A chemical compound inhibiting the Aha1–Hsp90 chaperone complex
A chemical compound inhibiting the Aha1–Hsp90 chaperone complex
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DOI：
10.1074/jbc.m117.797829
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发表时间：
2017-08
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影响因子：
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通讯作者：
S. Stiegler;M. Rübbelke;V. Korotkov;M. Weiwad;C. John;G. Fischer;S. Sieber;M. Sattler;J. Buchner
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作者：
S. Stiegler;M. Rübbelke;V. Korotkov;M. Weiwad;C. John;G. Fischer;S. Sieber;M. Sattler;J. Buchner
真核 Hsp90 分子伴侣机制包含许多辅助分子伴侣，并调节数百种胞质客户蛋白的构象。因此，Hsp90 机制成为癌症等疾病的有吸引力的治疗靶点也就不足为奇了。迄今为止用于靶向该机制的化合物影响整个 Hsp90 系统。然而，我们希望实现 Hsp90-共伴侣复合物的更具选择性的靶向。为了测试这个概念，在这项原理验证研究中，我们筛选了 Hsp90 与其共伴侣 Aha1 之间相互作用的调节剂，该调节剂可加速 Hsp90 的 ATP 酶活性。基于 FRET 的检测可监测 Aha1 与 Hsp90 的结合，从而能够鉴定出几种调节 Aha1 对 Hsp90 活性影响的化合物。我们发现这些抑制剂之一可以消除 Aha1 诱导的 Hsp90 ATP 酶刺激，而在 Aha1 不存在的情况下不会显着影响 Hsp90 ATP 酶活性。 NMR 光谱显示，这种抑制性化合物与 Hsp90 的 N 端结构域结合，靠近其 ATP 结合位点，并与瞬时 Aha1 相互作用位点重叠。我们还注意到，这种抑制剂不会解离 Aha1-Hsp90 复合物，但会阻止与催化所需的 Hsp90 N 末端结构域的特异性相互作用。因此，该抑制剂影响了体内 Hsp90-Aha1 依赖性客户蛋白的激活和加工。我们的结论是，可以在不抑制整个 Hsp90 机制的情况下废除 Hsp90 的特定辅助伴侣功能。这个概念也可能适用于 Hsp90 的其他共伴侣。
The eukaryotic Hsp90 chaperone machinery comprises many co-chaperones and regulates the conformation of hundreds of cytosolic client proteins. Therefore, it is not surprising that the Hsp90 machinery has become an attractive therapeutic target for diseases such as cancer. The compounds used so far to target this machinery affect the entire Hsp90 system. However, it would be desirable to achieve a more selective targeting of Hsp90–co-chaperone complexes. To test this concept, in this-proof-of-principle study, we screened for modulators of the interaction between Hsp90 and its co-chaperone Aha1, which accelerates the ATPase activity of Hsp90. A FRET-based assay that monitored Aha1 binding to Hsp90 enabled identification of several chemical compounds modulating the effect of Aha1 on Hsp90 activity. We found that one of these inhibitors can abrogate the Aha1-induced ATPase stimulation of Hsp90 without significantly affecting Hsp90 ATPase activity in the absence of Aha1. NMR spectroscopy revealed that this inhibitory compound binds the N-terminal domain of Hsp90 close to its ATP-binding site and overlapping with a transient Aha1-interaction site. We also noted that this inhibitor does not dissociate the Aha1–Hsp90 complex but prevents the specific interaction with the N-terminal domain of Hsp90 required for catalysis. In consequence, the inhibitor affected the activation and processing of Hsp90–Aha1-dependent client proteins in vivo. We conclude that it is possible to abrogate a specific co-chaperone function of Hsp90 without inhibiting the entire Hsp90 machinery. This concept may also hold true for other co-chaperones of Hsp90.