Journal: Sci Adv / Year: 2020 Title: Structure and mechanism of bactericidal mammalian perforin-2, an ancient agent of innate immunity. Authors: Tao Ni / Fang Jiao / Xiulian Yu / Saša Aden / Lucy Ginger / Sophie I Williams / Fangfang Bai / Vojtěch Pražák / Dimple Karia / Phillip Stansfeld / Peijun Zhang / George Munson / Gregor ...Authors: Tao Ni / Fang Jiao / Xiulian Yu / Saša Aden / Lucy Ginger / Sophie I Williams / Fangfang Bai / Vojtěch Pražák / Dimple Karia / Phillip Stansfeld / Peijun Zhang / George Munson / Gregor Anderluh / Simon Scheuring / Robert J C Gilbert / Abstract: 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 ...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.
A: Macrophage-expressed gene 1 protein B: Macrophage-expressed gene 1 protein C: Macrophage-expressed gene 1 protein D: Macrophage-expressed gene 1 protein E: Macrophage-expressed gene 1 protein F: Macrophage-expressed gene 1 protein G: Macrophage-expressed gene 1 protein H: Macrophage-expressed gene 1 protein