Department of Biochemistry, University of Washington, Seattle, United States.
Department of Structural Biology, Genentech Inc, South San Francisco, United States.
Elife. 2020 May 14;9:e56582. doi: 10.7554/eLife.56582.
Partitioning duplicated chromosomes equally between daughter cells is a microtubule-mediated process essential to eukaryotic life. A multi-protein machine, the kinetochore, drives chromosome segregation by coupling the chromosomes to dynamic microtubule tips, even as the tips grow and shrink through the gain and loss of subunits. The kinetochore must harness, transmit, and sense mitotic forces, as a lack of tension signals incorrect chromosome-microtubule attachment and precipitates error correction mechanisms. But though the field has arrived at a 'parts list' of dozens of kinetochore proteins organized into subcomplexes, the path of force transmission through these components has remained unclear. Here we report reconstitution of functional kinetochore assemblies from recombinantly expressed proteins. The reconstituted kinetochores are capable of self-assembling in vitro, coupling centromeric nucleosomes to dynamic microtubules, and withstanding mitotically relevant forces. They reveal two distinct pathways of force transmission and Ndc80c recruitment.
将复制的染色体平均分配到子细胞中是真核生物生命所必需的微管介导过程。一个由多种蛋白质组成的机器——动粒，通过将染色体与动态微管尖端偶联，驱动染色体分离，即使尖端通过亚基的获得和丢失而生长和收缩。动粒必须利用、传递和感知有丝分裂力，因为缺乏张力会发出错误的染色体-微管连接信号，并引发错误修正机制。尽管该领域已经确定了数十种动粒蛋白组成的亚复合物的“部件清单”，但这些组件中的力传递途径仍然不清楚。在这里，我们报告了从重组表达蛋白中重新组装功能动粒组装体。重新组装的动粒能够在体外自我组装，将着丝粒核小体与动态微管偶联，并承受有丝分裂相关的力。它们揭示了两种不同的力传递途径和 Ndc80c 的募集。
