title: TsHKT1;2, a HKT1 homolog from the extremophile Arabidopsis relative Thellungiella salsuginea, shows K(+) specificity in the presence of NaCl.
abstract: Cellular Na(+)/K(+) ratio is a crucial parameter determining plant salinity stress resistance. We tested the function of plasma membrane Na(+)/K(+) cotransporters in the High-affinity K(+) Transporter (HKT) family from the halophytic Arabidopsis (Arabidopsis thaliana) relative Thellungiella salsuginea. T. salsuginea contains at least two HKT genes. TsHKT1;1 is expressed at very low levels, while the abundant TsHKT1;2 is transcriptionally strongly up-regulated by salt stress. TsHKT-based RNA interference in T. salsuginea resulted in Na(+) sensitivity and K(+) deficiency. The athkt1 mutant lines overexpressing TsHKT1;2 proved less sensitive to Na(+) and showed less K(+) deficiency than lines overexpressing AtHKT1. TsHKT1;2 ectopically expressed in yeast mutants lacking Na(+) or K(+) transporters revealed strong K(+) transporter activity and selectivity for K(+) over Na(+). Altering two amino acid residues in TsHKT1;2 to mimic the AtHKT1 sequence resulted in enhanced sodium uptake and loss of the TsHKT1;2 intrinsic K(+) transporter activity. We consider the maintenance of K(+) uptake through TsHKT1;2 under salt stress an important component supporting the halophytic lifestyle of T. salsuginea.
authors.affiliation: Division of Applied Life Science (Brain Korea 21 Program) and Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-701, Korea.
authors.forename: Zahir
authors.initials: Z
authors.lastname: Ali
authors.forename: Hyeong Cheol
authors.initials: HC
authors.lastname: Park
authors.forename: Akhtar
authors.initials: A
authors.lastname: Ali
authors.forename: Dong-Ha
authors.initials: DH
authors.lastname: Oh
authors.forename: Rashid
authors.initials: R
authors.lastname: Aman
authors.forename: Anna
authors.initials: A
authors.lastname: Kropornicka
authors.forename: Hyewon
authors.initials: H
authors.lastname: Hong
authors.forename: Wonkyun
authors.initials: W
authors.lastname: Choi
authors.forename: Woo Sik
authors.initials: WS
authors.lastname: Chung
authors.forename: Woe-Yeon
authors.initials: WY
authors.lastname: Kim
authors.forename: Ray A
authors.initials: RA
authors.lastname: Bressan
authors.forename: Hans J
authors.initials: HJ
authors.lastname: Bohnert
authors.forename: Sang Yeol
authors.initials: SY
authors.lastname: Lee
authors.forename: Dae-Jin
authors.initials: DJ
authors.lastname: Yun
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D019607:Brassicaceae / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism*; D019143:Evolution, Molecular; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D006706:Homeostasis; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010802:Phylogeny; D018517:Plant Roots / Q000235:genetics / Q000502:physiology; D030821:Plants, Genetically Modified / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D011188:Potassium / Q000378:metabolism*; D034622:RNA Interference; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D055051:Salt-Tolerant Plants / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D012964:Sodium / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology*; D013045:Species Specificity; D013379:Substrate Specificity; D027981:Symporters / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D027682:Cation Transport Proteins; C490286:HKT1 protein, Arabidopsis; D027981:Symporters; D012965:Sodium Chloride; D012964:Sodium; D011188:Potassium