Turner J, Anderson R, Guo J, Beraud C, Fletterick R, Sakowicz R
Department of Biochemistry and Biophysics, University of California, San Francisco, California 94143, USA.
J Biol Chem. 2001 Jul 6;276(27):25496-502. doi: 10.1074/jbc.M100395200. Epub 2001 Apr 27.
Success of mitosis depends upon the coordinated and regulated activity of many cellular factors, including kinesin motor proteins, which are required for the assembly and function of the mitotic spindle. Eg5 is a kinesin implicated in the formation of the bipolar spindle and its movement prior to and during anaphase. We have determined the crystal structure of the Eg5 motor domain with ADP-Mg bound. This structure revealed a new intramolecular binding site of the neck-linker. In other kinesins, the neck-linker has been shown to be a critical mechanical element for force generation. The neck-linker of conventional kinesin is believed to undergo an ordered-to-disordered transition as it translocates along a microtubule. The structure of Eg5 showed an ordered neck-linker conformation in a position never observed previously. The docking of the neck-linker relies upon residues conserved only in the Eg5 subfamily of kinesin motors. Based on this new information, we suggest that the neck-linker of Eg5 may undergo an ordered-to-ordered transition during force production. This ratchet-like mechanism is consistent with the biological activity of Eg5.
有丝分裂的成功取决于许多细胞因子的协同和调控活动，包括驱动蛋白运动蛋白，它们是有丝分裂纺锤体组装和功能所必需的。Eg5是一种与双极纺锤体形成及其在后期之前和期间的运动有关的驱动蛋白。我们已经确定了结合ADP-Mg的Eg5运动结构域的晶体结构。该结构揭示了颈链的一个新的分子内结合位点。在其他驱动蛋白中，颈链已被证明是产生力的关键机械元件。传统驱动蛋白的颈链被认为在沿着微管移动时会经历从有序到无序的转变。Eg5的结构显示颈链处于以前从未观察到的有序构象。颈链的对接依赖于仅在驱动蛋白运动蛋白的Eg5亚家族中保守的残基。基于这些新信息，我们认为Eg5的颈链在产生力期间可能会经历从有序到有序的转变。这种棘轮样机制与Eg5的生物学活性一致。
