运用固体核磁技术研究磷脂双分子层中脂分子和DAGK的相互作用

The interactions between membrane proteins and the surrounded bilayer environment play important roles in the stability and function of such proteins. The secondary structure and the topology of Diacylglycerol kinase (DAGK) in the native lipid bilayer revealed by solid-state NMR，are different from those determined by solution-state NMR and X-ray crystallography. And it is also reported that the catalytic activity of DAGK was found to be markedly depended on the head group of lipids and the length of the fatty acyl chain in the lipid bilayer environment. These imply that the lipid molecules are contributing to maintaining the structure of DAGK and regulating its activity. However, it is still unclear that how lipid molecules modulate DAGK’s structure and activity. The project is going to investigate the interacting surface of lipids and DAGK in the native lipid bilayer environment by magic angle spinning solid state NMR (MAS ssNMR) technology and the different carbon 13 labeling strategy of lipid and DAGK, by which to elucidate the molecular mechanism of the interplay between lipids and DAGK. To further investigate the influence of the lipids to the structure and catalytic activity of DAGK, we will use computational techniques, and in particular MD simulations, to build up a complete model of lipids and DAGK in the lipid bilayer depending on the information of MAS ssNMR experiments and 3D structures. The research is going to elucidate the molecular mechanism of the interplay between lipids and DAGK in the native lipid bilayer, and also could make an explanation of lipids modulation to DAGK. The strategy and technology we are exploring are going to shed new light on the lipid-membrane protein research.

细胞膜的磷脂双分子层对维持膜蛋白的结构稳定性和功能有非常重要的作用。本课题组利用固体核磁共振技术得到的大肠杆菌的二酯酰甘油激酶（DAGK）在大肠杆菌磷脂双分子层中的二级结构和拓扑学结构，与液体NMR和X射线晶体学的结构比较有明显差异，这说明脂分子对膜蛋白的结构有影响。文献中亦有报道DAGK蛋白的催化活性受到脂分子头部基团种类和脂肪酸碳链长度的调控。虽然脂环境对DAGK的结构和功能有影响，但是它们相互作用的机理还不清楚。本项目拟用魔角旋转固体核磁共振（MAS ssNMR）技术,通过用不同方式标记DAGK蛋白和脂分子，可以获得天然环境中脂分子和DAGK相互作用界面的信息。基于以上信息，利用分子动力学方法建立脂分子和DAGK相互作用的模型，进一步说明脂分子调控DAGK蛋白功能的机理。本研究通过研究脂分子和DAGK的相互作用，探索在天然膜环境中脂分子对膜蛋白功能的影响。