title: The ATP binding cassette transporter AtMRP5 modulates anion and calcium channel activities in Arabidopsis guard cells.
abstract: Stomatal guard cells control CO(2) uptake and water loss between plants and the atmosphere. Stomatal closure in response to the drought stress hormone, abscisic acid (ABA), results from anion and K(+) release from guard cells. Previous studies have shown that cytosolic Ca(2+) elevation and ABA activate S-type anion channels in the plasma membrane of guard cells, leading to stomatal closure. However, membrane-bound regulators of abscisic acid signaling and guard cell anion channels remain unknown. Here we show that the ATP binding cassette (ABC) protein AtMRP5 is localized to the plasma membrane. Mutation in the AtMRP5 ABC protein impairs abscisic acid and cytosolic Ca(2+) activation of slow (S-type) anion channels in the plasma membrane of guard cells. Interestingly, atmrp5 insertion mutant guard cells also show impairment in abscisic acid activation of Ca(2+)-permeable channel currents in the plasma membrane of guard cells. These data provide evidence that the AtMRP5 ABC transporter is a central regulator of guard cell ion channel during abscisic acid and Ca(2+) signal transduction in guard cells.
authors.affiliation: Institut für Pflanzenbiologie, University Zurich, Zollikerstrasse 107, 8008 Zurich, Switzerland.
authors.forename: Su Jeoung
authors.initials: SJ
authors.lastname: Suh
authors.forename: Yong-Fei
authors.initials: YF
authors.lastname: Wang
authors.forename: Annie
authors.initials: A
authors.lastname: Frelet
authors.forename: Nathalie
authors.initials: N
authors.lastname: Leonhardt
authors.forename: Markus
authors.initials: M
authors.lastname: Klein
authors.forename: Cyrille
authors.initials: C
authors.lastname: Forestier
authors.forename: Bernd
authors.initials: B
authors.lastname: Mueller-Roeber
authors.forename: Myeon H
authors.initials: MH
authors.lastname: Cho
authors.forename: Enrico
authors.initials: E
authors.lastname: Martinoia
authors.forename: Julian I
authors.initials: JI
authors.lastname: Schroeder
mesh_terms: D000040:Abscisic Acid / Q000737:chemistry*; D000255:Adenosine Triphosphate / Q000737:chemistry*; D000838:Anions; D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism / Q000502:physiology*; D002462:Cell Membrane / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D005816:Genetic Complementation Test; D005905:Glyburide / Q000494:pharmacology; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000378:metabolism / Q000502:physiology*; D030821:Plants, Genetically Modified / Q000378:metabolism; D011188:Potassium / Q000737:chemistry; D011485:Protein Binding; D011523:Protoplasts / Q000378:metabolism; D015398:Signal Transduction; D054047:Surgical Stomas
chemical_list: D000040:Abscisic Acid; D000255:Adenosine Triphosphate; D000838:Anions; D029681:Arabidopsis Proteins; D005905:Glyburide; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D011188:Potassium; C492374:ATMRP5 protein, Arabidopsis