title: Molecular characterization of PeNhaD1: the first member of the NhaD Na+/H+ antiporter family of plant origin.
abstract: PeNhaD1 encodes a putative Na+/H+ antiporter from the salt-resistant tree Populus euphratica. It is the first characterization of a member of the NhaD type ion transporter family of plant origin. Homology searches revealed its close relation to functionally characterized microbial Na+/H+ antiporters VpNhaD and VcNhaD. Na+/H+ antiporters have proven to play a key role in salt resistance, both in plants and bacteria. Under salt stress transcript levels of PeNhaD1 were maintained only in the salt-resistant P. euphratica, but collapsed in Populus x canescens, a salt-sensitive species. To address the function of PeNhaD1, complementation studies with the salt-sensitive Escherichia coli EP432 mutant strain, lacking activity of the two Na+/H+ antiporters EcNhaA and EcNhaB were carried out. PeNhaD1 was able to restore growth of EP432 under stress imposed by up to 400 mM NaCl demonstrating its protective function. Growth rates of EP432 were always highest at pH 5.5 while growth was suppressed under salt stress at pH 7.0 and pH 8.0 suggesting that the antiporter activity is strongly pH dependent. Element analyses of EP432 cells complemented with PeNhaD1 growing under salt stress showed that salt resistance was correlated with a significant reduction in sodium accumulation. These results suggest that PeNhaD1 might play a role in the salt resistance of P. euphratica.
authors: Institut für Forstbotanik, Georg-August-Universität Göttingen, Büsgenweg 2, 37077, Göttingen, Germany.
authors: Eric A
authors: EA
authors: Ottow
authors: Andrea
authors: A
authors: Polle
authors: Mikael
authors: M
authors: Brosché
authors: Jaakko
authors: J
authors: Kangasjärvi
authors: Pavel
authors: P
authors: Dibrov
authors: Christian
authors: C
authors: Zörb
authors: Thomas
authors: T
authors: Teichmann
mesh_terms: D000222:Adaptation, Physiological; D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005816:Genetic Complementation Test; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D008969:Molecular Sequence Data; D009154:Mutation; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D032107:Populus / Q000187:drug effects / Q000235:genetics*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D012965:Sodium Chloride / Q000494:pharmacology; D017923:Sodium-Hydrogen Exchangers / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D013997:Time Factors
chemical_list: D018076:DNA, Complementary; D010940:Plant Proteins; D017923:Sodium-Hydrogen Exchangers; D012965:Sodium Chloride