STRUCTURAL STUDIES OF NUCLEIC ACID MOTORS

我们正在使用X射线晶体学方法研究解旋酶的机制和组装，以深入了解DNA复制和核输出，这两种缺陷可能导致癌症的途径。特别是，通过对噬菌体T7的解旋酶/引发酶的结构研究，我将讨论DNA解旋的机制，以确定六聚体T7解旋酶/引发酶是否采用类似于F1-ATP酶的结合变化机制或类似于二聚体解旋酶的机制。我也期望通过T7解旋酶/引发酶和单链DNA结合蛋白之间的复合物的晶体结构测定来深入了解复制叉处的组装。我对mRNA输出因子RAT 8/Dbp 5的结构研究集中在伴随RAT 8/Dbp 5从细胞核到核孔，最后到细胞质的穿梭的蛋白质-蛋白质相互作用。这将通过单独的RAT 8/Dbp 5和与RAT 7/Nup 159（其在核孔处的相互作用伴侣）复合的RAT 8/Dbp 5的晶体结构测定来实现。

We are studying the mechanism and assembly of helicases using x-ray crystallographic methods in order to gain insight into DNA replication and nuclear export, two pathways in which defects can cause cancer. In particular, through structural investigations of the helicase/primase from bacteriophage T7, I will address the mechanism of DNA unwinding to determine whether the hexameric T7 helicase/primase adopts a mechanism similar to the binding-change mechanism of F1-ATPase or a mechanism similar to dimeric helicases. I also expect to gain insight into assembly at the replication fork through the crystal structure determination of a complex between the T7 helicase/primase and single- stranded DNA binding protein. My structural studies on the mRNA export factor RAT8/Dbp5 focus on the protein-protein interactions that accompany the shuttling of RAT8/Dbp5 from the nucleus to the nuclear pore and finally to the cytoplasm. This will be accomplished through crystal structure determination of RAT8/Dbp5 alone and in complex with RAT7/Nup159, its interaction partner at the nuclear pore.