Department of Molecular Cancer Research, University Medical Center Utrecht, 3584 CG Utrecht, Netherlands.
J Cell Biol. 2013 Apr 15;201(2):217-31. doi: 10.1083/jcb.201210033. Epub 2013 Apr 8.
The mitotic checkpoint ensures correct chromosome segregation by delaying cell cycle progression until all kinetochores have attached to the mitotic spindle. In this paper, we show that the mitotic checkpoint kinase MPS1 contains an N-terminal localization module, organized in an N-terminal extension (NTE) and a tetratricopeptide repeat (TPR) domain, for which we have determined the crystal structure. Although the module was necessary for kinetochore localization of MPS1 and essential for the mitotic checkpoint, the predominant kinetochore binding activity resided within the NTE. MPS1 localization further required HEC1 and Aurora B activity. We show that MPS1 localization to kinetochores depended on the calponin homology domain of HEC1 but not on Aurora B-dependent phosphorylation of the HEC1 tail. Rather, the TPR domain was the critical mediator of Aurora B control over MPS1 localization, as its deletion rendered MPS1 localization insensitive to Aurora B inhibition. These data are consistent with a model in which Aurora B activity relieves a TPR-dependent inhibitory constraint on MPS1 localization.
有丝分裂检查点通过延迟细胞周期进程，直到所有的着丝粒都连接到有丝分裂纺锤体，从而确保染色体的正确分离。在本文中，我们表明，有丝分裂检查点激酶 MPS1 含有一个 N 端定位模块，由 N 端延伸（NTE）和四肽重复（TPR）结构域组成，我们已经确定了其晶体结构。尽管该模块对于 MPS1 向着丝粒的定位以及有丝分裂检查点是必需的，但主要的着丝粒结合活性位于 NTE 内。MPS1 的定位还需要 HEC1 和 Aurora B 的活性。我们表明，MPS1 向着丝粒的定位取决于 HEC1 的钙调蛋白同源结构域，但不依赖于 Aurora B 对 HEC1 尾部的依赖性磷酸化。相反，TPR 结构域是 Aurora B 控制 MPS1 定位的关键介质，因为其缺失使得 MPS1 定位对 Aurora B 的抑制不敏感。这些数据与一个模型一致，即 Aurora B 的活性解除了 TPR 对 MPS1 定位的依赖性抑制约束。
