Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley CA 94720, USA.
Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley CA 94720, USA; Howard Hughes Medical Institute, University of California at Berkeley, Berkeley CA 94720, USA; Quantitative Biosciences Institute, QB3, University of California at Berkeley, Berkeley CA 94720, USA.
Mol Cell. 2022 Feb 3;82(3):585-597.e11. doi: 10.1016/j.molcel.2022.01.004.
Cullin-RING E3 ligases (CRLs) are essential ubiquitylation enzymes that combine a catalytic core built around cullin scaffolds with ∼300 exchangeable substrate adaptors. To ensure robust signal transduction, cells must constantly form new CRLs by pairing substrate-bound adaptors with their cullins, but how this occurs at the right time and place is still poorly understood. Here, we show that formation of individual CRL complexes is a tightly regulated process. Using CUL3 as a model, we found that its co-adaptor PEF1-ALG2 initiates CRL3 formation by releasing KLHL12 from an assembly inhibitor at the endoplasmic reticulum, before co-adaptor monoubiquitylation stabilizes the enzyme for substrate modification. As the co-adaptor also helps recruit substrates, its role in CRL assembly couples target recognition to ubiquitylation. We propose that regulators dedicated to specific CRLs, such as assembly inhibitors or co-adaptors, cooperate with target-agnostic adaptor exchange mechanisms to establish E3 ligase complexes that control metazoan development.
Cullin-RING E3 连接酶（CRLs）是一种必需的泛素化酶，它将围绕 cullin 支架构建的催化核心与约 300 个可交换的底物衔接子结合在一起。为了确保稳健的信号转导，细胞必须通过将结合底物的衔接子与它们的 cullin 配对，不断形成新的 CRL，但这在何时以及何地发生仍知之甚少。在这里，我们表明，单个 CRL 复合物的形成是一个受到严格调控的过程。我们以 CUL3 作为模型，发现其共同衔接子 PEF1-ALG2 通过在 ER 上将 KLHL12 从组装抑制剂中释放出来，从而启动 CRL3 的形成，然后共同衔接子单泛素化稳定酶以进行底物修饰。由于共同衔接子还有助于招募底物，因此其在 CRL 组装中的作用将靶标识别与泛素化偶联在一起。我们提出，专门针对特定 CRL 的调节剂，如组装抑制剂或共同衔接子，与目标不可知的衔接子交换机制合作，以建立控制后生动物发育的 E3 连接酶复合物。
