Structural insights into the recognition of phosphorylated FUNDC1 by LC3B in mitophagy.
Structural insights into the recognition of phosphorylated FUNDC1 by LC3B in mitophagy.
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线粒体自噬中 LC3B 识别磷酸化 FUNDC1 的结构见解
DOI：
10.1007/s13238-016-0328-8
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发表时间：
2017-01
期刊：
影响因子：
21.1
通讯作者：
Tang Y
中科院分区：
文献类型：
--
作者：
Lv M;Wang C;Li F;Peng J;Wen B;Gong Q;Shi Y;Tang Y
线粒体自噬是一个重要的细胞内过程，消除功能失调的线粒体，维持细胞内稳态。线粒体自噬受线粒体自噬受体的翻译后修饰调节。Fun14结构域蛋白1（FUNDC 1）是一种新的缺氧诱导的线粒体自噬受体，通过其LC3相互作用区（LIR）与微管相关蛋白轻链3 β（LC3B）相互作用。此外，FUNDC 1的磷酸化修饰影响其与LC3B的结合亲和力并调节选择性线粒体自噬。然而，这一调控机制的结构基础仍不清楚。在这里，我们提出了LC3B的晶体结构与FUNDC 1 LIR肽在Ser17（pS17）磷酸化，证明了LC3B的关键残基的磷酸化或去磷酸化的FUNDC 1的特异性识别。有趣的是，LC3B Lys49的侧链显著移位，并与FUNDC 1 pS17的磷酸基团形成氢键和静电相互作用。或者，FUNDC 1中磷酸化的Tyr 18（pY18）和Ser 13（pS13）分别显著阻碍它们与LC 3B的疏水口袋和Arg 10的相互作用。通过突变和等温滴定量热法（ITC）测定进一步验证结构观察。因此，我们的结构和生化结果揭示了一个工作模式的FUNDC 1的特异性识别LC3B和暗示，可逆的线粒体自噬受体的磷酸化修饰可能是一个开关选择性线粒体自噬。
Mitophagy is an essential intracellular process that eliminates dysfunctional mitochondria and maintains cellular homeostasis. Mitophagy is regulated by the post-translational modification of mitophagy receptors. Fun14 domain-containing protein 1 (FUNDC1) was reported to be a new receptor for hypoxia-induced mitophagy in mammalian cells and interact with microtubule-associated protein light chain 3 beta (LC3B) through its LC3 interaction region (LIR). Moreover, the phosphorylation modification of FUNDC1 affects its binding affinity for LC3B and regulates selective mitophagy. However, the structural basis of this regulation mechanism remains unclear. Here, we present the crystal structure of LC3B in complex with a FUNDC1 LIR peptide phosphorylated at Ser17 (pS17), demonstrating the key residues of LC3B for the specific recognition of the phosphorylated or dephosphorylated FUNDC1. Intriguingly, the side chain of LC3B Lys49 shifts remarkably and forms a hydrogen bond and electrostatic interaction with the phosphate group of FUNDC1 pS17. Alternatively, phosphorylated Tyr18 (pY18) and Ser13 (pS13) in FUNDC1 significantly obstruct their interaction with the hydrophobic pocket and Arg10 of LC3B, respectively. Structural observations are further validated by mutation and isothermal titration calorimetry (ITC) assays. Therefore, our structural and biochemical results reveal a working model for the specific recognition of FUNDC1 by LC3B and imply that the reversible phosphorylation modification of mitophagy receptors may be a switch for selective mitophagy.