title: Functional identification of a GORK potassium channel from the ancient desert shrub Ammopiptanthus mongolicus (Maxim.) Cheng f.
abstract: A GORK homologue K(+) channel from the ancient desert shrub Ammopiptanthus mongolicus (Maxim.) Cheng f. shows the functional conservation of the GORK channels among plant species. Guard cell K(+) release through the outward potassium channels eventually enables the closure of stomata which consequently prevents plant water loss from severe transpiration. Early patch-clamp studies with the guard cells have revealed many details of such outward potassium currents. However, genes coding for these potassium-release channels have not been sufficiently characterized from species other than the model plant Arabidopsis thaliana. We report here the functional identification of a GORK (for Gated or Guard cell Outward Rectifying K(+) channels) homologue from the ancient desert shrub Ammopiptanthus mongolicus (Maxim.) Cheng f. AmGORK was primary expressed in shoots, where the transcripts were regulated by stress factors simulated by PEG, NaCl or ABA treatments. Patch-clamp measurements on isolated guard cell protoplasts revealed typical depolarization voltage gated outward K(+) currents sensitive to the extracelluar K(+) concentration and pH, resembling the fundamental properties previously described in other species. Two-electrode voltage-clamp analysis in Xenopus lavies oocytes with AmGORK reconstituted highly similar characteristics as assessed in the guard cells, supporting that the function of AmGORK is consistent with a crucial role in mediating stomatal closure in Ammopiptanthus mongolicus. Furthermore, a single amino acid mutation D297N of AmGORK eventually abolishes both the voltage-gating and its outward rectification and converts the channel into a leak-like channel, indicating strong involvement of this residue in the gating and voltage dependence of AmGORK. Our results obtained from this anciently originated plant support a strong functional conservation of the GORK channels among plant species and maybe also along the progress of revolution.
authors.affiliation: College of Forestry, Nanjing Forestry University, Nanjing, 210037, China.|Co-Innovation Center for the Sustainable Forestry in Southern China, Nanjing Forest University, Nanjing, 210037, China.|State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China.
authors.forename: Junlin
authors.initials: J
authors.lastname: Li
authors.affiliation: College of Forestry, Nanjing Forestry University, Nanjing, 210037, China.|Co-Innovation Center for the Sustainable Forestry in Southern China, Nanjing Forest University, Nanjing, 210037, China.
authors.forename: Huanchao
authors.initials: H
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China.
authors.forename: Han
authors.initials: H
authors.lastname: Lei
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China.
authors.forename: Man
authors.initials: M
authors.lastname: Jin
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China.
authors.forename: Guangzhen
authors.initials: G
authors.lastname: Yue
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China. yhsu@issas.ac.cn.
authors.forename: Yanhua
authors.initials: Y
authors.lastname: Su
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001464:Barium / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D003001:Cloning, Molecular; D003889:Desert Climate; D007887:Fabaceae / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D015640:Ion Channel Gating; D009154:Mutation / Q000235:genetics; D009865:Oocytes / Q000378:metabolism; D018408:Patch-Clamp Techniques; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011523:Protoplasts / Q000166:cytology / Q000378:metabolism; D017422:Sequence Analysis, DNA; D019789:Tetraethylammonium / Q000494:pharmacology; D014981:Xenopus
chemical_list: D010940:Plant Proteins; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D001464:Barium; D019789:Tetraethylammonium; D002118:Calcium
keywords: Ammopiptanthus mongolicus; Functional characterization; GORK; Patch-clamp; Two-electrode voltage-clamp