期刊
JOURNAL OF BIOLOGICAL CHEMISTRY
卷 286, 期 21, 页码 18474-18482出版社
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
DOI: 10.1074/jbc.M110.211953
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资金
- Interuniversity Poles of Attraction Program (Belgian State, Scientific, Technical and Cultural Services)
- Belgian National Fund for Scientific Research
- Fonds pour la formation a la Recherche dans l'Industrie et dans l'Agriculture (Belgium)
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, PMA2Thr-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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