridoxal phosphate that functions as a cofactor of many enzymes in amino acid metabolism. PN, pyridoxal, and pyridoxamine are collectively referred to as vitamin B-6, and mammalian organisms depend on its uptake from the diet. In addition to the ability to use extracellular vitamin B-6, most unicellular organisms are also capable of synthesizing PN to generate pyridoxal phosphate. Here, we report the isolation of Saccharomyces cerevisiae mutants that have lost the ability to transport PN across the plasma membrane. We used these mutants to isolate TPN1, the first known gene encoding a transport protein for vitamin B-6. Tpn1p is a member of the purine-cytosine permease family within the major facilitator superfamily. The protein functions as a proton symporter, localizes to the plasma membrane, and has high affinity for PN. TPN1 mutants lost the ability to utilize extracellular PN, pyridoxal, and pyridoxamine, showing that there is no other transporter for vitamin B-6 encoded in the genome. Amino acid substitutions that led to a loss of Tpn1p function localized to transmembrane domain 4 within the 12-transmembrane domain protein. Moreover, expression of TPN1 was regulated and increased with decreasing concentrations of vitamin B-6 in the medium. We also provide evidence that of the highly conserved SNZ and SNO genes in S. cerevisiae, only the protein encoded by SNZ1 is required for vitamin B-6 biosynthesis.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | PURINE-CYTOSINE PERMEASE; GENE FAMILIES; YEAST; BIOSYNTHESIS; PYRIDOXINE; PROTEIN; SEQUENCE; RESISTANCE; EXPRESSION; GENOME; |
| Subjects: | 500 Science > 500 Natural sciences & mathematics |
| Divisions: | Biology, Preclinical Medicine > Institut für Pflanzenwissenschaften > Lehrstuhl für Zellbiologie und Pflanzenphysiologie (Prof. Dr. Klaus Grasser) |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 18 May 2021 06:32 |
| Last Modified: | 18 May 2021 06:32 |
| URI: | https://pred.uni-regensburg.de/id/eprint/38989 |
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