Microtubule polymerase and processive plus-end tracking functions originate from distinct features within TOG domain arrays.
Microtubule polymerase and processive plus-end tracking functions originate from distinct features within TOG domain arrays.
复制标题
微管聚合酶和进行性加端跟踪功能源自 TOG 域阵列内的不同特征。
DOI：
10.1091/mbc.e19-02-0093
复制
发表时间：
2019
影响因子：
3.3
通讯作者：
Al-Bassam,Jawdat
中科院分区：
文献类型：
--
作者：
Cook,BrianD;Chang,Fred;Flor-Parra,Ignacio;Al-Bassam,Jawdat
XMAP215/Stu2/Alp14 加速微管蛋白聚合，同时通过肿瘤过表达基因 (TOG) 结构域阵列逐步追踪微管 (MT) 末端。目前人们对这些功能是如何由不同的 TOG1 和 TOG2 结构域介导的微管蛋白募集产生的，或如何将这些阵列组装成大的方形复合物仍知之甚少。在这里，我们描述了 MT 加端跟踪和聚合酶功能之间的关系，揭示了它们在 TOG 阵列中的独特起源。我们研究基于结构模型设计的 Alp14 突变体，其在微管蛋白募集或自组织方面存在缺陷。使用裂殖酵母体内实时成像和体外 MT 动力学测定，我们表明 TOG1 和 TOG2 招募的微管蛋白在 MT 加端跟踪和聚合酶功能中发挥协调一致但又不同的作用。 TOG1 对于进行性加端追踪至关重要，而 TOG2 对于加速微管蛋白聚合至关重要。使方形复合物稳定的界面失活会导致进行性 MT 加端追踪和聚合酶的缺陷。我们的研究表明，方形和展开的 TOG 阵列状态之间的动态循环会引起 MT 加端的持续聚合酶活性。
XMAP215/Stu2/Alp14 accelerates tubulin polymerization while processively tracking microtubule (MT) plus ends via tumor overexpressed gene (TOG) domain arrays. It remains poorly understood how these functions arise from tubulin recruitment, mediated by the distinct TOG1 and TOG2 domains, or the assembly of these arrays into large square complexes. Here, we describe a relationship between MT plus-end tracking and polymerase functions revealing their distinct origin within TOG arrays. We study Alp14 mutants designed based on structural models, with defects in either tubulin recruitment or self-organization. Using in vivo live imaging in fission yeast and in vitro MT dynamics assays, we show that tubulins recruited by TOG1 and TOG2 serve concerted, yet distinct, roles in MT plus-end tracking and polymerase functions. TOG1 is critical for processive plus-end tracking, whereas TOG2 is critical for accelerating tubulin polymerization. Inactivating interfaces that stabilize square complexes lead to defects in both processive MT plus-end tracking and polymerase. Our studies suggest that a dynamic cycle between square and unfurled TOG array states gives rise to processive polymerase activity at MT plus ends.