Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories (MFPL), University of Vienna, Vienna BioCenter, Dr. Bohr-Gasse 9, 1030 Vienna, Austria.
Department of Crystallography, Max-Delbrück-Center for Molecular Medicine, Robert-Rössle-Strasse 10, 13125 Berlin, Germany; Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustrasse 6, 14195 Berlin, Germany.
Mol Cell. 2019 Apr 18;74(2):330-346.e11. doi: 10.1016/j.molcel.2019.01.035. Epub 2019 Mar 7.
The autophagy cargo receptor p62 facilitates the condensation of misfolded, ubiquitin-positive proteins and their degradation by autophagy, but the molecular mechanism of p62 signaling to the core autophagy machinery is unclear. Here, we show that disordered residues 326-380 of p62 directly interact with the C-terminal region (CTR) of FIP200. Crystal structure determination shows that the FIP200 CTR contains a dimeric globular domain that we designated the "Claw" for its shape. The interaction of p62 with FIP200 is mediated by a positively charged pocket in the Claw, enhanced by p62 phosphorylation, mutually exclusive with the binding of p62 to LC3B, and it promotes degradation of ubiquitinated cargo by autophagy. Furthermore, the recruitment of the FIP200 CTR slows the phase separation of ubiquitinated proteins by p62 in a reconstituted system. Our data provide the molecular basis for a crosstalk between cargo condensation and autophagosome formation.
自噬货物受体 p62 有助于凝聚错误折叠、泛素化阳性的蛋白质，并通过自噬将其降解，但 p62 向核心自噬机制发出信号的分子机制尚不清楚。在这里，我们表明 p62 的无序残基 326-380 直接与 FIP200 的 C 端区域（CTR）相互作用。晶体结构测定表明，FIP200 CTR 包含一个二聚球形结构域，因其形状我们将其命名为“爪”。p62 与 FIP200 的相互作用是通过“爪”中的正电荷口袋介导的，p62 磷酸化增强了这种相互作用，与 p62 与 LC3B 的结合相互排斥，并促进泛素化货物被自噬降解。此外，在重建系统中，FIP200 CTR 的募集会减缓 p62 凝聚泛素化蛋白质的相分离。我们的数据为货物凝聚和自噬体形成之间的串扰提供了分子基础。
