NUCLEOTIDE-DEPENDENT ANGULAR CHANGE IN KINESIN MOTOR DOMAIN BOUND TO TUBULIN
NUCLEOTIDE-DEPENDENT ANGULAR CHANGE IN KINESIN MOTOR DOMAIN BOUND TO TUBULIN
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DOI：
10.1038/376277a0
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发表时间：
1995-07-20
期刊：
影响因子：
64.8
通讯作者：
AMOS, LA
中科院分区：
文献类型：
--
作者：
HIROSE, K;LOCKHART, A;AMOS, LA
激动素是一种“马达”分子，由两个头部结构域、一个α-螺旋卷曲螺旋杆和一个与其货物结合的尾部组成（1，2）。当在细菌系统中表达时，头部结构域是功能性的（3），并且可以以每个微管蛋白二聚体一个头部的化学计量与微管结合。驱动蛋白通过核苷酸结合、水解和产物释放的循环过程沿着微管移动（4，5）。我们使用负染电子显微镜和图像分析来研究微管和微管蛋白片的结构，这些微管和微管蛋白片在三种状态下被驱动蛋白的马达结构域（珠）修饰：在存在不可水解的ATP类似物5 '-腺苷酰亚胺二磷酸（AMP-PNP）的情况下;没有核苷酸的情况下;和有腺苷5'-二磷酸（ADP）的情况下。与微管结合的单个驱动蛋白头部具有梨形结构，在所有条件下，较宽的一端朝向微管的“正”端;反向马达ncd也具有类似的方向。三维图谱显示，驱动蛋白头部有一个尖峰，据推测该尖峰与完整驱动蛋白分子的尾部形成连接。该尖峰在ADP存在下垂直于微管轴，但在AMP-PNP存在或不存在核苷酸的情况下指向正端（类似于45度）。我们的研究结果提供了直接的证据，在ATP酶循环的驱动蛋白运动域的构象变化。
KINESIN is a 'motor' molecule, consisting of two head domains, an alpha-helical coiled coil rod, and a tail part that binds to its cargo(1,2). When expressed in a bacterial system, the head domain is functional(3), and can bind to microtubules with the stoichiometry of one head per tubulin dimer. Kinesin moves along microtubules by means of a cyclic process of nucleotide binding, hydrolysis and product release(4,5). We have used negative-stain electron microscopy and image analysis to study the structures of microtubules and tubulin sheets decorated with the motor domain (bead) of kinesin in three states: in the presence of an unhydrolysable ATP analogue, 5'-adenylylimidodiphosphate (AMP-PNP); without nucleotides; and with adenosine 5'-diphosphate (ADP). A single kinesin head bound to a microtubule has a pear-shaped structure, with the broader end towards the 'plus' end of the microtubule under all conditions; the reverse motor, ncd, is similarly oriented. Three-dimensional maps reveal that kinesin heads have a spike that is assumed to form the attachment to the tail of a complete kinesin molecule. This spike is perpendicular to the microtubule axis in the presence of ADP, but points towards the plus end (similar to 45 degrees) in the presence of AMP-PNP or absence of nucleotides. Our results provide direct evidence for a conformational change of the kinesin motor domain during the ATPase cycle.