title: Modulation of plant TPC channels by polyunsaturated fatty acids.
abstract: Polyunsaturated fatty acids (PUFAs) are powerful modulators of several animal ion channels. It is shown here that PUFAs strongly affect the activity of the Slow Vacuolar (SV) channel encoded by the plant TPC1 gene. The patch-clamp technique was applied to isolated vacuoles from carrot taproots and Arabidopsis thaliana mesophyll cells and arachidonic acid (AA) was chosen as a model molecule for PUFAs. Our study was extended to different PUFAs including the endogenous alpha-linolenic acid (ALA). The addition of micromolar concentrations of AA reversibly inhibited the SV channel decreasing the maximum open probability and shifting the half activation voltage to positive values. Comparing the effects of different PUFAs, it was found that the length of the lipophilic acyl chain, the number of double bonds and the polar head were critical for channel modulation.The experimental data can be reproduced by a simple three-state model, in which PUFAs do not interact directly with the voltage sensors but affect the voltage-independent transition that leads the channel from the open state to the closed configuration. The results indicate that lipids play an important role in co-ordinating ion channel activities similar to what is known from animal cells.
authors.affiliation: Istituto di Biofisica, Consiglio Nazionale delle Ricerche, Via De Marini 6, 16149 Genova,  Italy.
authors.forename: Paul Vijay Kanth
authors.initials: PV
authors.lastname: Gutla
authors.forename: Anna
authors.initials: A
authors.lastname: Boccaccio
authors.forename: Alexis
authors.initials: A
authors.lastname: De Angeli
authors.forename: Franco
authors.initials: F
authors.lastname: Gambale
authors.forename: Armando
authors.initials: A
authors.lastname: Carpaneto
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000378:metabolism; D016718:Arachidonic Acid / Q000737:chemistry / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000378:metabolism; D018552:Daucus carota / Q000187:drug effects / Q000502:physiology*; D004594:Electrophysiology; D005231:Fatty Acids, Unsaturated / Q000737:chemistry / Q000494:pharmacology*; D015640:Ion Channel Gating; D007473:Ion Channels / Q000378:metabolism*; D007700:Kinetics; D019787:Linoleic Acid / Q000378:metabolism; D008564:Membrane Potentials; D058503:Mesophyll Cells / Q000502:physiology; D008954:Models, Biological; D009829:Oleic Acids / Q000378:metabolism; D018408:Patch-Clamp Techniques; D010940:Plant Proteins / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000502:physiology; D014617:Vacuoles / Q000378:metabolism*; D017962:alpha-Linolenic Acid / Q000378:metabolism; D000097903:Two-Pore Channels
chemical_list: D029681:Arabidopsis Proteins; D016718:Arachidonic Acid; D002118:Calcium; D015220:Calcium Channels; D005231:Fatty Acids, Unsaturated; D007473:Ion Channels; D019787:Linoleic Acid; D009829:Oleic Acids; D010940:Plant Proteins; D017962:alpha-Linolenic Acid; C498240:TPC1 protein, Arabidopsis; D000097903:Two-Pore Channels