Institute of Precision Medicine, Peking University Shenzhen Hospital, Shenzhen, 518036, China.
Peking-Tsinghua Center for Life Sciences, Peking University, 100871, Beijing, China.
Nat Commun. 2024 May 6;15(1):3789. doi: 10.1038/s41467-024-48045-2.
The CUL3-RING E3 ubiquitin ligases (CRL3s) play an essential role in response to extracellular nutrition and stress stimuli. The ubiquitin ligase function of CRL3s is activated through dimerization. However, how and why such a dimeric assembly is required for its ligase activity remains elusive. Here, we report the cryo-EM structure of the dimeric CRL3 complex and reveal a conserved N-terminal motif in CUL3 that contributes to the dimerization assembly and the E3 ligase activity of CRL3. We show that deletion of the CUL3 N-terminal motif impairs dimeric assembly and the E3 ligase activity of both CRL3 and several other CRL3s. In addition, we found that the dynamics of dimeric assembly of CRL3 generates a variable ubiquitination zone, potentially facilitating substrate recognition and ubiquitination. These findings demonstrate that a CUL3 N-terminal motif participates in the assembly process and provide insights into the assembly and activation of CRL3s.
CUL3-RING E3 泛素连接酶（CRL3s）在响应细胞外营养和应激刺激方面发挥着重要作用。CRL3s 的泛素连接酶功能通过二聚化激活。然而，这种二聚体组装如何以及为何需要其连接酶活性仍然难以捉摸。在这里，我们报告了二聚体 CRL3 复合物的冷冻电镜结构，并揭示了 CUL3 中一个保守的 N 端基序，该基序有助于 CRL3 的二聚体组装和 E3 连接酶活性。我们表明，删除 CUL3 N 端基序会损害二聚体组装和 CRL3 及其他几种 CRL3 的 E3 连接酶活性。此外，我们发现 CRL3 二聚体组装的动力学产生了一个可变的泛素化区域，可能有助于底物识别和泛素化。这些发现表明，CUL3 的 N 端基序参与了组装过程，并为 CRL3 的组装和激活提供了深入了解。
