Mechanism of microtubule stabilization by taccalonolide AJ.
Mechanism of microtubule stabilization by taccalonolide AJ.
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他卡洛内酯 AJ 稳定微管的机制
DOI：
10.1038/ncomms15787
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发表时间：
2017-06-06
影响因子：
16.6
通讯作者：
Yang J
中科院分区：
文献类型：
--
作者：
Wang Y;Yu Y;Li GB;Li SA;Wu C;Gigant B;Qin W;Chen H;Wu Y;Chen Q;Yang J
作为细胞骨架的主要组成部分，微管由αβ - 微管蛋白异二聚体构成，已被视为极具潜力的癌症化疗靶点。微管稳定剂（MSAs）可促进微管蛋白聚合并稳定聚合物，防止其解聚。然而，MSAs稳定微管的分子机制仍不明确。在此，我们报道了微管蛋白与塔卡醇内酯AJ（一种新发现的紫杉烷位点MSA）复合物的2.05 Å晶体结构。塔卡醇内酯AJ与β - 微管蛋白的D226共价结合。AJ结合后，M环发生构象转变，以促进微管蛋白聚合。在这种微管蛋白 - AJ复合物中，微管蛋白的E位点被GTP而非GDP占据。生化分析证实，AJ抑制E位点GTP的水解。因此，我们提出，β - 微管蛋白E位点因AJ的结合而锁定在偏好GTP的状态。我们的研究结果为MSA结合与微管蛋白核苷酸状态之间的联系提供了实验证据，将有助于设计新的MSAs以克服紫杉烷耐药性。
微管稳定剂（MSAs）促进微管蛋白聚合，作为抗癌药物备受关注。本文作者展示了MSA塔卡醇内酯AJ与微管蛋白结合的晶体结构，并深入解析了其作用模式，这可能有助于新型MSAs的设计。
As a major component of the cytoskeleton, microtubules consist of αβ-tubulin heterodimers and have been recognized as attractive targets for cancer chemotherapy. Microtubule-stabilizing agents (MSAs) promote polymerization of tubulin and stabilize the polymer, preventing depolymerization. The molecular mechanisms by which MSAs stabilize microtubules remain elusive. Here we report a 2.05 Å crystal structure of tubulin complexed with taccalonolide AJ, a newly identified taxane-site MSA. Taccalonolide AJ covalently binds to β-tubulin D226. On AJ binding, the M-loop undergoes a conformational shift to facilitate tubulin polymerization. In this tubulin–AJ complex, the E-site of tubulin is occupied by GTP rather than GDP. Biochemical analyses confirm that AJ inhibits the hydrolysis of the E-site GTP. Thus, we propose that the β-tubulin E-site is locked into a GTP-preferred status by AJ binding. Our results provide experimental evidence for the connection between MSA binding and tubulin nucleotide state, and will help design new MSAs to overcome taxane resistance. Microtubule-stabilizing agents (MSAs) promote the polymerization of tubulin and are of great interest as anticancer drugs. Here the authors present the crystal structure of the MSA taccalonolide AJ bound to tubulin and give insights into its mode of action, which might help in the design of novel MSAs.