The 26S proteasome is the essential compartmental protease in eukaryotic cells required for the ubiquitin-dependent clearance of damaged polypeptides and obsolete regulatory proteins. Recently, a combination of high-resolution structural, biochemical, and biophysical studies has provided crucial new insights into the mechanisms of this fascinating molecular machine. A multitude of new cryo-electron microscopy structures provided snapshots of the proteasome during ATP-hydrolysis-driven substrate translocation, and detailed biochemical studies revealed the timing of individual degradation steps, elucidating the mechanisms for substrate selection and the commitment to degradation through conformational transitions. It was uncovered how ubiquitin removal from substrates is mechanically coupled to degradation, and cryo-electron tomography studies gave a glimpse of active proteasomes inside the cell, their subcellular localization, and interactions with protein aggregates. Here, we summarize these advances in our mechanistic understanding of the proteasome, with a particular focus on how its structural features and conformational transitions enable the multi-step degradation process.

中文翻译：

---

从结构和构象动力学的角度了解26S蛋白酶体分子机器。

26S蛋白酶体是真核细胞中必不可少的间隔蛋白酶，是损伤多肽和过时调节蛋白的泛素依赖性清除所必需的。最近，高分辨率结构，生化和生物物理研究的结合为这种迷人的分子机器的机理提供了至关重要的新见解。众多新的低温电子显微镜结构为ATP水解驱动的底物移位过程中的蛋白酶体提供了快照，详细的生化研究揭示了单个降解步骤的时机，阐明了底物选择的机制以及通过构象转变对降解的承诺。已发现从底物上去除泛素如何与降解机械耦合，低温电子断层扫描研究以及细胞内活性蛋白酶体的概况，它们的亚细胞定位以及与蛋白质聚集体的相互作用。在这里，我们总结了对蛋白酶体的机械理解，并特别关注了其结构特征和构象转变如何促进多步降解过程。