Tomishige Michio, Stuurman Nico, Vale Ronald D
Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
Nat Struct Mol Biol. 2006 Oct;13(10):887-94. doi: 10.1038/nsmb1151. Epub 2006 Oct 1.
Kinesin-1 is a dimeric motor protein that moves cargo processively along microtubules. Kinesin motility has been proposed to be driven by the coordinated forward extension of the neck linker (a approximately 12-residue peptide) in one motor domain and the rearward positioning of the neck linker in the partner motor domain. To test this model, we have introduced fluorescent dyes selectively into one subunit of the kinesin dimer and performed 'half-molecule' fluorescence resonance energy transfer to measure conformational changes of the neck linker. We show that when kinesin binds with both heads to the microtubule, the neck linkers in the rear and forward heads extend forward and backward, respectively. During ATP-driven motility, the neck linkers switch between these conformational states. These results support the notion that neck linker movements accompany the 'hand-over-hand' motion of the two motor domains.
驱动蛋白-1是一种二聚体马达蛋白，可沿微管持续移动货物。有人提出，驱动蛋白的运动是由一个马达结构域中颈部连接子（一段约12个残基的肽段）的协同向前延伸以及伙伴马达结构域中颈部连接子的向后定位驱动的。为了验证该模型，我们将荧光染料选择性地引入驱动蛋白二聚体的一个亚基中，并进行了“半分子”荧光共振能量转移，以测量颈部连接子的构象变化。我们发现，当驱动蛋白的两个头部都与微管结合时，后部和前部头部的颈部连接子分别向前和向后延伸。在ATP驱动的运动过程中，颈部连接子在这些构象状态之间切换。这些结果支持了颈部连接子运动伴随着两个马达结构域“交替式”运动的观点。
