Plant K(in) and K(out) channels: approaching the trait of opposite rectification by analyzing more than 250 KAT1-SKOR chimeras.
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.
Porée
Fabien
F
Biochimie et Physiologie Moléculaires des Plantes, UMR 5004, Agro.M-CNRS-INRA-UM2, Montpellier, France.
Wulfetange
Klaas
K
Naso
Alessia
A
Carpaneto
Armando
A
Roller
Anja
A
Natura
Gabriel
G
Bertl
Adam
A
Sentenac
Hervé
H
Thibaud
Jean-Baptiste
JB
Dreyer
Ingo
I
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
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