TY  - JOUR
A1  - Held, Katrin
A1  - Pascaud, Francois
A1  - Eckert, Christian
A1  - Gajdanowicz, Pawel
A1  - Hashimoto, Kenji
A1  - Corratge-Faillie, Claire
A1  - Offenborn, Jan Niklas
A1  - Lacombe, Benoit
A1  - Dreyer, Ingo
A1  - Thibaud, Jean-Baptiste
A1  - Kudla, Jörg
T1  - Calcium-dependent modulation and plasma membrane targeting of the AKT2 potassium channel by the CBL4/CIPK6 calcium sensor/protein kinase complex
JF  - Cell research
N2  - Potassium (K(+)) channel function is fundamental to many physiological processes. However, components and mechanisms regulating the activity of plant K(+) channels remain poorly understood. Here, we show that the calcium (Ca(2+)) sensor CBL4 together with the interacting protein kinase CIPK6 modulates the activity and plasma membrane (PM) targeting of the K(+) channel AKT2 from Arabidopsis thaliana by mediating translocation of AKT2 to the PM in plant cells and enhancing AKT2 activity in oocytes. Accordingly, akt2, cbl4 and cipk6 mutants share similar developmental and delayed flowering phenotypes. Moreover, the isolated regulatory C-terminal domain of CIPK6 is sufficient for mediating CBL4- and Ca(2+)-dependent channel translocation from the endoplasmic reticulum membrane to the PM by a novel targeting pathway that is dependent on dual lipid modifications of CBL4 by myristoylation and palmitoylation. Thus, we describe a critical mechanism of ion-channel regulation where a Ca(2+) sensor modulates K(+) channel activity by promoting a kinase interaction-dependent but phosphorylation-independent translocation of the channel to the PM.
KW  - calcium sensor
KW  - protein kinase
KW  - potassium channel
KW  - signal transduction
Y1  - 2011
U6  - https://doi.org/10.1038/cr.2011.50
SN  - 1001-0602
VL  - 21
IS  - 7
SP  - 1116
EP  - 1130
PB  - Nature Publ. Group
CY  - Shanghai
ER  - 
TY  - JOUR
A1  - Gajdanowicz, Pawel
A1  - Michard, Erwan
A1  - Sandmann, Michael
A1  - Rocha, Marcio
A1  - Correa, Luiz Gustavo Guedes
A1  - Ramirez-Aguilar, Santiago J.
A1  - Gomez-Porras, Judith L.
A1  - Gonzalez, Wendy
A1  - Thibaud, Jean-Baptiste
A1  - van Dongen, Joost T.
A1  - Dreyer, Ingo
T1  - Potassium (K plus ) gradients serve as a mobile energy source in plant vascular tissues
JF  - Proceedings of the National Academy of Sciences of the United States of America
N2  - The essential mineral nutrient potassium (K(+)) is the most important inorganic cation for plants and is recognized as a limiting factor for crop yield and quality. Nonetheless, it is only partially understood how K(+) contributes to plant productivity. K(+) is used as a major active solute to maintain turgor and to drive irreversible and reversible changes in cell volume. K(+) also plays an important role in numerous metabolic processes, for example, by serving as an essential cofactor of enzymes. Here, we provide evidence for an additional, previously unrecognized role of K(+) in plant growth. By combining diverse experimental approaches with computational cell simulation, we show that K(+) circulating in the phloem serves as a decentralized energy storage that can be used to overcome local energy limitations. Posttranslational modification of the phloem-expressed Arabidopsis K(+) channel AKT2 taps this "potassium battery," which then efficiently assists the plasma membrane H(+)-ATPase in energizing the transmembrane phloem (re) loading processes.
KW  - channel gating
KW  - energy limiting condition
KW  - phloem reloading
KW  - posttranslational regulation
KW  - potassium channel
Y1  - 2011
U6  - https://doi.org/10.1073/pnas.1009777108
SN  - 0027-8424
VL  - 108
IS  - 2
SP  - 864
EP  - 869
PB  - National Acad. of Sciences
CY  - Washington
ER  -