Klimecka Maria, Szczegielniak Jadwiga, Godecka Luiza, Lewandowska-Gnatowska Elżbieta, Dobrowolska Grażyna, Muszyńska Grażyna
Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warszawa, Poland.
Acta Biochim Pol. 2011;58(4):589-95. Epub 2011 Dec 12.
In plant cells, phospholipids are not only membrane components but also act as second messengers interacting with various proteins and regulating diverse cellular processes, including stress signal transduction. Here, we report studies on the effects of various phospholipids on the activity and expression of maize wound-responsive calcium-dependent protein kinase (ZmCPK11). Our results revealed that in leaves treated with n-butanol, a potent inhibitor of phosphatidic acid (PA) synthesis catalyzed by phospholipase D, a significant decrease of ZmCPK11 activity was observed, indicating contribution of PA in the kinase activation. Using lipid binding assays, we demonstrate that among various phospholipids only saturated acyl species (16:0 and 18:0) of phosphatidic acid are able to bind to ZmCPK11. Saturated acyl species of PA are also able to stimulate phosphorylation of exogenous substrates by ZmCPK11 and autophosphorylation of the kinase. The level of ZmCPK11 autophosphorylation is correlated with its enzymatic activity. RT-PCR analysis showed that transcript level of ZmCPK11 in maize leaves increased in response to PA treatment. The influence of PA on the activity and transcript level of ZmCPK11 suggests an involvement of this kinase in a PA-mediated wound signal transduction pathway.
在植物细胞中，磷脂不仅是膜的组成成分，还作为第二信使与多种蛋白质相互作用，调节包括应激信号转导在内的各种细胞过程。在此，我们报告了关于各种磷脂对玉米创伤响应钙依赖性蛋白激酶（ZmCPK11）活性和表达影响的研究。我们的结果显示，在用磷脂酶D催化的磷脂酸（PA）合成的有效抑制剂正丁醇处理的叶片中，观察到ZmCPK11活性显著降低，表明PA在激酶激活中起作用。通过脂质结合试验，我们证明在各种磷脂中，只有磷脂酸的饱和酰基种类（16:0和18:0）能够与ZmCPK11结合。PA的饱和酰基种类也能够刺激ZmCPK11对外源底物的磷酸化以及该激酶的自身磷酸化。ZmCPK11自身磷酸化的水平与其酶活性相关。RT-PCR分析表明，玉米叶片中ZmCPK11的转录水平响应PA处理而增加。PA对ZmCPK11活性和转录水平的影响表明该激酶参与了PA介导的创伤信号转导途径。
