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Homo- and hetero-oligomerization of ammonium transporter-1 NH4 uniporters.

Ludewig, Uwe and Wilken, Stephanie and Wu, Binghua and Jost, Wolfgang and Obrdlik, Petr and El Bakkoury, Mohamed and Marini, Anne-Marie and André, Bruno and Hamacher, Tanja and Boles, Eckhard and von Wirén, Nicolaus and Frommer, Wolf B. :
Homo- and hetero-oligomerization of ammonium transporter-1 NH4 uniporters.
In: The Journal of biological chemistry, 278 (46) pp. 45603-10. ISSN 0021-9258
[Article], (2003)

Abstract

In most organisms, high affinity ammonium uptake is catalyzed by members of the ammonium transporter family (AMT/MEP/Rh). A single point mutation (G458D) in the cytosolic C terminus of the plasma membrane transporter LeAMT1;1 from tomato leads to loss of function, although mutant and wild type proteins show similar localization when expressed in yeast or plant protoplasts. Co-expression of LeAMT1;1 and mutant in Xenopus oocytes inhibited ammonium transport in a dominant negative manner, suggesting homo-oligomerization. In vivo interaction between LeAMT1;1 proteins was confirmed by the split ubiquitin yeast two-hybrid system. LeAMT1;1 is isolated from root membranes as a high molecular mass oligomer, converted to a approximately 35-kDa polypeptide by denaturation. To investigate interactions with the LeAMT1;2 paralog, co-localizing with LeAMT1;1 in root hairs, LeAMT1;2 was characterized as a lower affinity NH4+ uniporter. Co-expression of wild types with the respective G458D/G465D mutants inhibited ammonium transport in a dominant negative manner, supporting the formation of heteromeric complexes in oocytes. Thus, in yeast, oocytes, and plants, ammonium transporters are able to oligomerize, which may be relevant for regulation of ammonium uptake.

Item Type: Article
Erschienen: 2003
Creators: Ludewig, Uwe and Wilken, Stephanie and Wu, Binghua and Jost, Wolfgang and Obrdlik, Petr and El Bakkoury, Mohamed and Marini, Anne-Marie and André, Bruno and Hamacher, Tanja and Boles, Eckhard and von Wirén, Nicolaus and Frommer, Wolf B.
Title: Homo- and hetero-oligomerization of ammonium transporter-1 NH4 uniporters.
Language: English
Abstract:

In most organisms, high affinity ammonium uptake is catalyzed by members of the ammonium transporter family (AMT/MEP/Rh). A single point mutation (G458D) in the cytosolic C terminus of the plasma membrane transporter LeAMT1;1 from tomato leads to loss of function, although mutant and wild type proteins show similar localization when expressed in yeast or plant protoplasts. Co-expression of LeAMT1;1 and mutant in Xenopus oocytes inhibited ammonium transport in a dominant negative manner, suggesting homo-oligomerization. In vivo interaction between LeAMT1;1 proteins was confirmed by the split ubiquitin yeast two-hybrid system. LeAMT1;1 is isolated from root membranes as a high molecular mass oligomer, converted to a approximately 35-kDa polypeptide by denaturation. To investigate interactions with the LeAMT1;2 paralog, co-localizing with LeAMT1;1 in root hairs, LeAMT1;2 was characterized as a lower affinity NH4+ uniporter. Co-expression of wild types with the respective G458D/G465D mutants inhibited ammonium transport in a dominant negative manner, supporting the formation of heteromeric complexes in oocytes. Thus, in yeast, oocytes, and plants, ammonium transporters are able to oligomerize, which may be relevant for regulation of ammonium uptake.

Journal or Publication Title: The Journal of biological chemistry
Volume: 278
Number: 46
Divisions: Biology > Botany > Plant Nutrition and Biomass
Biology > Botany
Biology
Date Deposited: 17 Mar 2010 15:47
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