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Blue light activates the plasma membrane H + ‐ATPase by phosphorylation of the C‐terminus in stomatal guard cells
Author(s) -
Kinoshita Toshinori,
Shimazaki Kenichiro
Publication year - 1999
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/18.20.5548
Subject(s) - guard cell , phosphorylation , atpase , biology , threonine , protein kinase a , biochemistry , atp hydrolysis , serine , ion pump , microbiology and biotechnology , enzyme , chemistry , ion , organic chemistry
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 μmol/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.