CRYSTALLOGRAPHIC STUDIES OF DNA HELICASES

Rep DNA解旋酶是一种DNA解旋酶， 解旋酶II是大肠杆菌DNA复制和修复所必需。杆菌 E.大肠杆菌Rep解旋酶二元复合物 与（ss）DNA和与ss-DNA和ADP的三元复合物中， 分别测定为3.0 E和3.2 E的分辨率。 的 二元和三元配合物晶体中的不对称单元 含有两个Rep单体，由于重取向而彼此不同， 对应于旋转130度 关于铰链区。 这个大的运动导致关闭一个 参与ss-DNA结合的裂缝。 这样的领域运动， Rep二聚体的背景，足够大，表明这些 可以通过一个连接点与Rep二聚体沿着DNA的易位偶联。 子单元的逐步移动。 这些结构代表了 第一个观点的DNA解旋酶结合到DNA。

Rep DNA helicase is a DNA unwinding enzyme which together with helicase II is essential for DNA replication and repair in E. coli. Crystal structures of the E. coli Rep helicase in a binary complex with (ss) DNA and in a ternary complex with ss-DNA and ADP were determined to a resolution of 3.0 E and 3.2 E, respectively. The asymmetric unit in the crystals of the binary and ternary complexes contains two Rep monomers differing from each other by a reorientation of one of the domains, corresponding to a swiveling of 130 degree about a hinge region. This large motion results in the closing of a cleft involved in ss-DNA binding. Such domain movements, within the context of the Rep dimer, are sufficiently large to suggest that these may be coupled to translocation of the Rep dimer along DNA by a step-wise movement of the subunits. These structures represent the first view of a DNA helicase bound to DNA.