Maitland Matthew E R, Onea Gabriel, Owens Dominic D G, Gonga-Cavé Brianna C, Wang Xu, Arrowsmith Cheryl H, Barsyte-Lovejoy Dalia, Lajoie Gilles A, Schild-Poulter Caroline
Robarts Research Institute, University of Western Ontario, London, ON, N6A 5B7, Canada.
Department of Biochemistry, University of Western Ontario, London, ON, N6G 2V4, Canada.
Commun Biol. 2024 Dec 19;7(1):1668. doi: 10.1038/s42003-024-07371-3.
The Pro/N-degron recognizing C-terminal to LisH (CTLH) complex is an E3 ligase of emerging interest in the developmental biology field and for targeted protein degradation (TPD) modalities. The human CTLH complex forms distinct supramolecular ring-shaped structures dependent on the multimerization of WDR26 or muskelin β-propeller proteins. Here, we find that, in HeLa cells, CTLH complex E3 ligase activity is dictated by an interplay between WDR26 and muskelin in tandem with muskelin autoregulation. Proteomic experiments revealed that complex-associated muskelin protein turnover is a major ubiquitin-mediated degradation event dependent on the CTLH complex in unstimulated HeLa cells. We observed that muskelin and WDR26 binding to the scaffold of the complex is interchangeable, indicative of the formation of separate WDR26 and muskelin complexes, which correlated with distinct proteomes in WDR26 and muskelin knockout cells. We found that mTOR inhibition-induced degradation of Pro/N-degron containing protein HMGCS1 is distinctly regulated by a muskelin-specific CTLH complex. Finally, we found that mTOR inhibition also activated muskelin degradation, likely as an autoregulatory feedback mechanism to regulate CTLH complex activity. Thus, rather than swapping substrate receptors, the CTLH E3 ligase complex controls substrate selectivity through the differential association of its β-propeller oligomeric subunits WDR26 and muskelin.
识别LisH（亮氨酸拉链样同源结构域）C末端的Pro/N-降解子的CTLH（C末端富含亮氨酸的Hect样结构域）复合物是一种E3连接酶，在发育生物学领域和靶向蛋白质降解（TPD）模式中越来越受到关注。人类CTLH复合物形成独特的超分子环状结构，这取决于WDR26或肌动蛋白β-螺旋桨蛋白的多聚化。在这里，我们发现，在HeLa细胞中，CTLH复合物的E3连接酶活性由WDR26和肌动蛋白之间的相互作用以及肌动蛋白的自动调节决定。蛋白质组学实验表明，在未受刺激的HeLa细胞中，与复合物相关的肌动蛋白周转是一种主要的泛素介导的降解事件，依赖于CTLH复合物。我们观察到，肌动蛋白和WDR26与复合物支架的结合是可互换的，这表明形成了单独的WDR26和肌动蛋白复合物，这与WDR26和肌动蛋白敲除细胞中的不同蛋白质组相关。我们发现，mTOR抑制诱导的含Pro/N-降解子的蛋白质HMGCS1的降解受肌动蛋白特异性CTLH复合物的明显调节。最后，我们发现mTOR抑制也激活了肌动蛋白的降解，这可能是一种自动调节反馈机制，用于调节CTLH复合物的活性。因此，CTLH E3连接酶复合物不是通过交换底物受体，而是通过其β-螺旋桨寡聚亚基WDR26和肌动蛋白的差异结合来控制底物选择性。
