Kinesin-6 Klp9 plays motor-dependent and -independent roles in collaboration with Kinesin-5 Cut7 and the microtubule crosslinker Ase1 in fission yeast
Kinesin-6 Klp9 plays motor-dependent and -independent roles in collaboration with Kinesin-5 Cut7 and the microtubule crosslinker Ase1 in fission yeast
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DOI：
10.1038/s41598-019-43774-7
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发表时间：
2018-11
影响因子：
4.6
通讯作者：
M. Yukawa;Masaki Okazaki;Yasuhiro Teratani;Ken’ya Furuta;T. Toda
中科院分区：
文献类型：
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作者：
M. Yukawa;Masaki Okazaki;Yasuhiro Teratani;Ken’ya Furuta;T. Toda
两极有丝分裂纺锤体在精确的染色体分离中起着关键作用。在有丝分裂后期，纺锤体微管在一个称为后期B的过程中经历剧烈的伸长，两个动蛋白马达，kinesin-5和kinesin-6，被认为产生外力来驱动纺锤体的伸长，而微管交联剂Ase1/PRc1维持反平行微管的结构完整性。然而，这三种蛋白质如何协调这一过程仍不清楚。在这里，我们探讨了裂解酵母Kinesin-5/Cut7、Kinesin-6/Klp9和Ase1之间的功能相互作用。在全内反射荧光显微镜下，我们证明了Klp9形成同源四聚体，Klp9是一种进行性加末端定向的运动。Klp9Δase1Δ具有合成致死性。令人惊讶的是，这种致命性不能归因于Klp9有缺陷的运动活动；相反，它依赖于核定位信号和非运动区内的螺旋线圈结构域。我们分离到一个突变体(ut7-122)，它只在没有Klp9的情况下表现出温度敏感性。有趣的是，Cut7-122单独在后期B的纺锤体伸长中受损，而且Cut7-122klp9Δ双突变体表现出加性缺陷。我们认为Klp9在B期后期具有双重作用：一种是运动依赖的，与Cut7协同产生力量；另一种是运动非依赖的，与Ase1一起确保纺锤体微管结构的完整性。
Bipolar mitotic spindles play a critical part in accurate chromosome segregation. During late mitosis, spindle microtubules undergo drastic elongation in a process called anaphase B. Two kinesin motors, Kinesin-5 and Kinesin-6, are thought to generate outward forces to drive spindle elongation, and the microtubule crosslinker Ase1/PRC1 maintains structural integrity of antiparallel microtubules. However, how these three proteins orchestrate this process remains unknown. Here we explore the functional interplay among fission yeast Kinesin-5/Cut7, Kinesin-6/Klp9 and Ase1. Using total internal reflection fluorescence microscopy, we show that Klp9 forms homotetramers and that Klp9 is a processive plus end-directed motor.klp9Δase1Δis synthetically lethal. Surprisingly, this lethality is not ascribable to the defective motor activity of Klp9; instead, it is dependent upon a nuclear localisation signal and coiled coil domains within the non-motor region. We isolated acut7mutant (cut7-122) that displays temperature sensitivity only in the absence of Klp9. Interestingly,cut7-122alone is impaired in spindle elongation during anaphase B, and furthermore,cut7-122klp9Δdouble mutants exhibit additive defects. We propose that Klp9 plays dual roles during anaphase B; one is motor-dependent that collaborates with Cut7 in force generation, while the other is motor-independent that ensures structural integrity of spindle microtubules together with Ase1.