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UPS1 and UPS2 from Arabidopsis mediate high affinity transport of uracil and 5-fluorouracil.

Schmidt, Anja and Su, Yan-Hua and Kunze, Reinhard and Warner, Susan and Hewitt, Matthew and Slocum, Robert D. and Ludewig, Uwe and Frommer, Wolf B. and Desimone, Marcelo :
UPS1 and UPS2 from Arabidopsis mediate high affinity transport of uracil and 5-fluorouracil.
In: The Journal of biological chemistry, 279 (43) pp. 44817-24. ISSN 0021-9258
[Article] , (2004)

Abstract

Salvage pathways play an important role in providing nucleobases to cells, which are unable to synthesize sufficient amounts for their needs. Cellular uptake systems for pyrimidines have been described, but in higher eukaryotes, transporters for thymine and uracil have not been identified. Two plant transporters, AtUPS1 and PvUPS1, were recently identified as transporters for allantoin in Arabidopsis and French bean, respectively. However, Arabidopsis, in contrast to tropical legumes, uses mainly amino acids for long distance transport. Allantoin transport has not been described in the Brassicaceae. Thus, the physiological substrates of ureide permease (UPS) transporters in Arabidopsis may be compounds structurally related to allantoin. A detailed analysis of the substrate specificities of two members of the AtUPS family shows that AtUPS1 and AtUPS2 mediate high affinity uracil and 5-fluorouracil (a toxic uracil analogue) transport when expressed in yeast and Xenopus oocytes. Consistent with a function during germination and early seedling development, AtUPS1 expression is transiently induced during the early stages of seedling development followed by up-regulation of AtUPS2 expression. Arabidopsis ups2 insertion mutants and ups1 lines, in which transcript levels were reduced by post-transcriptional gene silencing, are more tolerant to 5-fluorouracil as compared with wild type plants. The results suggest that in Arabidopsis UPS transporters are the main transporters for uracil and potentially other nucleobases, whereas during evolution legumes may have taken advantage of the low selectivity of UPS proteins for long distance transport of allantoin.

Item Type: Article
Erschienen: 2004
Creators: Schmidt, Anja and Su, Yan-Hua and Kunze, Reinhard and Warner, Susan and Hewitt, Matthew and Slocum, Robert D. and Ludewig, Uwe and Frommer, Wolf B. and Desimone, Marcelo
Title: UPS1 and UPS2 from Arabidopsis mediate high affinity transport of uracil and 5-fluorouracil.
Language: English
Abstract:

Salvage pathways play an important role in providing nucleobases to cells, which are unable to synthesize sufficient amounts for their needs. Cellular uptake systems for pyrimidines have been described, but in higher eukaryotes, transporters for thymine and uracil have not been identified. Two plant transporters, AtUPS1 and PvUPS1, were recently identified as transporters for allantoin in Arabidopsis and French bean, respectively. However, Arabidopsis, in contrast to tropical legumes, uses mainly amino acids for long distance transport. Allantoin transport has not been described in the Brassicaceae. Thus, the physiological substrates of ureide permease (UPS) transporters in Arabidopsis may be compounds structurally related to allantoin. A detailed analysis of the substrate specificities of two members of the AtUPS family shows that AtUPS1 and AtUPS2 mediate high affinity uracil and 5-fluorouracil (a toxic uracil analogue) transport when expressed in yeast and Xenopus oocytes. Consistent with a function during germination and early seedling development, AtUPS1 expression is transiently induced during the early stages of seedling development followed by up-regulation of AtUPS2 expression. Arabidopsis ups2 insertion mutants and ups1 lines, in which transcript levels were reduced by post-transcriptional gene silencing, are more tolerant to 5-fluorouracil as compared with wild type plants. The results suggest that in Arabidopsis UPS transporters are the main transporters for uracil and potentially other nucleobases, whereas during evolution legumes may have taken advantage of the low selectivity of UPS proteins for long distance transport of allantoin.

Journal or Publication Title: The Journal of biological chemistry
Volume: 279
Number: 43
Divisions: 10 Department of Biology > Plant Nutrition and Biomass
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10 Department of Biology
Date Deposited: 16 Mar 2010 14:12
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