Henningsen U, Schliwa M
Adolf-Butenandt-Institut, Zellbiologie, University of Munich, Germany.
Nature. 1997 Sep 4;389(6646):93-6. doi: 10.1038/38022.
Kinesin and non-claret disjunctional (ncd) are molecular motors of the kinesin superfamily that move in opposite directions along microtubules. The molecular basis underlying the direction of movement is unclear, although it is thought to be an intrinsic property of the motor domain, a conserved region about 330 amino acids in length. The motor domain is found at the amino terminus in conventional kinesins, but at the carboxy terminus in ncd. Here we report on a chimaera composed of the motor domain of the minus-end-directed kinesin of Neurospora crassa. The bacterially expressed fusion protein was tested in motility assays using polarity-marked microtubules. Surprisingly, the chimaera moved towards the plus end, demonstrating that the polarity of force generation of the ncd motor domain has been reversed. This finding indicates that the domain organization, particularly the position of the motor domain, is of fundamental importance for the polarity of force production. It also demonstrates that the direction of microtubule movement is not controlled solely by the motor domain.
驱动蛋白和非红化分离蛋白（ncd）是驱动蛋白超家族的分子马达，它们沿微管向相反方向移动。尽管人们认为运动方向的分子基础是马达结构域的固有特性，该结构域是一个长度约为330个氨基酸的保守区域，但目前尚不清楚其背后的分子基础。在传统驱动蛋白中，马达结构域位于氨基末端，但在ncd中位于羧基末端。在这里，我们报道了一种由粗糙脉孢菌负端定向驱动蛋白的马达结构域组成的嵌合体。使用带有极性标记的微管在运动分析中对细菌表达的融合蛋白进行了测试。令人惊讶的是，该嵌合体向正端移动，这表明ncd马达结构域产生力的极性已经反转。这一发现表明，结构域组织，特别是马达结构域的位置，对于力产生的极性至关重要。它还表明微管运动的方向并非仅由马达结构域控制。
