Department of Genetics, University of Cambridge, Cambridge, UK.
Curr Biol. 2011 Mar 8;21(5):399-405. doi: 10.1016/j.cub.2011.02.005. Epub 2011 Feb 25.
Centromeres provide a region of chromatin upon which kinetochores are assembled in mitosis. Centromeric protein C (CENP-C) is a core component of this centromeric chromatin that, when depleted, prevents the proper formation of both centromeres and kinetochores. CENP-C localizes to centromeres throughout the cell cycle via its C-terminal part, whereas its N-terminal part appears necessary for recruitment of some but not all components of the Mis12 complex of the kinetochore. We now find that all kinetochore proteins belonging to the KMN (KNL1/Spc105, the Mis12 complex, and the Ndc80 complex) network bind to the N-terminal part of Drosophila CENP-C. Moreover, we show that the Mis12 complex component Nnf1 interacts directly with CENP-C in vitro. To test whether CENP-C's N-terminal part was sufficient to recruit KMN proteins, we targeted it to the centrosome by fusing it to a domain of Plk4 kinase. The Mis12 and Ndc80 complexes and Spc105 protein were then all recruited to centrosomes at the expense of centromeres, leading to mitotic abnormalities typical of cells with defective kinetochores. Thus, the N-terminal part of Drosophila CENP-C is sufficient to recruit core kinetochore components and acts as the principal linkage between centromere and kinetochore during mitosis.
着丝粒为动粒组装提供了染色质区域。着丝粒蛋白 C（CENP-C）是该着丝粒染色质的核心组成部分，当其缺失时，会阻止着丝粒和动粒的正确形成。CENP-C 通过其 C 端部分在整个细胞周期中定位到着丝粒，而其 N 端部分似乎对于招募动粒的 Mis12 复合物的一些但不是全部成分是必需的。现在我们发现，属于 KMN（KNL1/Spc105、Mis12 复合物和 Ndc80 复合物）网络的所有动粒蛋白都与果蝇 CENP-C 的 N 端部分结合。此外，我们还表明，Mis12 复合物成分 Nnf1 在体外与 CENP-C 直接相互作用。为了测试 CENP-C 的 N 端部分是否足以招募 KMN 蛋白，我们通过将其与 Plk4 激酶的一个结构域融合，将其靶向中心体。随后，Mis12 和 Ndc80 复合物以及 Spc105 蛋白都被招募到中心体，而不是着丝粒，导致具有缺陷动粒的细胞中典型的有丝分裂异常。因此，果蝇 CENP-C 的 N 端部分足以招募核心动粒成分，并在有丝分裂期间充当着丝粒和动粒之间的主要连接。
