Guard cell inward K+ channel activity in arabidopsis involves expression of the twin channel subunits KAT1 and KAT2.
Stomatal opening, which controls gas exchanges between plants and the atmosphere, results from an increase in turgor of the two guard cells that surround the pore of the stoma. KAT1 was the only inward K(+) channel shown to be expressed in Arabidopsis guard cells, where it was proposed to mediate a K(+) influx that enables stomatal opening. We report that another Arabidopsis K(+) channel, KAT2, is expressed in guard cells. More than KAT1, KAT2 displays functional features resembling those of native inward K(+) channels in guard cells. Coexpression in Xenopus oocytes and two-hybrid experiments indicated that KAT1 and KAT2 can form heteromultimeric channels. The data indicate that KAT2 plays a crucial role in the stomatal opening machinery.
Pilot
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G
Biochimie et Physiologie Moléculaire des Plantes, UMR 5004 Agro-M/CNRS/INRA/UM2, Place Viala, F-34060 Montpellier Cedex 1, France.
Lacombe
B
B
Gaymard
F
F
Cherel
I
I
Boucherez
J
J
Thibaud
J B
JB
Sentenac
H
H
D000595:Amino Acid Sequence; D000818:Animals; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins; D001483:Base Sequence; D003001:Cloning, Molecular; D018744:DNA, Plant / Q000032:analysis; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism; D010940:Plant Proteins; D015221:Potassium Channels / Q000096:biosynthesis* / Q000235:genetics* / Q000378:metabolism*; D024661:Potassium Channels, Inwardly Rectifying; D024642:Potassium Channels, Voltage-Gated; D012333:RNA, Messenger / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014162:Transfection; D014982:Xenopus laevis
D029681:Arabidopsis Proteins; D018744:DNA, Plant; C501210:KAT1 protein, Arabidopsis; C428126:KAT2 protein, Arabidopsis; D010940:Plant Proteins; D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; D024642:Potassium Channels, Voltage-Gated; D012333:RNA, Messenger