title: Two tonoplast MATE proteins function as turgor-regulating chloride channels inArabidopsis.
abstract: The central vacuole in a plant cell occupies the majority of the cellular volume and plays a key role in turgor regulation. The vacuolar membrane (tonoplast) contains a large number of transporters that mediate fluxes of solutes and water, thereby adjusting cell turgor in response to developmental and environmental signals. We report that two tonoplast Detoxification efflux carrier (DTX)/Multidrug and Toxic Compound Extrusion (MATE) transporters, DTX33 and DTX35, function as chloride channels essential for turgor regulation inArabidopsisEctopic expression of each transporter inNicotiana benthamianamesophyll cells elicited a large voltage-dependent inward chloride current across the tonoplast, showing that DTX33 and DTX35 each constitute a functional channel. Both channels are highly expressed inArabidopsistissues, including root hairs and guard cells that experience rapid turgor changes during root-hair elongation and stomatal movements. Disruption of these two genes, either in single or double mutants, resulted in shorter root hairs and smaller stomatal aperture, with double mutants showing more severe defects, suggesting that these two channels function additively to facilitate anion influx into the vacuole during cell expansion. In addition,dtx35single mutant showed lower fertility as a result of a defect in pollen-tube growth. Indeed, patch-clamp recording of isolated vacuoles indicated that the inward chloride channel activity across the tonoplast was impaired in the double mutant. Because MATE proteins are widely known transporters of organic compounds, finding MATE members as chloride channels expands the functional definition of this large family of transporters.
authors.affiliation: Institute of Plant Molecular Biology, State Key Laboratory of Pharmaceutical Technology, School of Life Sciences, Nanjing University, Nanjing 210093, China.|College of Life Sciences, Capital Normal University, Beijing 100048, China.|Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720.|Beijing Key Laboratory of Agricultural Genetic Resources and Biotechnology, Beijing Agro-Biotechnology Research Center, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China.
authors.forename: Haiwen
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Institute of Plant Molecular Biology, State Key Laboratory of Pharmaceutical Technology, School of Life Sciences, Nanjing University, Nanjing 210093, China; fgzhao@nju.edu.cn lgli@cnu.edu.cn sluan@berkeley.edu.
authors.forename: Fu-Geng
authors.initials: FG
authors.lastname: Zhao
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720.
authors.forename: Ren-Jie
authors.initials: RJ
authors.lastname: Tang
authors.affiliation: College of Life Sciences, Capital Normal University, Beijing 100048, China.
authors.forename: Yuexuan
authors.initials: Y
authors.lastname: Yu
authors.affiliation: College of Life Sciences, Capital Normal University, Beijing 100048, China.
authors.forename: Jiali
authors.initials: J
authors.lastname: Song
authors.affiliation: Institute of Plant Molecular Biology, State Key Laboratory of Pharmaceutical Technology, School of Life Sciences, Nanjing University, Nanjing 210093, China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Wang
authors.affiliation: College of Life Sciences, Capital Normal University, Beijing 100048, China; fgzhao@nju.edu.cn lgli@cnu.edu.cn sluan@berkeley.edu.
authors.forename: Legong
authors.initials: L
authors.lastname: Li
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720; fgzhao@nju.edu.cn lgli@cnu.edu.cn sluan@berkeley.edu.
authors.forename: Sheng
authors.initials: S
authors.lastname: Luan
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D018118:Chloride Channels / Q000235:genetics* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D007425:Intracellular Membranes / Q000378:metabolism* / Q000648:ultrastructure; D008564:Membrane Potentials / Q000502:physiology; D026901:Membrane Transport Proteins / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D009997:Osmotic Pressure; D018408:Patch-Clamp Techniques; D059828:Plant Cells / Q000378:metabolism / Q000648:ultrastructure; D018517:Plant Roots / Q000235:genetics* / Q000378:metabolism; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism; D014617:Vacuoles / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D029681:Arabidopsis Proteins; D018118:Chloride Channels; C000607559:DTX35 protein, Arabidopsis; D026901:Membrane Transport Proteins; D020033:Protein Isoforms
keywords: drought; root hair; stomata; vacuole