title: Characterization of AtCHX17, a member of the cation/H+ exchangers, CHX family, from Arabidopsis thaliana suggests a role in K+ homeostasis.
abstract: The Arabidopsis genome contains many sequences annotated as encoding H(+)-coupled cotransporters. Among those are the members of the cation:proton antiporter-2 (CPA2) family (or CHX family), predicted to encode Na(+),K(+)/H(+) antiporters. AtCHX17, a member of the CPA2 family, was selected for expression studies, and phenotypic analysis of knockout mutants was performed. AtCHX17 expression was only detected in roots. The gene was strongly induced by salt stress, potassium starvation, abscisic acid (ABA) and external acidic pH. Using the beta-glucuronidase reporter gene strategy and in situ RT-PCR experiments, we have found that AtCHX17 was expressed preferentially in epidermal and cortical cells of the mature root zones. Knockout mutants accumulated less K(+) in roots in response to salt stress and potassium starvation compared with the wild type. These data support the hypothesis that AtCHX17 is involved in K(+) acquisition and homeostasis.
authors.affiliation: Biochimie et Physiologie Moléculaire des Plantes, UMR 5004 INRA/CNRS/ENSA-M/UM II, place Viala 34060 Montpellier Cedex 1, France.
authors.forename: Françoise
authors.initials: F
authors.lastname: Cellier
authors.forename: Geneviève
authors.initials: G
authors.lastname: Conéjéro
authors.forename: Lilian
authors.initials: L
authors.lastname: Ricaud
authors.forename: Doan Trung
authors.initials: DT
authors.lastname: Luu
authors.forename: Marc
authors.initials: M
authors.lastname: Lepetit
authors.forename: Françoise
authors.initials: F
authors.lastname: Gosti
authors.forename: Francine
authors.initials: F
authors.lastname: Casse
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D001483:Base Sequence; D017124:Conserved Sequence; D017931:DNA Primers; D005966:Glucuronidase / Q000235:genetics; D006706:Homeostasis; D008969:Molecular Sequence Data; D030821:Plants, Genetically Modified / Q000378:metabolism; D011188:Potassium / Q000378:metabolism*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D017923:Sodium-Hydrogen Exchangers / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; C493886:CHX17 protein, Arabidopsis; D017931:DNA Primers; D017923:Sodium-Hydrogen Exchangers; D005966:Glucuronidase; D011188:Potassium