title: AtKC1 is a general modulator of Arabidopsis inward Shaker channel activity.
abstract: A functional Shaker potassium channel requires assembly of four α-subunits encoded by a single gene or various genes from the Shaker family. In Arabidopsis thaliana, AtKC1, a Shaker α-subunit that is silent when expressed alone, has been shown to regulate the activity of AKT1 by forming heteromeric AtKC1-AKT1 channels. Here, we investigated whether AtKC1 is a general regulator of channel activity. Co-expression in Xenopus oocytes of a dominant negative (pore-mutated) AtKC1 subunit with the inward Shaker channel subunits KAT1, KAT2 or AKT2, or the outward subunits SKOR or GORK, revealed that the three inward subunits functionally interact with AtKC1 while the outward ones cannot. Localization experiments in plant protoplasts showed that KAT2 was able to re-locate AtKC1 fused to GFP from endomembranes to the plasma membrane, indicating that heteromeric AtKC1-KAT2 channels are efficiently targeted to the plasma membrane. Functional properties of heteromeric channels involving AtKC1 and KAT1, KAT2 or AKT2 were analysed by voltage clamp after co-expression of the respective subunits in Xenopus oocytes. AtKC1 behaved as a regulatory subunit within the heterotetrameric channel, reducing the macroscopic conductance and negatively shifting the channel activation potential. Expression studies showed that AtKC1 and its identified Shaker partners have overlapping expression patterns, supporting the hypothesis of a general regulation of inward channel activity by AtKC1 in planta. Lastly, AtKC1 disruption appeared to reduce plant biomass production, showing that AtKC1-mediated channel activity regulation is required for normal plant growth.
authors.affiliation: Biochimie et Physiologie Moléculaire des Plantes, UMR CNRS (5004)/INRA (388)/SupAgro/UM2, Campus INRA/Montpellier SupAgro, 2 Place Viala, 34060 Montpellier Cedex 2, France.
authors.forename: Linda
authors.initials: L
authors.lastname: Jeanguenin
authors.forename: Carine
authors.initials: C
authors.lastname: Alcon
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Duby
authors.forename: Martin
authors.initials: M
authors.lastname: Boeglin
authors.forename: Isabelle
authors.initials: I
authors.lastname: Chérel
authors.forename: Isabelle
authors.initials: I
authors.lastname: Gaillard
authors.forename: Sabine
authors.initials: S
authors.lastname: Zimmermann
authors.forename: Hervé
authors.initials: H
authors.lastname: Sentenac
authors.forename: Anne-Aliénor
authors.initials: AA
authors.lastname: Véry
mesh_terms: D000818:Animals; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D018533:Biomass; D002462:Cell Membrane / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D059828:Plant Cells / Q000378:metabolism / Q000648:ultrastructure; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels / Q000235:genetics / Q000378:metabolism; D024661:Potassium Channels, Inwardly Rectifying / Q000235:genetics / Q000378:metabolism; D024642:Potassium Channels, Voltage-Gated / Q000235:genetics / Q000378:metabolism; D060066:Protein Interaction Maps; D055503:Protein Multimerization; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins; D017384:Sequence Deletion; D051637:Shaker Superfamily of Potassium Channels / Q000235:genetics / Q000378:metabolism*; D014981:Xenopus / Q000235:genetics / Q000378:metabolism
chemical_list: C097485:AKT2 protein, Arabidopsis; D029681:Arabidopsis Proteins; C501210:KAT1 protein, Arabidopsis; C428126:KAT2 protein, Arabidopsis; C501895:LKT1 protein, Arabidopsis; D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; D024642:Potassium Channels, Voltage-Gated; D021122:Protein Subunits; D011993:Recombinant Fusion Proteins; D051637:Shaker Superfamily of Potassium Channels; D011188:Potassium