The Arabidopsis Chaperone J3 Regulates the Plasma Membrane H^sup +^-ATPase through Interaction with the PKS5 Kinase(C)(W)

• Published in: The Plant cell Vol. 22; no. 4; p. 1313
• Main Authors: Yang, Yongqing, Qin, Yunxia, Xie, Changgen, Zhao, Feiyi, Zhao, Jinfeng, Liu, Dafa, Chen, Shouyi, Fuglsang, Anja T, Palmgren, Michael G, Schumaker, Karen S, Deng, Xing Wang, Guo, Yan
• Format: Journal Article
• Language: English
• Published: Rockville American Society of Plant Biologists 01.04.2010
• Subjects: Environmental stress; Hormones; Inactivation; Metabolites; Salts; Soil salinity
• ISSN: 1040-4651; 1532-298X

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.