Detection of sub-8-nm movements of kinesin by high-resolution optical-trap microscopy
Detection of sub-8-nm movements of kinesin by high-resolution optical-trap microscopy
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DOI：
10.1073/pnas.93.5.1913
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发表时间：
1996-03-05
影响因子：
11.1
通讯作者：
Vale, RD
中科院分区：
文献类型：
--
作者：
Coppin, CM;Finer, JT;Vale, RD
动蛋白是一种沿着微管运输细胞器的分子马达。这种酶有两个相同的7 nm长的运动域，它用来在沿着微管原丝间隔8 nm的连续微管蛋白结合位点之间移动。这种运动的分子机制尚待阐明，可能是所有马达蛋白家族共同的，在本研究中，高分辨率光学陷阱显微镜被用来直接测量单个Kinesin分子传输微观珠所产生的突然位移的大小，幅度的分布表明Kinesin不仅经历离散的8 nm运动，与以前的工作一致[Svoboda，K.，Schmidt，C.F.，Schnapp，B.J.&Block，S.M.(1993)Nature(London)365,721-727]，而且经常表现出约5 nm的较小运动。对于这些意想不到的较小运动，一个可能的解释是，驱动蛋白沿着原丝从一个二聚体到下一个二聚体的运动至少涉及机械循环中的两个不同事件。
Kinesin is a molecular motor that transports organelles along microtubules. This enzyme has two identical 7-nm-long motor domains, which it uses to move between consecutive tubulin binding sites spaced 8 nm apart along a microtubular protofilament. The molecular mechanism of this movement, which remains to be elucidated, may be common to all families of motor proteins, In this study, a high-resolution optical-trap microscope was used to measure directly the magnitude of abrupt displacements produced by a single kinesin molecule transporting a microscopic bead, The distribution of magnitudes reveals that kinesin not only undergoes discrete 8-nm movements, in agreement with previous work [Svoboda, K., Schmidt, C. F., Schnapp, B. J. & Block, S.M. (1993) Nature (London) 365, 721-727], but also frequently exhibits smaller movements of about 5 nm. A possible explanation for these unexpected smaller movements is that kinesin's movement from one dimer to the next along a protofilament involves at least two distinct events in the mechanical cycle.