An essential function of phosphatidylinositol phosphates in activation of plant shaker-type K+ channels.
A prominent regulatory property of plant shaker-type K+ channels is the 'rundown' that causes channel closure upon membrane excision from the cell, implicating intracellular factor(s) in maintaining channel activity. One such factor has been identified as hydrolysable ATP-Mg although the mechanism for ATP function remains unknown. Here we report identification of phosphatidylinositol (PI) phosphates (PIPs) as essential regulators for the voltage-dependent and -independent activation of plant shaker-type channels such as SKOR, an outward rectifying K+ channel. Inhibition of PI kinase activity abolished the function of ATP-Mg in restoration of rundown channel activity, demonstrating that PIPs production by PI kinases and ATP-Mg underlies ATP-induced activation of the rundown channel. We also identified aluminum block as a common feature of the plant shaker-type channels and provided evidence that aluminum block of these channels may result from Al interaction with PIPs.
Liu
Kun
K
Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA.
Li
Legong
L
Luan
Sheng
S
D000535:Aluminum / Q000494:pharmacology; D000818:Animals; D017360:Arabidopsis / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000502:physiology; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology*; D008564:Membrane Potentials / Q000502:physiology; D008969:Molecular Sequence Data; D009865:Oocytes; D030781:Organisms, Genetically Modified; D018129:Phosphatidylinositol Phosphates / Q000502:physiology*; D015221:Potassium Channels / Q000502:physiology*; D024661:Potassium Channels, Inwardly Rectifying / Q000502:physiology; D051637:Shaker Superfamily of Potassium Channels; D015398:Signal Transduction; D014982:Xenopus laevis
D029681:Arabidopsis Proteins; C501210:KAT1 protein, Arabidopsis; C501895:LKT1 protein, Arabidopsis; D018129:Phosphatidylinositol Phosphates; D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; C114544:SKOR protein, Arabidopsis; D051637:Shaker Superfamily of Potassium Channels; D000535:Aluminum