Centromere/kinetochore is assembled through CENP-C oligomerization. Hara et al

The kinetochore is an essential protein complex required for accurate chromosome segregation. The constitutive centromere-associated network (CCAN), a subcomplex of the kinetochore, associates with centromeric chromatin and provides a platform for the kinetochore assembly. The CCAN protein CENP-C is thought to be a central hub for the centromere/kinetochore organization. However, the role of CENP-C in CCAN assembly needs to be elucidated. Here, we demonstrate that both the CCAN-binding domain and the C-terminal region that includes the Cupin domain of CENP-C are necessary and sufficient for chicken CENP-C function. Structural and biochemical analyses reveal self-oligomerization of the Cupin domains of chicken and human CENP-C. We find that the CENP-C Cupin domain oligomerization is vital for CENP-C function, centromeric localization of CCAN, and centromeric chromatin organization. These results suggest that CENP-C facilitates the centromere/kinetochore assembly through its oligomerization.

动粒（kinetochore）是实现精准染色体分离所必需的关键蛋白质复合物。组成型着丝粒相关网络（CCAN）作为动粒的亚复合物，可结合着丝粒染色质，并为动粒组装提供核心平台。组成型着丝粒相关网络中的着丝粒蛋白C（CENP-C）被认为是介导着丝粒/动粒组织的核心枢纽。然而，CENP-C在CCAN组装过程中的具体作用仍有待阐明。本研究证实，鸡源着丝粒蛋白C（CENP-C）的功能同时依赖其CCAN结合结构域与包含杯状结构域（Cupin domain）的C端区域，且二者兼具即可满足其功能发挥的需求。结构与生化分析显示，鸡源与人类CENP-C的杯状结构域均可发生自身寡聚化。研究发现，CENP-C的杯状结构域寡聚化，对于CENP-C发挥功能、CCAN的着丝粒定位以及着丝粒染色质组织均具有至关重要的作用。上述结果表明，CENP-C可通过其自身寡聚化特性促进着丝粒/动粒的组装过程。