Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Frankfurt am Main, Germany.
Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA.
Sci Adv. 2024 Feb 9;10(6):eadj8027. doi: 10.1126/sciadv.adj8027. Epub 2024 Feb 7.
The covalent attachment of ubiquitin-like LC3 proteins (microtubule-associated proteins 1A/1B light chain 3) prepares the autophagic membrane for cargo recruitment. We resolve key steps in LC3 lipidation by combining molecular dynamics simulations and experiments in vitro and in cellulo. We show how the E3-like ligaseautophagy-related 12 (ATG12)-ATG5-ATG16L1 in complex with the E2-like conjugase ATG3 docks LC3 onto the membrane in three steps by (i) the phosphatidylinositol 3-phosphate effector protein WD repeat domain phosphoinositide-interacting protein 2 (WIPI2), (ii) helix α2 of ATG16L1, and (iii) a membrane-interacting surface of ATG3. Phosphatidylethanolamine (PE) lipids concentrate in a region around the thioester bond between ATG3 and LC3, highlighting residues with a possible role in the catalytic transfer of LC3 to PE, including two conserved histidines. In a near-complete pathway from the initial membrane recruitment to the LC3 lipidation reaction, the three-step targeting of the ATG12-ATG5-ATG16L1 machinery establishes a high level of regulatory control.
泛素样 LC3 蛋白（微管相关蛋白 1A/1B 轻链 3）的共价连接为货物募集准备了自噬膜。我们通过结合分子动力学模拟和体外及细胞内实验，解决了 LC3 脂质化的关键步骤。我们展示了 E3 样连接酶自噬相关蛋白 12（ATG12）-ATG5-ATG16L1 复合物如何通过三步将 LC3 连接到膜上：（i）磷脂酰肌醇 3-磷酸效应蛋白 WD 重复域磷酸肌醇相互作用蛋白 2（WIPI2），（ii）ATG16L1 的α2 螺旋，和（iii）ATG3 的膜相互作用表面。磷酸乙醇胺（PE）脂质在 ATG3 和 LC3 之间的硫酯键周围聚集，突出了可能在 LC3 向 PE 的催化转移中起作用的残基，包括两个保守的组氨酸。在从初始膜募集到 LC3 脂质化反应的近乎完整途径中，ATG12-ATG5-ATG16L1 机制的三步靶向建立了高度的调控控制。
