title: Plant K(in) and K(out) channels: approaching the trait of opposite rectification by analyzing more than 250 KAT1-SKOR chimeras.
abstract: Members of the Shaker-like plant K(+) channel family share a common structure, but are highly diverse in their function: they behave as either hyperpolarization-activated inward-rectifying (K(in)) channels, or leak-like (K(weak)) channels, or depolarization-activated outward-rectifying (K(out)) channels. Here we created 256 chimeras between the K(in) channel KAT1 and the K(out) channel SKOR. The chimeras were screened in a potassium-uptake deficient yeast strain to identify those, which mediate potassium inward currents, i.e., which are functionally equivalent to KAT1. This strategy allowed us to identify three chimeras which differ from KAT1 in three parts of the polypeptide: the cytosolic N-terminus, the cytosolic C-terminus, and the putative voltage-sensor S4. Additionally, mutations in the K(out) channel SKOR were generated in order to localize molecular entities underlying its depolarization activation. The triple mutant SKOR-D312N-M313L-I314G, carrying amino-acid changes in the S6 segment, was identified as a channel which did not display any rectification in the tested voltage-range.
authors.affiliation: Biochimie et Physiologie Moléculaires des Plantes, UMR 5004, Agro.M-CNRS-INRA-UM2, Montpellier, France.
authors.forename: Fabien
authors.initials: F
authors.lastname: Porée
authors.forename: Klaas
authors.initials: K
authors.lastname: Wulfetange
authors.forename: Alessia
authors.initials: A
authors.lastname: Naso
authors.forename: Armando
authors.initials: A
authors.lastname: Carpaneto
authors.forename: Anja
authors.initials: A
authors.lastname: Roller
authors.forename: Gabriel
authors.initials: G
authors.lastname: Natura
authors.forename: Adam
authors.initials: A
authors.lastname: Bertl
authors.forename: Hervé
authors.initials: H
authors.lastname: Sentenac
authors.forename: Jean-Baptiste
authors.initials: JB
authors.lastname: Thibaud
authors.forename: Ingo
authors.initials: I
authors.lastname: Dreyer
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015640:Ion Channel Gating / Q000502:physiology*; D008564:Membrane Potentials / Q000502:physiology; D008969:Molecular Sequence Data; D011188:Potassium / Q000378:metabolism*; D015221:Potassium Channels / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D024661:Potassium Channels, Inwardly Rectifying / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D051637:Shaker Superfamily of Potassium Channels; D013329:Structure-Activity Relationship
chemical_list: D029681:Arabidopsis Proteins; C501210:KAT1 protein, Arabidopsis; D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; D020033:Protein Isoforms; D011994:Recombinant Proteins; C114544:SKOR protein, Arabidopsis; D051637:Shaker Superfamily of Potassium Channels; D011188:Potassium