title: The Transmembrane Region of Guard Cell SLAC1 Channels Perceives CO2 Signals via an ABA-Independent Pathway in Arabidopsis.
abstract: The guard cell S-type anion channel, SLOW ANION CHANNEL1 (SLAC1), a key component in the control of stomatal movements, is activated in response to CO2 and abscisic acid (ABA). Several amino acids existing in the N-terminal region of SLAC1 are involved in regulating its activity via phosphorylation in the ABA response. However, little is known about sites involved in CO2 signal perception. To dissect sites that are necessary for the stomatal CO2 response, we performed slac1 complementation experiments using transgenic plants expressing truncated SLAC1 proteins. Measurements of gas exchange and stomatal apertures in the truncated transgenic lines in response to CO2 and ABA revealed that sites involved in the stomatal CO2 response exist in the transmembrane region and do not require the SLAC1 N and C termini. CO2 and ABA regulation of S-type anion channel activity in guard cells of the transgenic lines confirmed these results. In vivo site-directed mutagenesis experiments targeted to amino acids within the transmembrane region of SLAC1 raise the possibility that two tyrosine residues exposed on the membrane are involved in the stomatal CO2 response.
authors.affiliation: Department of Biology, Faculty of Science, Kyushu University, Motooka, Nishi-ku, Fukuoka 819-0395, Japan.
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Yamamoto
authors.affiliation: Department of Biology, Faculty of Science, Kyushu University, Motooka, Nishi-ku, Fukuoka 819-0395, Japan.
authors.forename: Juntaro
authors.initials: J
authors.lastname: Negi
authors.affiliation: Cell and Developmental Biology Section, Division of Biological Sciences, University of California at San Diego, La Jolla, California 92093.
authors.forename: Cun
authors.identifier: http://orcid.org/0000-0001-6975-0959
authors.initials: C
authors.lastname: Wang
authors.affiliation: Department of Biotechnology, Faculty of Engineering, Biotechnology Research Center, Toyama Prefectural University, Imizu, Toyama 939-0398, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Isogai
authors.affiliation: Cell and Developmental Biology Section, Division of Biological Sciences, University of California at San Diego, La Jolla, California 92093.
authors.forename: Julian I
authors.initials: JI
authors.lastname: Schroeder
authors.affiliation: Department of Biology, Faculty of Science, Kyushu University, Motooka, Nishi-ku, Fukuoka 819-0395, Japan iba.koh.727@m.kyushu-u.ac.jp.
authors.forename: Koh
authors.initials: K
authors.lastname: Iba
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D019943:Amino Acid Substitution; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics* / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002245:Carbon Dioxide / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D010766:Phosphorylation; D054046:Plant Stomata / Q000378:metabolism; D030821:Plants, Genetically Modified; D015398:Signal Transduction
chemical_list: D029681:Arabidopsis Proteins; D008565:Membrane Proteins; C528438:SLAC1 protein, Arabidopsis; D002245:Carbon Dioxide; D000040:Abscisic Acid