Microtubule end conversion mediated by motors and diffusing proteins with no intrinsic microtubule end-binding activity
Microtubule end conversion mediated by motors and diffusing proteins with no intrinsic microtubule end-binding activity
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DOI：
10.1038/s41467-019-09411-7
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发表时间：
2019-04-11
影响因子：
16.6
通讯作者：
Grishchuk, Ekaterina L.
中科院分区：
文献类型：
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作者：
Chakraborty, Manas;Tarasovetc, Ekaterina, V;Grishchuk, Ekaterina L.
准确的染色体分离依赖于微管末端转换，这是一种不为人所知的着丝点从侧向微管附着转移到与动态微管正端持久结合的能力。这种转化的分子要求和潜在的生物物理机制是难以捉摸的。我们在体外使用两种着丝点组分：正端定向的运动蛋白CENP-E和微管结合的Ndc80复合物，在微珠表面结合，重建了末端转化。CENP-E的主要作用是确保Ndc80复合物与微管正端之间的紧密接近，而Ndc80复合物通过扩散在微管尖端附近的微管壁上提供持久的微管结合。总之，在没有任何专门的尖端结合蛋白或调节蛋白的情况下，这些蛋白在几轮微管动力学过程中介导了强大的正端偶联。使用布朗动力学模型，我们表明端转换是微管壁结合蛋白的多分子集合具有精细调节的力依赖运动特性的紧急特性。
Accurate chromosome segregation relies on microtubule end conversion, the ill-understood ability of kinetochores to transit from lateral microtubule attachment to durable association with dynamic microtubule plus-ends. The molecular requirements for this conversion and the underlying biophysical mechanisms are elusive. We reconstituted end conversion in vitro using two kinetochore components: the plus end-directed kinesin CENP-E and microtubule-binding Ndc80 complex, combined on the surface of a microbead. The primary role of CENP-E is to ensure close proximity between Ndc80 complexes and the microtubule plus-end, whereas Ndc80 complexes provide lasting microtubule association by diffusing on the microtubule wall near its tip. Together, these proteins mediate robust plus-end coupling during several rounds of microtubule dynamics, in the absence of any specialized tip-binding or regulatory proteins. Using a Brownian dynamics model, we show that end conversion is an emergent property of multimolecular ensembles of microtubule wall-binding proteins with finely tuned force-dependent motility characteristics.