Department of Experimental Oncology, European Institute of Oncology (IEO), Milan, Italy.
J Cell Biol. 2010 Sep 6;190(5):835-52. doi: 10.1083/jcb.201002070.
Kinetochores are nucleoprotein assemblies responsible for the attachment of chromosomes to spindle microtubules during mitosis. The KMN network, a crucial constituent of the outer kinetochore, creates an interface that connects microtubules to centromeric chromatin. The NDC80, MIS12, and KNL1 complexes form the core of the KMN network. We recently reported the structural organization of the human NDC80 complex. In this study, we extend our analysis to the human MIS12 complex and show that it has an elongated structure with a long axis of approximately 22 nm. Through biochemical analysis, cross-linking-based methods, and negative-stain electron microscopy, we investigated the reciprocal organization of the subunits of the MIS12 complex and their contacts with the rest of the KMN network. A highlight of our findings is the identification of the NSL1 subunit as a scaffold supporting interactions of the MIS12 complex with the NDC80 and KNL1 complexes. Our analysis has important implications for understanding kinetochore organization in different organisms.
着丝粒是有丝分裂过程中负责将染色体附着到纺锤体微管上的核蛋白组装体。KMN 网络是外着丝粒的重要组成部分，它形成了连接微管和着丝粒染色质的界面。NDC80、MIS12 和 KNL1 复合物构成了 KMN 网络的核心。我们最近报道了人类 NDC80 复合物的结构组织。在这项研究中，我们将分析扩展到人类 MIS12 复合物，并表明它具有约 22nm 的长轴的拉长结构。通过生化分析、基于交联的方法和负染电子显微镜，我们研究了 MIS12 复合物亚基的相互组织及其与 KMN 网络其余部分的接触。我们研究的一个重点是确定 NSL1 亚基作为支架，支持 MIS12 复合物与 NDC80 和 KNL1 复合物的相互作用。我们的分析对于理解不同生物体中的着丝粒组织具有重要意义。
