The Arabidopsis chaperone J3 regulates the plasma membrane H+-ATPase through interaction with the PKS5 kinase.

The plasma membrane H(+)-ATPase (PM H(+)-ATPase) plays an important role in the regulation of ion and metabolite transport and is involved in physiological processes that include cell growth, intracellular pH, and stomatal regulation. PM H(+)-ATPase activity is controlled by many factors, including hormones, calcium, light, and environmental stresses like increased ...
soil salinity. We have previously shown that the Arabidopsis thaliana Salt Overly Sensitive2-Like Protein Kinase5 (PKS5) negatively regulates the PM H(+)-ATPase. Here, we report that a chaperone, J3 (DnaJ homolog 3; heat shock protein 40-like), activates PM H(+)-ATPase activity by physically interacting with and repressing PKS5 kinase activity. Plants lacking J3 are hypersensitive to salt at high external pH and exhibit decreased PM H(+)-ATPase activity. J3 functions upstream of PKS5 as double mutants generated using j3-1 and several pks5 mutant alleles with altered kinase activity have levels of PM H(+)-ATPase activity and responses to salt at alkaline pH similar to their corresponding pks5 mutant. Taken together, our results demonstrate that regulation of PM H(+)-ATPase activity by J3 takes place via inactivation of the PKS5 kinase.
Mesh Terms:
Arabidopsis, Arabidopsis Proteins, Gene Expression Regulation, Plant, HSP40 Heat-Shock Proteins, Hydrogen-Ion Concentration, Microscopy, Confocal, Mutation, Plant Roots, Protein-Serine-Threonine Kinases, Proton-Translocating ATPases, RNA, Plant, Sodium Chloride
Plant Cell
Date: Apr. 01, 2010
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