Blue light activates the plasma membrane H(+)-ATPase by phosphorylation of the C-terminus in stomatal guard cells.
The opening of stomata, which is driven by the accumulation of K(+) salt in guard cells, is induced by blue light (BL). The BL activates the H(+) pump; however, the mechanism by which the perception of BL is transduced into the pump activation remains unknown. We present evidence that the pump is the plasma membrane H(+)-ATPase and that BL activates the H(+)-ATPase via phosphorylation. A pulse of BL (30 s, 100 micromol/m(2)/s) increased ATP hydrolysis by the plasma membrane H(+)-ATPase and H(+) pumping in Vicia guard cell protoplasts with a similar time course. The H(+)-ATPase was phosphorylated reversibly by BL, and the phosphorylation levels paralleled the ATP hydrolytic activity. The phosphorylation occurred exclusively in the C-termini of H(+)-ATPases on both serine and threonine residues in two isoproteins of H(+)-ATPase in guard cells. An endogenous 14-3-3 protein was co-precipitated with H(+)-ATPase, and the recombinant 14-3-3 protein bound to the phosphorylated C-termini of H(+)-ATPases. These findings demonstrate that BL activates the plasma membrane H(+)-ATPase via phosphorylation of the C-terminus by a serine/threonine protein kinase, and that the 14-3-3 protein has a key role in the activation.
Kinoshita
T
T
Department of Biology, Graduate School of Sciences, Kyushu University, Ropponmatsu, Fukuoka 810-8560, Japan.
Shimazaki
K i
Ki
D048948:14-3-3 Proteins; D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D002462:Cell Membrane / Q000201:enzymology; D017931:DNA Primers / Q000235:genetics; D004789:Enzyme Activation / Q000528:radiation effects; D007887:Fabaceae / Q000201:enzymology* / Q000235:genetics / Q000528:radiation effects; D006868:Hydrolysis; D008027:Light; D008969:Molecular Sequence Data; D010766:Phosphorylation; D010946:Plants, Medicinal; D011506:Proteins / Q000302:isolation & purification / Q000378:metabolism; D017494:Proton Pumps / Q000378:metabolism / Q000528:radiation effects; D006180:Proton-Translocating ATPases / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects*; D017386:Sequence Homology, Amino Acid; D014446:Tyrosine 3-Monooxygenase
D048948:14-3-3 Proteins; D017931:DNA Primers; D011506:Proteins; D017494:Proton Pumps; D000255:Adenosine Triphosphate; D014446:Tyrosine 3-Monooxygenase; D006180:Proton-Translocating ATPases