细胞质动力蛋白在细胞膜上锚定的结构基础和调节机制

Cytoplasmic dynein is a large microtubule-based molecular motor that is responsible for the intracellular transport of various cargoes, including proteins, organelles, RNAs and viruses. It has been recently shown that, while associated with the microtubule, dynein also needs to be anchored to some fixed structure in the cell in order to generate pulling forces for transporting cargoes through walking on microtubules. For example, dynein must be anchored to the cell membrane to position the spindle during mitosis, and it is anchored to some organelles to generate pulling forces for centrosome centration in the early embryos of multicellular animals. However, it is poorly known how dynein is anchored to these structures. In this proposal, we will investigate the structural basis and mechanism of regulation for dynein anchoring at the cell membrane, by using the spindle positioning during the asymmetric cell division of budding yeast as a model. Num1 is the receptor protein of dynein at the cell membrane. The N-terminal PA (Patch Assembly) domain of Num1 is necessary and sufficient to anchor dynein at the cell membrane. We plan to solve the structure of PA domain, isolate the protein(s) that binds to the PA domain and carry out functional analysis of the protein(s). Results from this study will provide insights into the molecular mechanism of associated diseases in humans.

细胞质动力蛋白是一个大的在微管上运动的分子马达，负责细胞内各种物质的转运，包括各种蛋白、细胞器、RNAs和病毒等。最近研究表明，为了通过在微管上运动产生拉力转运货物，动力蛋白在与微管相连的同时，还需要被锚定(anchor)于细胞内某个固定结构上。例如，为了完成有丝分裂过程中的纺锤体定位，动力蛋白需要被锚定于细胞膜上；而在多细胞动物的胚胎发育早期，动力蛋白被锚定于某些细胞器上，以产生拉力向细胞中心转移中心体。 但是，动力蛋白如何被锚定于这些结构上目前还不是很清楚。本项目拟以芽殖酵母的非对称性细胞分裂过程中的纺锤体定位为模式，研究动力蛋白在细胞膜上锚定的结构基础和调节机制。Num1是动力蛋白在细胞膜上的受体蛋白，其N末端的PA结构域对于动力蛋白的细胞膜锚定是必需而且足够的，我们将解析PA结构域的结构、分离与它相结合的蛋白并解析其功能。研究结果将为洞悉相关人类疾病的分子机理提供线索。