Structures of microfilament destabilizing toxins bound to actin provide insight into toxin design and activity
Structures of microfilament destabilizing toxins bound to actin provide insight into toxin design and activity
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DOI：
10.1073/pnas.0502089102
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发表时间：
2005-10-11
影响因子：
11.1
通讯作者：
Rayment, I
中科院分区：
文献类型：
--
作者：
Allingham, JS;Zampella, A;Rayment, I
破坏肌动蛋白细胞骨架的海洋大环内酯类化合物是癌症治疗的有希望的候选者。在这里，我们展示了 reidispongiolide A 和 C 以及 sphinxolide B 的肌动蛋白结合 X 射线晶体结构，这三种海洋大环内酯是最近发现的细胞毒性化合物家族中发现的。它们的结构允许明确指定每种化合物的绝对构型。将它们的肌动蛋白结合位点与三异恶唑家族中发现的大环内酯以及二价大环内酯 swinholide A 进行比较，揭示了其大环的确定片段存在共同的结合表面。该表面位于与肌动蛋白倒刺末端的分隔结构域 1 和 3 的裂缝相邻的疏水片上。该表面周围的大面积容纳了在刺端靶向大环内酯的大环组分中观察到的多种构象和设计。相反，位于裂缝本身内的大环内酯尾部的结合口袋显示出非常有限的变化。通过使用体外肌动蛋白丝切断和聚合测定对这些大环内酯进行功能表征，证明了大环内酯尾部末端的 N-甲基-乙烯基甲酰胺部分对于毒素效力的必要性。这些分析还显示了大环与肌动蛋白上的疏水斑之间的稳定相互作用对于改变丝结构的重要性，以及大环内酯环组成的细微变化如何损害这种稳定性。通过识别这些复杂天然产物中构成其高肌动蛋白亲和力的基本成分，我们建立了设计新治疗剂的框架。
Marine macrolides that disrupt the actin cytoskeleton are promising candidates for cancer treatment. Here, we present the actin-bound x-ray crystal structures of reidispongiolide A and C and sphinxolide B, three marine macrolides found among a recently discovered family of cytotoxic compounds. Their structures allow unequivocal assignment of the absolute configuration for each compound. A comparison of their actin-binding site to macrolides found in the trisoxazole family, as well as the divalent macrolide, swinholide A, reveals the existence of a common binding surface for a defined segment of their macrocyclic ring. This surface is located on a hydrophobic patch adjacent to the cleft separating domains 1 and 3 at the barbed-end of actin. The large area surrounding this surface accommodates a wide variety of conformations and designs observed in the macrocyclic component of barbed-end-targeting macrolides. Conversely, the binding pocket for the macrolide tail, located within the cleft itself, shows very limited variation. Functional characterization of these macrolides by using in vitro actin filament severing and polymerization assays demonstrate the necessity of the N-methyl-vinylformamide moiety at the terminus of the macrolide tail for toxin potency. These analyses also show the importance of stable interactions between the macrocyclic ring and the hydrophobic patch on actin for modifying filament structure and how this stability can be compromised by subtle changes in macrolactone ring composition. By identifying the essential components of these complex natural products that underlie their high actin affinity, we have established a framework for designing new therapeutic agents.