Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK.
Department of Anesthesiology, Weill Cornell Medical College, 1300 York Ave., New York, NY 10065, USA.
Sci Adv. 2020 Jan 29;6(5):eaax8286. doi: 10.1126/sciadv.aax8286. eCollection 2020 Jan.
Perforin-2 (MPEG1) is thought to enable the killing of invading microbes engulfed by macrophages and other phagocytes, forming pores in their membranes. Loss of perforin-2 renders individual phagocytes and whole organisms significantly more susceptible to bacterial pathogens. Here, we reveal the mechanism of perforin-2 activation and activity using atomic structures of pre-pore and pore assemblies, high-speed atomic force microscopy, and functional assays. Perforin-2 forms a pre-pore assembly in which its pore-forming domain points in the opposite direction to its membrane-targeting domain. Acidification then triggers pore formation, via a 180° conformational change. This novel and unexpected mechanism prevents premature bactericidal attack and may have played a key role in the evolution of all perforin family proteins.
穿孔素-2（MPEG1）被认为能够使被巨噬细胞和其他吞噬细胞吞噬的入侵微生物死亡，在其膜上形成孔。穿孔素-2 的缺失使单个吞噬细胞和整个生物体更容易受到细菌病原体的侵害。在这里，我们使用预孔和孔组装的原子结构、高速原子力显微镜和功能测定揭示了穿孔素-2 的激活和活性机制。穿孔素-2 形成一个预孔组装，其中其孔形成结构域指向与其膜靶向结构域相反的方向。然后，酸化通过 180°构象变化触发孔形成。这种新颖和意外的机制可以防止过早的杀菌攻击，并且可能在所有穿孔素家族蛋白的进化中发挥了关键作用。
