Abstract：
The outer corona plays an essential role at the onset of mitosis by expanding to maximize microtubule attachment to kinetochores.1,2 The low-density structure of the corona forms through the expansion of unattached kinetochores. It comprises the RZZ complex, the dynein adaptor Spindly, the plus-end directed microtubule motor centromere protein E (CENP-E), and the Mad1/Mad2 spindle-assembly checkpoint proteins.3,4,5,6,7,8,9,10 CENP-E specifically associates with unattached kinetochores to facilitate chromosome congression,11,12,13,14,15,16 interacting with BubR1 at the kinetochore through its C-terminal region (2091-2358).17,18,19,20,21 We recently showed that CENP-E recruitment to BubR1 at the kinetochores is both rapid and essential for correct chromosome alignment. However, CENP-E is also recruited to the outer corona by a second, slower pathway that is currently undefined.19 Here, we show that BubR1-independent localization of CENP-E is mediated by a conserved loop that is essential for outer-corona targeting. We provide a structural model of the entire CENP-E kinetochore-targeting domain combining X-ray crystallography and Alphafold2. We reveal that maximal recruitment of CENP-E to unattached kinetochores critically depends on BubR1 and the outer corona, including dynein. Ectopic expression of the CENP-E C-terminal domain recruits the RZZ complex, Mad1, and Spindly, and prevents kinetochore biorientation in cells. We propose that BubR1-recruited CENP-E, in addition to its essential role in chromosome alignment to the metaphase plate, contributes to the recruitment of outer corona proteins through interactions with the CENP-E corona-targeting domain to facilitate the rapid capture of microtubules for efficient chromosome alignment and mitotic progression.
摘要：
外电晕在有丝分裂的开始中起着至关重要的作用，它通过扩大微管与动体的附着最大化。1,2电晕的低密度结构通过未附着的动体的扩张而形成。它包括RZZ复合体，动力蛋白适配器Spindly，正端定向微管运动着丝粒蛋白E（CENP-E），和Mad1/Mad2纺锤体组装检查点蛋白3,4,5,6,7,8,9,10CENP-E与未连接的动体特异性结合以促进染色体拥塞，11,12,13,14,15,16通过其C末端区域（2091-2358）在动子上与BubR1相互作用。17,18,19,20,21我们最近表明，CENP-E在动子上募集到BubR1对于正确的染色体排列既快速又必不可少。然而,CENP-E也被招募到外电晕一秒钟，目前未定义的较慢途径。19这里，我们表明CENP-E的BubR1非依赖性定位是由保守环介导的，这对于外冠靶向至关重要。我们结合X射线晶体学和Alphafold2提供了整个CENP-E动粒靶向域的结构模型。我们发现，CENP-E对未附着的动静脉的最大募集主要取决于BubR1和外电晕，包括动力蛋白.CENP-EC端结构域的异位表达募集RZZ复合物，Mad1和Spindly，并防止细胞中的动粒双向定向。我们建议BubR1招募的CENP-E，除了它在染色体与中期板对齐中的重要作用外，通过与CENP-E电晕靶向结构域的相互作用有助于募集外部电晕蛋白，以促进微管的快速捕获，以实现有效的染色体排列和有丝分裂进程。
