title: Aquaporin homologues in plants and mammals transport ammonia.
abstract: Using functional complementation and a yeast mutant deficient in ammonium (NH4+) transport (Deltamep1-3), three wheat (Triticum aestivum) TIP2 aquaporin homologues were isolated that restored the ability of the mutant to grow when 2 mM NH4+ was supplied as the sole nitrogen source. When expressed in Xenopus oocytes, TaTIP2;1 increased the uptake of NH4+ analogues methylammonium and formamide. Furthermore, expression of TaTIP2;1 increased acidification of the oocyte-bathing medium containing NH4+ in accordance with NH3 diffusion through the aquaporin. Homology modeling of TaTIP2;1 in combination with site directed mutagenesis suggested a new subgroup of NH3-transporting aquaporins here called aquaammoniaporins. Mammalian AQP8 sharing the aquaammoniaporin signature also complemented NH4+ transport deficiency in yeast.
authors.affiliation: Plant Nutrition Laboratory, Department of Agricultural Sciences, The Royal Veterinary and Agricultural University, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark. tpj@kvl.dk
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Jahn
authors.forename: Anders L B
authors.initials: AL
authors.lastname: Møller
authors.forename: Thomas
authors.initials: T
authors.lastname: Zeuthen
authors.forename: Lars M
authors.initials: LM
authors.lastname: Holm
authors.forename: Dan A
authors.initials: DA
authors.lastname: Klaerke
authors.forename: Brigitte
authors.initials: B
authors.lastname: Mohsin
authors.forename: Werner
authors.initials: W
authors.lastname: Kühlbrandt
authors.forename: Jan K
authors.initials: JK
authors.lastname: Schjoerring
mesh_terms: D000641:Ammonia / Q000378:metabolism*; D000818:Animals; D020346:Aquaporins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001692:Biological Transport; D003001:Cloning, Molecular; D017931:DNA Primers; D005816:Genetic Complementation Test; D016297:Mutagenesis, Site-Directed; D010944:Plants / Q000378:metabolism*
chemical_list: D020346:Aquaporins; D017931:DNA Primers; D000641:Ammonia