5aar | pdb_00005aar
Structure of the ankyrin domain of an Arabidopsis Thaliana potassium channel
Structural highlights
FunctionAKT1_ARATH Highly selective inward-rectifying potassium channel that mediate potassium uptake by plant roots in response to low K(+) conditions, by a calcium-, CBL-, and CIPK-dependent pathway. Positively regulated by phosphorylation by CIPK23. Negatively regulated by a kinase-independent regulatory mechanism involving a competing direct binding of CBL10. Involved in the stomatal regulation by monitoring the turgor pressure in guard cells. Assuming opened or closed conformations in response to the voltage difference across the membrane, the channel is activated by hyperpolarization. May interact with the cytoskeleton or with regulatory proteins.[1] [2] [3] [4] [5] Publication Abstract from PubMedPlant growth largely depends on the maintenance of adequate intracellular levels of potassium (K(+)). The families of 10 Calcineurin B-Like (CBL) calcium sensors and 26 CBL-Interacting Protein Kinases (CIPKs) of Arabidopsis (Arabidopsis thaliana) decode the calcium signals elicited by environmental inputs to regulate different ion channels and transporters involved in the control of K(+) fluxes by phosphorylation-dependent and -independent events. However, the detailed molecular mechanisms governing target specificity require investigation. Here, we show that the physical interaction between CIPK23 and the noncanonical ankyrin domain in the cytosolic side of the inward-rectifier K(+) channel AKT1 regulates kinase docking and channel activation. Point mutations on this domain specifically alter binding to CIPK23, enhancing or impairing the ability of CIPK23 to regulate channel activity. Our data demonstrate the relevance of this protein-protein interaction that contributes to the formation of a complex between CIPK23/CBL1 and AKT1 in the membrane for the proper regulation of K(+) transport. Recognition and Activation of the Plant AKT1 Potassium Channel by the Kinase CIPK23.,Sanchez-Barrena MJ, Chaves-Sanjuan A, Raddatz N, Mendoza I, Cortes A, Gago F, Gonzalez-Rubio JM, Benavente JL, Quintero FJ, Pardo JM, Albert A Plant Physiol. 2020 Apr;182(4):2143-2153. doi: 10.1104/pp.19.01084. Epub 2020 Feb, 3. PMID:32015077[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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