A Phosphorylation in the C-terminal Auto-inhibitory Domain of the Plant Plasma Membrane H+-ATPase Activates the Enzyme with No Requirement for Regulatory 14-3-3 Proteins.

Piette, Anne-Sophie;Derua, Rita;Waelkens, Etienne;Boutry, Marc;Duby, Geoffrey
(2011) Journal of Biological Chemistry — Vol. 286, n° 21, p. 18474-18482 (2011)

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Authors
  • Piette, Anne-SophieUCLouvain
    Author
  • Derua, Rita
    Author
  • Waelkens, Etienne
    Author
  • Boutry, MarcUCLouvain
    Author
  • Duby, GeoffreyUCLouvain
    Author
Abstract
The plant plasma membrane H(+)-ATPase is regulated by an auto-inhibitory C-terminal domain that can be displaced by phosphorylation of the penultimate residue, a Thr, and the subsequent binding of 14-3-3 proteins. By mass spectrometric analysis of plasma membrane H(+)-ATPase isoform 2 (PMA2) isolated from Nicotiana tabacum plants and suspension cells, we identified a new phosphorylation site, Thr-889, in a region of the C-terminal domain upstream of the 14-3-3 protein binding site. This residue was mutated into aspartate or alanine, and the mutated H(+)-ATPases expressed in the yeast Saccharomyces cerevisiae. Unlike wild-type PMA2, which could replace the yeast H(+)-ATPases, the PMA2-Thr889Ala mutant did not allow yeast growth, whereas the PMA2-Thr889Asp mutant resulted in improved growth and increased H(+)-ATPase activity despite reduced phosphorylation of the PMA2 penultimate residue and reduced 14-3-3 protein binding. To determine whether the regulation taking place at Thr-889 was independent of phosphorylation of the penultimate residue and 14-3-3 protein binding, we examined the effect of combining the PMA2-Thr889Asp mutation with mutations of other residues that impair phosphorylation of the penultimate residue and/or binding of 14-3-3 proteins. The results showed that in yeast, PMA2 Thr-889 phosphorylation could activate H(+)-ATPase if PMA2 was also phosphorylated at its penultimate residue. However, binding of 14-3-3 proteins was not required, although 14-3-3 binding resulted in further activation. These results were confirmed in N. tabacum suspension cells. These data define a new H(+)-ATPase activation mechanism that can take place without 14-3-3 proteins.
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Piette, A.-S., Derua, R., Waelkens, E., Boutry, M., & Duby, G. (2011). A Phosphorylation in the C-terminal Auto-inhibitory Domain of the Plant Plasma Membrane H+-ATPase Activates the Enzyme with No Requirement for Regulatory 14-3-3 Proteins. Journal of Biological Chemistry, 286(21), 18474-18482. https://doi.org/10.1074/jbc.M110.211953 (Original work published 2011)