Gasdermin-A3 pore formation propagates along variable pathways

Gasdermin-A3 pore formation propagates along diverse pathways. It begins with membrane attachment and oligomeric pre-assembly. Once inserted in the membrane, the oligomers re-assemble into various shapes and sizes, which open their lytic pores. Gasdermins are main effectors of pyroptosis, an inflammatory form of cell death. Released by proteolysis, the N-terminal gasdermin domain assembles large oligomers to punch lytic pores into the cell membrane. While the endpoint of this reaction, the fully formed pore, has been well characterized, the assembly and pore-forming mechanisms remain largely unknown. To resolve these mechanisms, we characterize mouse gasdermin-A3 by high-resolution time-lapse atomic force microscopy. We find that gasdermin-A3 oligomers assemble on the membrane surface where they remain attached and mobile. Once inserted into the membrane gasdermin-A3 grows variable oligomeric stoichiometries and shapes, each able to open transmembrane pores. Molecular dynamics simulations resolve how the membrane-inserted amphiphilic beta-hairpins and the structurally adapting hydrophilic head domains stabilize variable oligomeric conformations and open the pore. The results show that without a vertical collapse gasdermin pore formation propagates along a set of multiple parallel but connected reaction pathways to ensure a robust cellular response.

Automated summary

Gasdermin-A3 pore formation propagates along diverse pathways, and the assembly and pore-forming mechanisms have been characterized using high-resolution time-lapse atomic force microscopy. The results reveal the role of amphiphilic beta-hairpins and structurally adapting hydrophilic head domains in stabilizing variable oligomeric conformations and opening the pore.