Sugata Kazunori, Nakamura Motoyoshi, Ueki Shoji, Fajer Peter G, Arata Toshiaki
Department of Biology, Graduate School of Science, Osaka University, Toyonaka, 560-0043 Osaka, Japan.
Biochem Biophys Res Commun. 2004 Feb 6;314(2):447-51. doi: 10.1016/j.bbrc.2003.12.093.
Conventional kinesin is a highly processive motor that converts the chemical energy of ATP hydrolysis into the unidirectional motility along microtubules. The processivity is thought to depend on the coordination between ATPase cycles of two motor domains and their neck linkers. Here we have used site-directed spin labeling electron spin resonance (SDSL-ESR) to determine the conformation of the neck linker in kinesin dimer in the presence and absence of microtubules. The spectra show that the neck linkers co-exist in both docked and disordered conformations, which is consistent with the results of monomeric kinesin. In all nucleotide states, however, the neck linkers are well ordered when dimeric kinesin is bound to the microtubule. This result suggests that the orientation of each neck linker that is fixed rigidly controls the kinesin motion along microtubule tracks.
传统的驱动蛋白是一种高度持续运动的分子马达，它将ATP水解的化学能转化为沿微管的单向运动。人们认为持续性依赖于两个马达结构域及其颈部连接体的ATP酶循环之间的协调。在这里，我们使用定点自旋标记电子自旋共振（SDSL-ESR）来确定在有和没有微管的情况下驱动蛋白二聚体中颈部连接体的构象。光谱表明，颈部连接体以对接和无序构象共存，这与单体驱动蛋白的结果一致。然而，在所有核苷酸状态下，当二聚体驱动蛋白与微管结合时，颈部连接体是有序排列的。这一结果表明，每个颈部连接体的刚性固定方向严格控制着驱动蛋白沿微管轨道的运动。
