ATP 是生物体重要的高能化合物，参与了细胞新陈代谢和生物体生长发育的几乎所有过程； ATP还是重要的胞外信号分子。细胞中绝大部分ATP是由ATP合酶(F1Fo-ATP synthase)合成。ATP合酶由多亚基组成，其中仅beta亚基具有催化活性。线粒体和叶绿体ATP合酶的beta亚基均有磷酸化修饰，但负责其磷酸化的激酶及磷酸化对其功能调控的研究很缺乏。项目组前期在拟南芥中的研究结果发现，MKK9-MPK3/MPK6参与的MAPK级联系统调控了叶绿体ATP合酶beta亚基（ATPB）的磷酸化和ATP的合成。本项目拟研究：（1）MKK9-MPK3/MPK6的上游MKKKx，构建一条参与ATPB磷酸化调控的完整MAPK三激酶级联系统；（2）该级联系统对ATPB磷酸化和磷酸化对叶绿体ATP合酶的调控。揭示磷酸化叶绿体ATPB的激酶及磷酸化对ATP合酶功能调控的机理。

Adenosine 5’-triphosphate (ATP), the universal metabolic energy carrier that links catabolic and anabolic pathways, is involved in the regulation of the most biological processes during growth, development and response to environment in all organisms. ATP also acts as an extracellular signaling molecule. The majority of ATP in cells is synthesized by the enzymes of F1Fo-ATP synthase. ATP synthase is a protein complex with multiple subunits. The beta subunit of ATP synthase is responsible for catalyzing the synthesis of ATP. Several reports have revealed that the beta subunit of the mitochondrial and chloroplast ATP synthases can be phosphorylated. However, the kinase that involves in the phosphorylation of its beta subunit and the function of the beta subunit phosphorylation are currently unknown. Our preliminary data show that, MKK9-MPK3/MPK6 mediated MAPK cascade is involved in the phosphorylation of the beta subunit of chloroplast ATP synthase (namely as ATPB), and subsequently regulates ATP synthesis in Arabidopsis. In this project, we proposed to identify and analyze the upstream MKKKx of MKK9-MPK3/MPK6 during the phosphorylation of ATPB, and study the regulation of ATPB phosphorylation on function of chloroplast ATP synthase. The results obtained from this project will facilitate us to explore the kinase that phosphorylates ATPB and understand the mechanism of chloroplast ATP synthase regulation by ATPB phosphorylation.