Biology Department, University of Massachusetts, Amherst, MA, USA.
Molecular and Cellular Biology Graduate Program, University of Massachusetts, Amherst, MA, USA.
J Cell Biol. 2024 Mar 4;223(3). doi: 10.1083/jcb.202211122. Epub 2024 Jan 5.
Kinetochores connect chromosomes and spindle microtubules to maintain genomic integrity through cell division. Crosstalk between the minus-end directed motor dynein and kinetochore-microtubule attachment factors promotes accurate chromosome segregation by a poorly understood pathway. Here, we identify a linkage between the intrinsically disordered protein Spc105 (KNL1 orthologue) and dynein using an optogenetic oligomerization assay. Core pools of the checkpoint protein BubR1 and the adaptor complex RZZ contribute to the linkage. Furthermore, a minimal segment of Spc105 with a propensity to multimerize and which contains protein binding motifs is sufficient to link Spc105 to RZZ/dynein. Deletion of the minimal region from Spc105 compromises the recruitment of its binding partners to kinetochores and elevates chromosome missegregation due to merotelic attachments. Restoration of normal chromosome segregation and localization of BubR1 and RZZ requires both protein binding motifs and oligomerization of Spc105. Together, our results reveal that higher-order multimerization of Spc105 contributes to localizing a core pool of RZZ that promotes accurate chromosome segregation.
动粒将染色体与纺锤体微管连接起来，通过细胞分裂维持基因组的完整性。负向指向的动力蛋白 dynein 与动粒微管连接因子之间的串扰通过一条尚未完全了解的途径促进了染色体的正确分离。在这里，我们使用光遗传学寡聚化测定法确定了内在无序蛋白 Spc105（KNL1 同源物）与 dynein 之间的联系。检查点蛋白 BubR1 和衔接复合物 RZZ 的核心池有助于这种联系。此外，一个具有多聚化倾向并包含蛋白结合基序的 Spc105 最小片段足以将 Spc105 与 RZZ/dynein 连接起来。Spc105 最小区域的缺失会损害其结合伴侣在动粒上的招募，并由于微管连接导致染色体错误分离。由于动粒连接，染色体分离和 BubR1 和 RZZ 的定位的恢复需要 Spc105 的蛋白结合基序和寡聚化。总之，我们的结果表明，Spc105 的高级多聚化有助于定位促进染色体正确分离的 RZZ 的核心池。
