Department of Biochemistry, University of Washington, Seattle, WA.
Department of Physiology and Biophysics, University of Washington, Seattle, WA.
J Cell Biol. 2022 May 2;221(5). doi: 10.1083/jcb.202107016. Epub 2022 Mar 30.
Accurate mitosis requires kinetochores to make persistent, load-bearing attachments to dynamic microtubule tips, thereby coupling chromosome movements to tip growth and shortening. This tip-coupling behavior depends on the conserved Ndc80 complex and, in budding yeast, on the Dam1 complex, which bind each other directly via three distinct interacting regions. The functional relevance of these multiple interactions was mysterious. Here we show that interactions between two of these regions support the high rupture strengths that occur when applied force is rapidly increased and also support the stability of tip-coupling when force is held constant over longer durations. The contribution of either of these two regions to tip-coupling is reduced by phosphorylation by Aurora B kinase. The third interaction region makes no apparent contribution to rupture strength, but its phosphorylation by Aurora B kinase specifically decreases the long-term stability of tip-coupling. The specific reduction of long-term stability relative to short-term strength might have important implications for mitotic error correction.
准确的有丝分裂需要动粒与动态微管尖端持续、承重地连接，从而将染色体运动与尖端生长和缩短联系起来。这种尖端连接行为取决于保守的 Ndc80 复合物，在芽殖酵母中，还取决于 Dam1 复合物，它们通过三个不同的相互作用区域直接相互结合。这些多重相互作用的功能相关性一直是个谜。在这里，我们表明，这些区域中的两个区域之间的相互作用支持了当施加的力迅速增加时发生的高断裂强度，并且当力在较长时间内保持恒定时也支持了尖端连接的稳定性。这两个区域中的任何一个区域的相互作用对尖端连接的贡献都被 Aurora B 激酶的磷酸化所减少。第三个相互作用区域对断裂强度没有明显的贡献，但它被 Aurora B 激酶的磷酸化特异性地降低了尖端连接的长期稳定性。与短期强度相比，长期稳定性的特异性降低可能对有丝分裂错误校正具有重要意义。
