A protein kinase, interacting with two calcineurin B-like proteins, regulates K+ transporter AKT1 in Arabidopsis.
Potassium is an essential mineral element for plant growth and development. Although it is known that plants absorb and transport K+ through membrane transporters, it remains unclear how these transporters are regulated. Here we show that the protein kinase CIPK23, encoded by the LKS1 gene, regulates K+ uptake under low-K+ conditions. Lesion of LKS1 significantly reduced K+ uptake and caused leaf chlorosis and growth inhibition, whereas overexpression of LKS1 significantly enhanced K+ uptake and tolerance to low K+. We demonstrate that CIPK23 directly phosphorylates the K+ transporter AKT1 and further find that CIPK23 is activated by the binding of two calcineurin B-like proteins, CBL1 and CBL9. We propose a model in which the CBL1/9-CIPK23 pathway ensures activation of AKT1 and enhanced K+ uptake under low-K+ conditions.
Xu
Jiang
J
State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, National Plant Gene Research Centre (Beijing), Beijing 100094, China.
Li
Hao-Dong
HD
Chen
Li-Qing
LQ
Wang
Yi
Y
Liu
Li-Li
LL
He
Liu
L
Wu
Wei-Hua
WH
D000818:Animals; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001693:Biological Transport, Active; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D018744:DNA, Plant / Q000235:genetics; D005260:Female; D017343:Genes, Plant; D066298:In Vitro Techniques; D017136:Ion Transport; D008954:Models, Biological; D016296:Mutagenesis; D009154:Mutation; D009865:Oocytes / Q000378:metabolism; D010641:Phenotype; D030821:Plants, Genetically Modified; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D014982:Xenopus laevis
D029681:Arabidopsis Proteins; C417306:CBL protein, Arabidopsis; D002135:Calcium-Binding Proteins; D018744:DNA, Plant; D015221:Potassium Channels; D011994:Recombinant Proteins; C074500:AKT1 protein, Arabidopsis; C514581:CIPK23 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases; D011188:Potassium