CPK13, a Noncanonical Ca2+-Dependent Protein Kinase, Specifically Inhibits KAT2 and KAT1 Shaker K+ Channels and Reduces Stomatal Opening    . Issue 1 (18th July 2014)

• Record Type: Journal Article
• Authors: Ronzier, Elsa; Corratgé-Faillie, Claire; Sanchez, Frédéric; Prado, Karine; Brière, Christian; Leonhardt, Nathalie; Thibaud, Jean-Baptiste; Xiong, Tou Cheu
• Is Part Of: Plant physiology. Volume 166:Issue 1(2014)
• Page Start: 314
• Page End: 326
• Publication Date: 2014-07-18
• Subjects: Plant physiology -- Periodicals; Botany -- Periodicals; Periodicals; Electronic journals; 571.2
• DOI: 10.1104/pp.114.240226
• Languages: English
• ISSNs: 0032-0889

Abstract

Abstract : A Ca 2+ -dependent kinase is identified that phosphorylates and inhibits inward potassium channels expressed in guard cells, the overexpression of which results in a reduction of stomatal aperture. Abstract: Ca 2 + -dependent protein kinases (CPKs) form a large family of 34 genes in Arabidopsis ( Arabidopsis thaliana ). Based on their dependence on Ca 2+, CPKs can be sorted into three types: strictly Ca 2+ -dependent CPKs, Ca 2+ -stimulated CPKs (with a significant basal activity in the absence of Ca 2+ ), and essentially calcium-insensitive CPKs. Here, we report on the third type of CPK, CPK13, which is expressed in guard cells but whose role is still unknown. We confirm the expression of CPK13 in Arabidopsis guard cells, and we show that its overexpression inhibits light-induced stomatal opening. We combine several approaches to identify a guard cell-expressed target. We provide evidence that CPK13 (1) specifically phosphorylates peptide arrays featuring Arabidopsis K + Channel KAT2 and KAT1 polypeptides, (2) inhibits KAT2 and/or KAT1 when expressed in Xenopus laevis oocytes, and (3) closely interacts in plant cells with KAT2 channels (Förster resonance energy transfer-fluorescence lifetime imaging microscopy). We propose that CPK13 reduces stomatal aperture through its inhibition of the guard cell-expressed KAT2 and KAT1 channels.