华盛顿大学郑宁小组宣布他们的研究显示，CSN5i-3是COP9信号体的正位分子胶抑制剂。2026年2月11日，国际知名学术期刊《自然》发表了这一成果。

在这里，课题组人员展示了分子胶机制意外地赋予CSN5i-3底物依赖性效力，CSN5i-3是COP9信号体（CSN）的正位抑制剂。该研究组首先证实，CSN5i-3通过占据其催化亚基CSN5的活性位点，并直接与同肽键底物竞争，抑制了催化cullin-RING泛素连接酶NEDD8 （N8）解偶联的CSN。值得注意的是，正位抑制剂仅以微摩尔亲和力结合游离CSN，但在阻断其去甲肼酶活性方面达到纳摩尔效力。酶-底物-抑制剂复合物的低温电镜结构显示，活性位点参与的CSN5i-3阻断了底物的同肽链，同时扩展了CSN5的N8结合外源位点，作为分子胶来巩固N8-CSN5的相互作用。这种三分子CSN5i-3–N8–CSN5组装体的协同性反过来将CSN5i-3隔离在其结合位点，尽管对游离酶的亲和力较低，但仍赋予了正位抑制剂高效力。总之，他们的发现强调了分子胶对单个靶蛋白的适度亲和力要求，并建立了正位分子胶抑制剂作为一类新的底物依赖性酶拮抗剂。

据了解，正位抑制剂阻断酶活性位点并阻止底物的结合。通过底物依赖性来增强它们的特异性似乎不太可能，因为它们的机制取决于直接竞争而不是选择性识别。

附：英文原文

Title: CSN5i-3 is an orthosteric molecular glue inhibitor of COP9 signalosome

Author: Shi, Huigang, Wang, Xiaorong, Yu, Clinton, Mao, Haibin, Jiao, Fenglong, Braitbard, Merav, Shor, Ben, Zhang, Zhongsheng, Hinds, Thomas R., Cao, Shiyun, Fan, Erkang, Schneidman-Duhovny, Dina, Huang, Lan, Zheng, Ning

Issue&Volume: 2026-02-11

Abstract: Orthosteric inhibitors block enzyme active sites and prevent substrates from binding1. Enhancing their specificity through substrate dependence seems inherently unlikely, as their mechanism hinges on direct competition rather than selective recognition. Here we show that a molecular glue mechanism unexpectedly imparts substrate-dependent potency to CSN5i-3, an orthosteric inhibitor of the COP9 signalosome (CSN). We first confirm that CSN5i-3 inhibits CSN, which catalyses NEDD8 (N8) deconjugation from the cullin-RING ubiquitin ligases, by occupying the active site of its catalytic subunit, CSN5, and directly competing with the iso-peptide bond substrate. Notably, the orthosteric inhibitor binds free CSN with only micromolar affinity, yet achieves nanomolar potency in blocking its deneddylase activity. Cryogenic electron microscopy structures of the enzyme–substrate–inhibitor complex reveal that active site-engaged CSN5i-3 occludes the substrate iso-peptide linkage while simultaneously extending an N8-binding exosite of CSN5, acting as a molecular glue to cement the N8–CSN5 interaction. The cooperativity of this trimolecular CSN5i-3–N8–CSN5 assembly, in turn, sequesters CSN5i-3 at its binding site, conferring high potency to the orthosteric inhibitor despite its low affinity for the free enzyme. Together, our findings highlight the modest affinity requirements of molecule glues for individual target proteins and establish orthosteric molecular glue inhibitors as a new class of substrate-dependent enzyme antagonists.

DOI: 10.1038/s41586-026-10129-y

Source: https://www.nature.com/articles/s41586-026-10129-y