Structure of the human outer kinetochore KMN network complex
Structure of the human outer kinetochore KMN network complex
复制标题
DOI：
10.1038/s41594-024-01249-y
复制
发表时间：
2024-03-08
影响因子：
16.8
通讯作者：
Barford，David
中科院分区：
文献类型：
--
作者：
Yatskevich，Stanislau;Yang，Jing;Barford，David
忠实的染色体分离需要染色体与有丝分裂纺锤体牢固的、承重的连接，这一功能是由称为动粒的大分子复合物完成的。在大多数真核生物中，内部动粒的组成型着丝粒相关网络（CCAN）复合物将包含KNL 1C、MIS 12 C和NDC 80 C复合物的10个亚基的外部动粒KMN网络募集到着丝粒。KMN网络通过MIS 12 C和NDC 80 C将CCAN直接连接到微管。在这里，我们确定了人类KMN网络的高分辨率cryo-EM结构。这显示了KMN亚基的复杂和广泛的组装，其中中心MIS 12 C与NDC 80 C和KNL 1C形成刚性界面，并通过多个肽亚基间连接而增强。我们还观察到，未磷酸化的MIS 12 C存在于自抑制状态，抑制其与CCAN相互作用的能力。MIS 12 C亚基Dsn 1的N-末端片段的Ser 100和Ser 109是Aurora B激酶的两个关键靶点，直接稳定这种自抑制。我们的研究表明，如何选择性地缓解这种自抑制通过Ser 100和Ser 109磷酸化可能会限制外动粒组装功能着丝粒在细胞分裂。
Faithful chromosome segregation requires robust, load-bearing attachments of chromosomes to the mitotic spindle, a function accomplished by large macromolecular complexes termed kinetochores. In most eukaryotes, the constitutive centromere-associated network (CCAN) complex of the inner kinetochore recruits to centromeres the ten-subunit outer kinetochore KMN network that comprises the KNL1C, MIS12C and NDC80C complexes. The KMN network directly attaches CCAN to microtubules through MIS12C and NDC80C. Here, we determined a high-resolution cryo-EM structure of the human KMN network. This showed an intricate and extensive assembly of KMN subunits, with the central MIS12C forming rigid interfaces with NDC80C and KNL1C, augmented by multiple peptidic inter-subunit connections. We also observed that unphosphorylated MIS12C exists in an auto-inhibited state that suppresses its capacity to interact with CCAN. Ser100 and Ser109 of the N-terminal segment of the MIS12C subunit Dsn1, two key targets of Aurora B kinase, directly stabilize this auto-inhibition. Our study indicates how selectively relieving this auto-inhibition through Ser100 and Ser109 phosphorylation might restrict outer kinetochore assembly to functional centromeres during cell division.