Interactions of halichondrin B and eribulin with tubulin.
Interactions of halichondrin B and eribulin with tubulin.
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DOI：
10.1021/ci200077t
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发表时间：
2011-06-27
影响因子：
5.6
通讯作者：
Hamel E
中科院分区：
文献类型：
--
作者：
Bai R;Nguyen TL;Burnett JC;Atasoylu O;Munro MH;Pettit GR;Smith AB 3rd;Gussio R;Hamel E
调节微管动力学的化合物包括高效的抗癌药物，导致继续努力识别新的药物并改善已建立的药物的活性。在这里，我们证明了[3 H]-标记的软海绵素B（HB），一种复杂的，海绵衍生的天然产物，在每个αβ-异源二聚体的一个结合位点与微管蛋白快速结合和解离，表观Kd为0.31 μM。我们发现没有HB诱导的微管蛋白聚集的高效液相色谱法，即使在柱平衡HB。[3 H]HB的结合被一种新批准的临床药物，截短的HB类似物艾日布林（表观Ki，0.80 μM）竞争性抑制，而被多拉司他汀10和长春新碱非竞争性抑制（表观Ki分别为0.35和5.4 μM）。我们早期的研究表明，HB抑制β-微管蛋白上的核苷酸交换，这与这里提供的结果一起表明HB位点位于β-微管蛋白上。使用分子动力学模拟，我们确定了HB和β-微管蛋白的互补构象，以原子细节描绘了HB与仅β-微管蛋白的结合相互作用，而α-亚基不参与结合相互作用。此外，HB模型作为艾日布林结合模型的模板，进一步加深了我们对艾日布林作为药物的性质的理解。总之，这些结果为软海绵素类化合物的抗有丝分裂活性建立了机制基础。
Compounds that modulate microtubule dynamics include highly effective anticancer drugs, leading to continuing efforts to identify new agents and improve the activity of established ones. Here, we demonstrate that [3H]-labeled halichondrin B (HB), a complex, sponge-derived natural product, is bound to and dissociated from tubulin rapidly at one binding site per αβ-heterodimer, with an apparent Kd of 0.31 μM. We found no HB-induced aggregation of tubulin by high-performance liquid chromatography, even following column equilibration with HB. Binding of [3H]HB was competitively inhibited by a newly approved clinical agent, the truncated HB analogue eribulin (apparent Ki, 0.80 μM) and noncompetitively by dolastatin 10 and vincristine (apparent Ki’s, 0.35 and 5.4 μM, respectively). Our earlier studies demonstrated that HB inhibits nucleotide exchange on β-tubulin, and this, together with the results presented here, indicated the HB site is located on β-tubulin. Using molecular dynamics simulations, we determined complementary conformations of HB and β-tubulin that delineated in atomic detail binding interactions of HB with only β-tubulin, with no involvement of the α-subunit in the binding interaction. Moreover, the HB model served as a template for an eribulin binding model that furthered our understanding of the properties of eribulin as a drug. Overall, these results established a mechanistic basis for the antimitotic activity of the halichondrin class of compounds.