Bannigan Alex, Scheible Wolf-Rüdiger, Lukowitz Wolfgang, Fagerstrom Carey, Wadsworth Patricia, Somerville Chris, Baskin Tobias I
Biology Department, University of Massachusetts, Amherst, MA 01003, USA.
J Cell Sci. 2007 Aug 15;120(Pt 16):2819-27. doi: 10.1242/jcs.009506. Epub 2007 Jul 24.
The mitotic spindle of vascular plants is assembled and maintained by processes that remain poorly explored at a molecular level. Here, we report that AtKRP125c, one of four kinesin-5 motor proteins in arabidopsis, decorates microtubules throughout the cell cycle and appears to function in both interphase and mitosis. In a temperature-sensitive mutant, interphase cortical microtubules are disorganized at the restrictive temperature and mitotic spindles are massively disrupted, consistent with a defect in the stabilization of anti-parallel microtubules in the spindle midzone, as previously described in kinesin-5 mutants from animals and yeast. AtKRP125c introduced into mammalian epithelial cells by transfection decorates microtubules throughout the cell cycle but is unable to complement the loss of the endogenous kinesin-5 motor (Eg5). These results are among the first reports of any motor with a major role in anastral spindle structure in plants and demonstrate that the conservation of kinesin-5 motor function throughout eukaryotes extends to vascular plants.
维管植物的有丝分裂纺锤体是通过在分子水平上仍未得到充分探索的过程组装和维持的。在这里，我们报告拟南芥中四种驱动蛋白-5运动蛋白之一的AtKRP125c在整个细胞周期中都与微管结合，并且似乎在间期和有丝分裂中都发挥作用。在一个温度敏感突变体中，在限制温度下，间期皮层微管紊乱，有丝分裂纺锤体大量破坏，这与纺锤体中间区反平行微管的稳定缺陷一致，正如之前在动物和酵母的驱动蛋白-5突变体中所描述的那样。通过转染导入哺乳动物上皮细胞的AtKRP125c在整个细胞周期中都与微管结合，但无法弥补内源性驱动蛋白-5运动蛋白（Eg5）的缺失。这些结果是关于任何在植物无星纺锤体结构中起主要作用的运动蛋白的首批报道之一，并证明驱动蛋白-5运动蛋白功能在整个真核生物中的保守性延伸到了维管植物。
