Department of Molecular Genetics, Faculty of Biology, University of Duisburg-Essen, Universitätsstrasse 5, 45117 Essen, Germany; Center of Medical Biotechnology, University of Duisburg-Essen, Universitätsstrasse 5, 45117 Essen, Germany.
Department of Chemical Biology and ACE Analytical Core Facility Essen, Faculty of Biology, University of Duisburg-Essen, Universitätsstrasse 5, 45117 Essen, Germany; Center of Medical Biotechnology, University of Duisburg-Essen, Universitätsstrasse 5, 45117 Essen, Germany.
Curr Biol. 2024 Jun 3;34(11):2279-2293.e6. doi: 10.1016/j.cub.2024.03.062. Epub 2024 May 21.
Faithful chromosome segregation requires that sister chromatids establish bi-oriented kinetochore-microtubule attachments. The spindle assembly checkpoint (SAC) prevents premature anaphase onset with incomplete attachments. However, how microtubule attachment and checkpoint signaling are coordinated remains unclear. The conserved kinase Mps1 initiates SAC signaling by localizing transiently to kinetochores in prometaphase and is released upon bi-orientation. Using biochemistry, structure predictions, and cellular assays, we shed light on this dynamic behavior in Saccharomyces cerevisiae. A conserved N-terminal segment of Mps1 binds the neck region of Ndc80:Nuf2, the main microtubule receptor of kinetochores. Mutational disruption of this interface, located at the backside of the paired CH domains and opposite the microtubule-binding site, prevents Mps1 localization, eliminates SAC signaling, and impairs growth. The same interface of Ndc80:Nuf2 binds the microtubule-associated Dam1 complex. We demonstrate that the error correction kinase Ipl1/Aurora B controls the competition between Dam1 and Mps1 for the same binding site. Thus, binding of the Dam1 complex to Ndc80:Nuf2 may release Mps1 from the kinetochore to promote anaphase onset.
姐妹染色单体的正确分离需要其建立双定向的动粒-微管连接。纺锤体组装检查点（SAC）通过阻止未完全连接的染色体发生过早的后期来防止该过程的发生。然而，微管连接和检查点信号如何协调仍不清楚。保守激酶 Mps1 通过在前期短暂定位于动粒来启动 SAC 信号，在双定向后被释放。我们通过生物化学、结构预测和细胞测定，阐明了酿酒酵母中这一动态行为。Mps1 的保守 N 端片段与 Ndc80:Nuf2 的颈部区域结合，后者是动粒的主要微管受体。位于成对的 CH 结构域背面且与微管结合位点相对的该界面的突变破坏会阻止 Mps1 的定位，消除 SAC 信号，并损害生长。Ndc80:Nuf2 的相同界面与微管相关的 Dam1 复合物结合。我们证明，错误校正激酶 Ipl1/Aurora B 控制着 Dam1 和 Mps1 对同一结合位点的竞争。因此，Dam1 复合物与 Ndc80:Nuf2 的结合可能会将 Mps1 从动粒上释放出来，从而促进后期的开始。
