Mutations in the genes that encode α- and β-tubulin underlie many neurological diseases, most notably malformations in cortical development (MCD). In addition to revealing the molecular basis for disease etiology, studying such mutations can provide insight into microtubule function, and the role of the large family of microtubule effectors. In this study, we use budding yeast to model one such mutation – Gly436Arg in α-tubulin, which is causative of MCD – in order to understand how it impacts microtubule function in a simple eukaryotic system. Using a combination of in vitro and in vivo methodologies, including live cell imaging and electron tomography, we find that the mutant tubulin incorporates into microtubules, causes a shift in α-tubulin isotype usage, and dramatically enhances dynein activity, which leads to spindle positioning defects. We find that the basis for this latter phenotype is an impaired interaction between She1 – a dynein inhibitor – and the mutant microtubules. In addition to revealing the natural balance of α-tubulin isotype utilization in cells, our results provide evidence of an impaired interaction between microtubules and a dynein regulator as a consequence of a tubulin mutation, and sheds light on a mechanism that may be causative of neurodevelopmental diseases.

编码 α- 和 β- 微管蛋白的基因突变是许多神经系统疾病的基础，最显着的是皮质发育畸形 (MCD)。除了揭示疾病病因的分子基础外，研究此类突变还可以深入了解微管功能以及微管效应子大家族的作用。在这项研究中，我们使用出芽酵母来模拟一种这样的突变——α-微管蛋白中的 Gly436Arg，它是 MCD 的原因——以了解它如何影响简单真核系统中的微管功能。使用体外和体内的组合方法，包括活细胞成像和电子断层扫描，我们发现突变的微管蛋白结合到微管中，导致α-微管蛋白同种型使用的转变，并显着增强动力蛋白活性，从而导致纺锤体定位缺陷。我们发现后一种表型的基础是 She1（一种动力蛋白抑制剂）与突变微管之间的相互作用受损。除了揭示细胞中 α-微管蛋白同种型利用的自然平衡之外，我们的结果还提供了微管蛋白突变导致微管和动力蛋白调节剂之间相互作用受损的证据，并阐明了可能导致神经发育的机制。疾病。