Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK.
Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
J Cell Sci. 2020 Apr 29;133(8):jcs240978. doi: 10.1242/jcs.240978.
The kinetochore is a macromolecular protein complex that drives chromosome segregation in eukaryotes. Unlike most eukaryotes that have canonical kinetochore proteins, evolutionarily divergent kinetoplastids, such as , have unconventional kinetochore proteins. also lacks a canonical spindle checkpoint system, and it therefore remains unknown how mitotic progression is regulated in this organism. Here, we characterized, in the procyclic form of , two paralogous kinetochore proteins with a CLK-like kinase domain, KKT10 and KKT19, which localize at kinetochores in metaphase but disappear at the onset of anaphase. We found that these proteins are functionally redundant. Double knockdown of KKT10 and KKT19 led to a significant delay in the metaphase to anaphase transition. We also found that phosphorylation of two kinetochore proteins, KKT4 and KKT7, depended on KKT10 and KKT19 Finally, we showed that the N-terminal part of KKT7 directly interacts with KKT10 and that kinetochore localization of KKT10 depends not only on KKT7 but also on the KKT8 complex. Our results reveal that kinetochore localization of KKT10 and KKT19 is tightly controlled to regulate the metaphase to anaphase transition in This article has an associated First Person interview with the first author of the paper.
动粒是一种驱动真核生物染色体分离的大型蛋白质复合物。与大多数具有规范动粒蛋白的真核生物不同，进化上不同的动基体生物，如，具有非规范的动粒蛋白。也缺乏规范的纺锤体检查点系统，因此，尚不清楚有丝分裂进程如何在这个生物体中受到调节。在这里，我们在 的前鞭毛体形式中，表征了两个具有 CLK 样激酶结构域的动粒蛋白的同源物，KKT10 和 KKT19，它们在中期定位于动粒，但在后期开始时消失。我们发现这些蛋白质在功能上是冗余的。KKT10 和 KKT19 的双重敲低导致中期到后期过渡的显著延迟。我们还发现，两种动粒蛋白 KKT4 和 KKT7 的磷酸化依赖于 KKT10 和 KKT19。最后，我们表明 KKT7 的 N 端部分直接与 KKT10 相互作用，并且 KKT10 的动粒定位不仅取决于 KKT7，还取决于 KKT8 复合物。我们的结果表明，KKT10 和 KKT19 的动粒定位受到严格控制，以调节 中的中期到后期过渡。本文有与论文第一作者的相关第一人称采访。
