Molecular Biology I, Center of Medical Biotechnology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany.
Centre for Structural Systems Biology, Leibniz-Institute of Virology and University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany.
EMBO J. 2023 Jul 17;42(14):e113110. doi: 10.15252/embj.2022113110. Epub 2023 Jun 2.
The AAA+-ATPase p97 (also called VCP or Cdc48) unfolds proteins and disassembles protein complexes in numerous cellular processes, but how substrate complexes are loaded onto p97 and disassembled is unclear. Here, we present cryo-EM structures of p97 in the process of disassembling a protein phosphatase-1 (PP1) complex by extracting an inhibitory subunit from PP1. We show that PP1 and its partners SDS22 and inhibitor-3 (I3) are loaded tightly onto p97, surprisingly via a direct contact of SDS22 with the p97 N-domain. Loading is assisted by the p37 adapter that bridges two adjacent p97 N-domains underneath the substrate complex. A stretch of I3 is threaded into the central channel of the spiral-shaped p97 hexamer, while other elements of I3 are still attached to PP1. Thus, our data show how p97 arranges a protein complex between the p97 N-domain and central channel, suggesting a hold-and-extract mechanism for p97-mediated disassembly.
AAA+-ATP 酶 p97（也称为 VCP 或 Cdc48）在众多细胞过程中展开蛋白质并拆解蛋白复合物，但底物复合物如何加载到 p97 上并被拆解尚不清楚。在这里，我们展示了 p97 在从蛋白磷酸酶 1（PP1）复合物中提取抑制亚基的过程中拆解 PP1 复合物的冷冻电镜结构。我们表明，PP1 及其伙伴 SDS22 和抑制剂-3（I3）通过 SDS22 与 p97 N 结构域的直接接触紧密加载到 p97 上，这令人惊讶。加载过程由连接底物复合物下方两个相邻 p97 N 结构域的 p37 接头辅助。I3 的一段被穿入螺旋形 p97 六聚体的中央通道，而 I3 的其他部分仍附着在 PP1 上。因此，我们的数据表明 p97 如何在 p97 N 结构域和中央通道之间安排蛋白复合物，这表明 p97 介导的拆解的“夹持-提取”机制。
