Kaseda Kuniyoshi, Higuchi Hideo, Hirose Keiko
Gene Function Research Center, National Institute of Advanced Industrial Science and Technology and Japan Society for the Promotion of Science, Tsukuba, Ibaraki 305-8562, Japan.
Nat Cell Biol. 2003 Dec;5(12):1079-82. doi: 10.1038/ncb1067. Epub 2003 Nov 23.
A conventional kinesin molecule travels continuously along a microtubule in discrete 8-nm steps. This processive movement is generally explained by models in which the two identical heads of a kinesin move in a 'hand-over-hand' manner. Here, we show that a single heterodimeric kinesin molecule (in which one of the two heads is mutated in a nucleotide-binding site) exhibits fast and slow (with the dwell time at least 10 times longer than that of the fast step) 8-nm steps alternately, presumably corresponding to the displacement by the wild-type and mutant heads, respectively. Our results provide the first direct evidence for models in which the roles of the two heads alternate every 8-nm step.
传统的驱动蛋白分子沿着微管以8纳米的离散步长持续移动。这种持续性运动通常由一些模型来解释，在这些模型中，驱动蛋白的两个相同头部以“手拉手”的方式移动。在这里，我们表明，单个异源二聚体驱动蛋白分子（其中两个头部之一在核苷酸结合位点发生突变）交替展示出快速和慢速（停留时间至少比快速步长的停留时间长10倍）的8纳米步长，推测分别对应野生型和突变型头部的位移。我们的结果为两个头部的作用每8纳米步长交替的模型提供了首个直接证据。
