Abouelghar Ahmed A, Carrier Joseph S, Torvi Julia R, Jenson Erin, Jones Chloe, Gangadharan Binnu, Prinslow Elisabeth G, Rice Luke M, Lagesse Brent, Barnes Georjana, Miller Matthew P
Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT, USA.
Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA.
J Cell Biol. 2025 Oct 6;224(10). doi: 10.1083/jcb.202209025. Epub 2025 Sep 3.
ch-TOG family proteins, including the budding yeast Stu2, are essential for spindle formation and chromosome segregation. Such functions depend on an array of activities ranging from microtubule nucleation, polymerization, and depolymerization to conferring tension sensitivity to kinetochores. This functional diversity makes it challenging to dissect these various functions and understand their relative importance. Here, we developed separation-of-function mutants and used artificial tethering tools to elucidate several important mechanistic insights into Stu2's essential role. We show that Stu2's microtubule polymerization activity depends on its basic linker region but is surprisingly dispensable for viability; that in fact, Stu2 carries out an essential kinetochore-associated function; and finally, that Stu2's precise location within the kinetochore is critical for its function, suggesting a spatial separation mode of action may underlie its ability to confer tension sensitivity. Our findings highlight the significance of Stu2's kinetochore role and provide insights into the molecular mechanisms by which it performs its various functions.
包括出芽酵母Stu2在内的ch-TOG家族蛋白对于纺锤体形成和染色体分离至关重要。这些功能依赖于一系列活动，从微管成核、聚合和解聚到赋予动粒张力敏感性。这种功能多样性使得剖析这些不同功能并理解它们的相对重要性具有挑战性。在这里，我们开发了功能分离突变体并使用人工拴系工具来阐明关于Stu2重要作用的几个重要机制见解。我们表明，Stu2的微管聚合活性取决于其基本连接区，但令人惊讶的是，对于细胞存活而言并非必需；事实上，Stu2执行一种与动粒相关的基本功能；最后，Stu2在动粒内的精确位置对其功能至关重要，这表明空间分离作用模式可能是其赋予张力敏感性能力的基础。我们的发现突出了Stu2在动粒中作用的重要性，并为其执行各种功能的分子机制提供了见解。
