A novel superfamily of transporters for allantoin and other oxo derivatives of nitrogen heterocyclic compounds in Arabidopsis.
A wide spectrum of soil heterocyclic nitrogen compounds are potential nutrients for plants. Here, it is shown that Arabidopsis plants are able to use allantoin as sole nitrogen source. By functional complementation of a yeast mutant defective in allantoin uptake, an Arabidopsis transporter, AtUPS1 (Arabidopsis thaliana ureide permease 1), was identified. AtUPS1 belongs to a novel superfamily of plant membrane proteins with five open reading frames in Arabidopsis (identity, 64 to 82%). UPS proteins have 10 putative transmembrane domains with a large cytosolic central domain containing a "Walker A" motif. 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. AtUPS1 transports uric acid and xanthine, besides allantoin, but not adenine. Protons are cosubstrates in allantoin transport by AtUPS1, as demonstrated by expression in Xenopus laevis oocytes. In plants, AtUPS1 gene expression was dependent on the nitrogen source. Therefore, AtUPS1 presumably is involved in the uptake of allantoin and other purine degradation products when primary sources are limiting.
Desimone
Marcelo
M
Plant Physiology, Zentrum für Molekularbiologie der Pflanzen, Auf der Morgenstelle 1, D-72076 Tübingen, Germany. marcelo.desimone@zmbp.uni-tuebingen.de
Catoni
Elisabetta
E
Ludewig
Uwe
U
Hilpert
Melanie
M
Schneider
Anja
A
Kunze
Reinhard
R
Tegeder
Mechthild
M
Frommer
Wolf Bernd
WB
Schumacher
Karin
K
D000481:Allantoin / Q000031:analogs & derivatives / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D001692:Biological Transport; D002250:Carbon Radioisotopes; D003001:Cloning, Molecular; D005260:Female; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D006571:Heterocyclic Compounds / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D026901:Membrane Transport Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D017672:Nitrogen Compounds / Q000378:metabolism*; D009865:Oocytes; D010641:Phenotype; D017386:Sequence Homology, Amino Acid; D014982:Xenopus laevis / Q000235:genetics
D029681:Arabidopsis Proteins; D002250:Carbon Radioisotopes; D006571:Heterocyclic Compounds; D026901:Membrane Transport Proteins; D017672:Nitrogen Compounds; C460110:ureide permease 1, Arabidopsis; D000481:Allantoin