Proton/urea cotransporter
From Purdue Genomics Database Facility
- Dominique Loqué (dloque@lbl.gov; Joint BioEnergy Institute, Lawrence Berkeley National laboratory Emeryville, CA 95608, USA)
- Sylvie Lalonde (slalonde@stanford.edu; Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305, USA)
- Wolf B. Frommer (wfrommer@stanford.edu; Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305, USA)
Contents |
Urea transporter gene family
Of all mineral elements required by plants, nitrogen is quantitatively the most important and thus often growth-limiting factor for many plants. Nitrogen is found in many organic compounds such as amino acids, nucleic acid and consequently in proteins, nuclei acids etc. In most soils, nitrogen is heterogeneously distributed and found in various forms such as ammonium, nitrate, urea, amino acids, peptides and water-insoluble fractions (Jackson and Bloom, 1990). Due to the impermeability or poor permeability of the lipid bilayer of the plasma membrane to most of nutrients including nitrogen compounds, uni- and multi-cellular organisms possess various transporters. In 2003 the first plant urea transporter (Dur3) was cloned from Arabidopsis by homology to the yeast transporter (DUR3, YHL016C; ElBerry et al., 1993) and characterized as proton/urea cotransporter by electrophysiology (Liu et al., 2003). In planta characterization showed that AtDUR3 is the major high affinity urea transporter under nitrogen limiting growth condition. (Kojima et al., 2007). DUR3 is not the only entry for urea into the cytosol, few aquaporins from TIP and NOD26 families were shown to be able to facilitate urea transport through the plasma membrane (for review Kojima et al., 2006).
Major findings
- Analysis of Selaginella moellendorffii genome suggests the presence of a unique DUR3 homologue annotated as DUR3 as found in Arabidopsis or rice genome. It seems that many of plant species carry only two copies or less of DUR3, so species might have lost it, for example, BlastP search on poplar genome could not find any homologue. One reason of a very low number of urea transporters could be linked to the urea availability. In fact, since urea is rapidly converted into ammonium in soil and then can be taken up by ammonium transporters (AMTs), only a large availability of urea might have a significant effect on growth meaning it would require only low affinity urea transporter such as aquaporins.
Sequences
- Dur3 sequences lacking the "soluble" part of N-terminus (sequence before the first predicted TM) and the far end of the "soluble" C-terminus (Media:All-Dur3s-C-N.txt).
- Full length of DUR3 before deletion of the termini (Media:All-DUR3s-full.txt).
References
- Jackson LE, Bloom AJ (1990) Root distribution in relation to soil nitrogen availability in field grown tomatoes. Plant Soil. 128: 115-121
- Kojima S, Bohner A, Gassert B, Yuan L, von Wirén N (2007) AtDUR3 represents the major transporter for high-affinity urea transport across the plasma membrane of nitrogen-deficient Arabidopsis roots. Plant J. 52: 30-40
- Kojima S, Bohner A, von Wirén N (2006) Molecular mechanisms of urea transport in plants. J. Membr. Biol. 212: 83-91
- Liu LH, Ludewig U, Frommer WB, von Wirén N (2003) AtDUR3 encodes a new type of high-affinity urea/H+ symporter in Arabidopsis. Plant Cell. 15:790-800
- ElBerry HM, Majumdar ML, Cunningham TS, Sumrada RA, Cooper TG (1993) Regulation of the urea active transporter gene (DUR3) in Saccharomyces cerevisiae. J Bacteriol. 175: 4688-4698
Table of gene numbers
| Gene functions | Gene | Gene used as a query | The number of putative orthologs | ||||
|---|---|---|---|---|---|---|---|
| Arabidopsis thaliana | Oryza sativa | Selaginalla moellendorffii | Physcomitrella patens | Chlamydomonas reinhardtii | |||
| Urea Transport | DUR3 | AtDUR3 (At5g45380) | 1 | 1 | 1 | 2 | 2 |
