Disease relevance of ATUPS1

• After infection with Pseudomonas syringae or Botrytis cinerea, the expression of genes regulated by both the salicylic acid and jasmonic acid/ethylene pathways is reduced in ups1 compared with wild type [1].

High impact information on ATUPS1

• Transport of (14)C-labeled allantoin by AtUPS1 in yeast exhibited saturation kinetics (K(m) approximately 52 microM), was dependent on Glc and a proton gradient, and was stimulated by acidic pH [2].
• In plants, AtUPS1 gene expression was dependent on the nitrogen source [2].
• Protons are cosubstrates in allantoin transport by AtUPS1, as demonstrated by expression in Xenopus laevis oocytes [2].
• Therefore, AtUPS1 presumably is involved in the uptake of allantoin and other purine degradation products when primary sources are limiting [2].
• AtUPS1 transports uric acid and xanthine, besides allantoin, but not adenine [2].

Biological context of ATUPS1

• AtUPS1 belongs to a novel superfamily of plant membrane proteins with five open reading frames in Arabidopsis (identity, 64 to 82%) [2].
• 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 [3].
• 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 [3].
• 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 [3].
• Camalexin accumulation in ups1 is greatly reduced after infection with these two pathogens, as well as after amino acid starvation or oxidative stress [1].

Anatomical context of ATUPS1

• In contrast, untagged AtUPS1 is rapidly delivered to plasma membrane, where it remains in stable form [4].

Associations of ATUPS1 with chemical compounds

• UPS1 and UPS2 from Arabidopsis mediate high affinity transport of uracil and 5-fluorouracil [3].
• 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 [3].
• We report the characterization of an Arabidopsis thaliana mutant, ups1, isolated on the basis of reduced expression of phosphoribosylanthranilate transferase, a tryptophan biosynthetic enzyme. ups1 also exhibits defects in a wide range of defence responses [1].

References