Department of Biophysics, University of Michigan, 930 N. University Avenue, Ann Arbor, MI 48109, USA.
Department of Cellular & Developmental Biology, University of Michigan, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA.
Curr Biol. 2020 Dec 21;30(24):4869-4881.e5. doi: 10.1016/j.cub.2020.09.038. Epub 2020 Oct 8.
The nanoscale protein architecture of the kinetochore plays an integral role in specifying the mechanisms underlying its functions in chromosome segregation. However, defining this architecture in human cells remains challenging because of the large size and compositional complexity of the kinetochore. Here, we use Förster resonance energy transfer to reveal the architecture of individual kinetochore-microtubule attachments in human cells. We find that the microtubule-binding domains of the Ndc80 complex cluster at the microtubule plus end. This clustering occurs only after microtubule attachment, and it increases proportionally with centromeric tension. Surprisingly, Ndc80 complex clustering is independent of the organization and number of its centromeric receptors. Moreover, this clustering is similar in yeast and human kinetochores despite significant differences in their centromeric organizations. These and other data suggest that the microtubule-binding interface of the human kinetochore behaves like a flexible "lawn" despite being nucleated by repeating biochemical subunits.
动粒的纳米级蛋白质结构在决定其在染色体分离中功能的机制方面起着重要作用。然而，由于动粒的体积大和组成复杂，在人细胞中定义这种结构仍然具有挑战性。在这里，我们使用Förster 共振能量转移来揭示人细胞中单个动粒-微管附着的结构。我们发现，Ndc80 复合物的微管结合域在微管的正端聚集。这种聚集仅在微管附着后发生，并且与着丝粒张力成比例增加。令人惊讶的是，Ndc80 复合物的聚类与它的着丝粒受体的组织和数量无关。此外，尽管它们的着丝粒组织存在显著差异，但酵母和人类动粒的这种聚类是相似的。这些和其他数据表明，尽管由重复的生化亚基起始，但人类动粒的微管结合界面表现得像一个灵活的“草坪”。
