Thomas Ezekiel C, Moore Jeffrey K
Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
J Cell Biol. 2025 Mar 3;224(3). doi: 10.1083/jcb.202405115. Epub 2024 Dec 17.
The tubulin code hypothesis predicts that tubulin tails create programs for selective regulation of microtubule-binding proteins, including kinesin motors. However, the molecular mechanisms that determine selective regulation and their relevance in cells are poorly understood. We report selective regulation of budding yeast kinesin-5 motors by the β-tubulin tail. Cin8, but not Kip1, requires the β-tubulin tail for recruitment to the mitotic spindle, creating a balance of both motors in the spindle and efficient mitotic progression. We identify a negatively charged patch in the β-tubulin tail that mediates interaction with Cin8. Using in vitro reconstitution with genetically modified yeast tubulin, we demonstrate that the charged patch of β-tubulin tail increases Cin8 plus-end-directed velocity and processivity. Finally, we determine that the positively charged amino-terminal extension of Cin8 coordinates interactions with the β-tubulin tail. Our work identifies a molecular mechanism underlying selective regulation of closely related kinesin motors by tubulin tails and how this regulation promotes proper function of the mitotic spindle.
微管蛋白编码假说预测，微管蛋白尾部可为包括驱动蛋白马达在内的微管结合蛋白的选择性调控创建程序。然而，决定选择性调控的分子机制及其在细胞中的相关性却鲜为人知。我们报告了β-微管蛋白尾部对出芽酵母驱动蛋白-5马达的选择性调控。Cin8而非Kip1需要β-微管蛋白尾部才能被招募到有丝分裂纺锤体上，从而在纺锤体中实现两种马达的平衡以及高效的有丝分裂进程。我们在β-微管蛋白尾部鉴定出一个带负电荷的区域，该区域介导与Cin8的相互作用。通过使用基因改造的酵母微管蛋白进行体外重构，我们证明β-微管蛋白尾部的带电区域可提高Cin8向微管正端移动的速度和持续时间。最后，我们确定Cin8带正电荷的氨基末端延伸区域可协调与β-微管蛋白尾部的相互作用。我们的工作确定了微管蛋白尾部对密切相关的驱动蛋白马达进行选择性调控的分子机制，以及这种调控如何促进有丝分裂纺锤体的正常功能。
