Ivanova Marina E, Lukoyanova Natalya, Malhotra Sony, Topf Maya, Trapani Joseph A, Voskoboinik Ilia, Saibil Helen R
Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet St, London WC1E 7HX, UK.
Imperial College London, Hammersmith Campus, Du Cane Road, London W12 0NN, UK.
Sci Adv. 2022 Feb 11;8(6):eabk3147. doi: 10.1126/sciadv.abk3147.
Perforin is a pore-forming protein that facilitates rapid killing of pathogen-infected or cancerous cells by the immune system. Perforin is released from cytotoxic lymphocytes, together with proapoptotic granzymes, to bind to a target cell membrane where it oligomerizes and forms pores. The pores allow granzyme entry, which rapidly triggers the apoptotic death of the target cell. Here, we present a 4-Å resolution cryo-electron microscopy structure of the perforin pore, revealing previously unidentified inter- and intramolecular interactions stabilizing the assembly. During pore formation, the helix-turn-helix motif moves away from the bend in the central β sheet to form an intermolecular contact. Cryo-electron tomography shows that prepores form on the membrane surface with minimal conformational changes. Our findings suggest the sequence of conformational changes underlying oligomerization and membrane insertion, and explain how several pathogenic mutations affect function.
穿孔素是一种形成孔道的蛋白质，可促进免疫系统快速杀死病原体感染的细胞或癌细胞。穿孔素与促凋亡颗粒酶一起从细胞毒性淋巴细胞中释放出来，与靶细胞膜结合，在那里它寡聚并形成孔道。这些孔道允许颗粒酶进入，从而迅速触发靶细胞的凋亡死亡。在这里，我们展示了穿孔素孔道的4埃分辨率冷冻电子显微镜结构，揭示了以前未发现的稳定组装的分子间和分子内相互作用。在孔道形成过程中，螺旋-转角-螺旋基序从中央β折叠的弯曲处移开，形成分子间接触。冷冻电子断层扫描显示，前孔在膜表面形成，构象变化最小。我们的研究结果表明了寡聚化和膜插入背后的构象变化顺序，并解释了几种致病突变如何影响功能。
