Structure and assembly of a bacterial gasdermin pore

• Published in: Nature (London) Vol. 628; no. 8008; pp. 657 - 663
• Main Authors: Johnson, Alex G., Mayer, Megan L., Schaefer, Stefan L., McNamara-Bordewick, Nora K., Hummer, Gerhard, Kranzusch, Philip J.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 18.04.2024; Nature Publishing Group
• Subjects: 101/28; 631/326/1321; 631/535/1258/1259; 82/83; Animals; Apoptosis; Assemblies; Assembly; Cell death; Cell Membrane - metabolism; Cellular structure; Conformation; Cryoelectron Microscopy; Dynamic structural analysis; Electron microscopy; Gasdermins; Humanities and Social Sciences; Humans; Hydrophobicity; Lipids; Mammals - metabolism; Membranes; Mice; Microscopy; Molecular dynamics; multidisciplinary; Pore formation; Pores; Post-translation; Protein Subunits - metabolism; Proteins; Proteolysis; Pyroptosis; Science; Science (multidisciplinary); Sheaths; Streptococcus infections; Structural analysis; Toxicity
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/s41586-024-07216-3

In response to pathogen infection, gasdermin (GSDM) proteins form membrane pores that induce a host cell death process called pyroptosis 1 – 3 . Studies of human and mouse GSDM pores have revealed the functions and architectures of assemblies comprising 24 to 33 protomers 4 – 9 , but the mechanism and evolutionary origin of membrane targeting and GSDM pore formation remain unknown. Here we determine a structure of a bacterial GSDM (bGSDM) pore and define a conserved mechanism of pore assembly. Engineering a panel of bGSDMs for site-specific proteolytic activation, we demonstrate that diverse bGSDMs form distinct pore sizes that range from smaller mammalian-like assemblies to exceptionally large pores containing more than 50 protomers. We determine a cryo-electron microscopy structure of a Vitiosangium bGSDM in an active ‘slinky’-like oligomeric conformation and analyse bGSDM pores in a native lipid environment to create an atomic-level model of a full 52-mer bGSDM pore. Combining our structural analysis with molecular dynamics simulations and cellular assays, our results support a stepwise model of GSDM pore assembly and suggest that a covalently bound palmitoyl can leave a hydrophobic sheath and insert into the membrane before formation of the membrane-spanning β-strand regions. These results reveal the diversity of GSDM pores found in nature and explain the function of an ancient post-translational modification in enabling programmed host cell death. Cryo-electron microscopy and molecular dynamics studies of a Vitiosangium gasdermin pore reveal insights into the assembly of this large and diverse family of membrane pore-forming proteins.