Structural requirements for activity of Mind bomb1 in Notch signaling

IF 4.4 2区生物学 Q2 BIOCHEMISTRY & MOLECULAR BIOLOGY Structure Pub Date : 2024-08-08 DOI:10.1016/j.str.2024.07.011

引用次数: 0

Abstract

Mind bomb 1 (MIB1) is a RING E3 ligase that ubiquitinates Notch ligands, a necessary step for induction of Notch signaling. The structural basis for binding of the JAG1 ligand by the N-terminal region of MIB1 is known, yet how the ankyrin (ANK) and RING domains of MIB1 cooperate to catalyze ubiquitin transfer from E2∼Ub to Notch ligands remains unclear. Here, we show that the third RING domain and adjacent coiled coil region (ccRING3) drive MIB1 dimerization and that MIB1 ubiquitin transfer activity relies solely on ccRING3. We report X-ray crystal structures of a UbcH5B-ccRING3 complex and the ANK domain. Directly tethering the MIB1 N-terminal region to ccRING3 forms a minimal MIB1 protein sufficient to induce a Notch response in receiver cells and rescue mib knockout phenotypes in flies. Together, these studies define the functional elements of an E3 ligase needed for ligands to induce a Notch signaling response.

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心灵炸弹1在Notch信号转导中的活性结构要求

Mind bomb 1（MIB1）是一种 RING E3 连接酶，可泛素化 Notch 配体，这是诱导 Notch 信号转导的必要步骤。MIB1的N端区域与JAG1配体结合的结构基础是已知的，但MIB1的ankyrin（ANK）和RING结构域如何合作催化泛素从E2∼Ub转移到Notch配体上仍不清楚。在这里，我们发现第三个 RING 结构域和相邻的线圈区（ccRING3）驱动 MIB1 的二聚化，并且 MIB1 的泛素转移活性完全依赖于 ccRING3。我们报告了 UbcH5B-ccRING3 复合物和 ANK 结构域的 X 射线晶体结构。直接将 MIB1 N 端区域与 ccRING3 连接形成的最小 MIB1 蛋白足以诱导接收细胞中的 Notch 反应，并能挽救苍蝇的 mib 基因敲除表型。这些研究共同确定了配体诱导 Notch 信号反应所需的 E3 连接酶的功能要素。

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来源期刊

Structure 生物-生化与分子生物学

CiteScore

8.90

自引率

1.80%

发文量

155

审稿时长

3-8 weeks

期刊介绍： Structure aims to publish papers of exceptional interest in the field of structural biology. The journal strives to be essential reading for structural biologists, as well as biologists and biochemists that are interested in macromolecular structure and function. Structure strongly encourages the submission of manuscripts that present structural and molecular insights into biological function and mechanism. Other reports that address fundamental questions in structural biology, such as structure-based examinations of protein evolution, folding, and/or design, will also be considered. We will consider the application of any method, experimental or computational, at high or low resolution, to conduct structural investigations, as long as the method is appropriate for the biological, functional, and mechanistic question(s) being addressed. Likewise, reports describing single-molecule analysis of biological mechanisms are welcome. In general, the editors encourage submission of experimental structural studies that are enriched by an analysis of structure-activity relationships and will not consider studies that solely report structural information unless the structure or analysis is of exceptional and broad interest. Studies reporting only homology models, de novo models, or molecular dynamics simulations are also discouraged unless the models are informed by or validated by novel experimental data; rationalization of a large body of existing experimental evidence and making testable predictions based on a model or simulation is often not considered sufficient.