title: Molecular cloning and characterization of a sodium-pump ATPase of the moss Physcomitrella patens.
abstract: Physcomitrella patens grew slowly at 600 mm Na+, pH 6.0, affected by the low water potential but without signs of suffering Na+ toxicity. At pH 8.0, tolerance seemed to be lower but it grew at 200 mm Na+, again without signs of Na+ toxicity. The resistance of Physcomitrella cells to the toxic effects of Na+ can be accounted for by their capacity to keep high K+:Na+ ratios and to extrude Na+ by a system that is not dependent on DeltapH. Physcomitrella expresses two P-type ATPases similar in sequence to fungal ENA-type Na+-ATPases. A functional study in yeast demonstrated that one of these ATPases, PpENA1, is an Na+-pump. We also found that P. patens has a plant-type SOS1 Na+/H+ antiporter. We discuss that Na+-ATPases existed in early land plants but that they were lost during the evolution of bryophytes to flowering plants.
authors: Departamento de Biotecnología, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Politécnica de Madrid, 28040 Madrid, Spain.
authors: Begoña
authors: B
authors: Benito
authors: Alonso
authors: A
authors: Rodríguez-Navarro
mesh_terms: D044002:Bryophyta / Q000145:classification / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development; D003001:Cloning, Molecular; D010802:Phylogeny; D010944:Plants / Q000145:classification / Q000201:enzymology / Q000235:genetics; D012964:Sodium / Q000378:metabolism / Q000494:pharmacology; D000254:Sodium-Potassium-Exchanging ATPase / Q000187:drug effects / Q000235:genetics*
chemical_list: D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase