Abstract
Inflammatory caspases (caspases 1, 4, 5 and 11) are activated in response to microbial infection and danger signals. When activated, they cleave mouse and human gasdermin D (GSDMD) after Asp276 and Asp275, respectively, to generate an N-terminal cleavage product (GSDMD-NT) that triggers inflammatory death (pyroptosis) and release of inflammatory cytokines such as interleukin-1β. Cleavage removes the C-terminal fragment (GSDMD-CT), which is thought to fold back on GSDMD-NT to inhibit its activation. However, how GSDMD-NT causes cell death is unknown. Here we show that GSDMD-NT oligomerizes in membranes to form pores that are visible by electron microscopy. GSDMD-NT binds to phosphatidylinositol phosphates and phosphatidylserine (restricted to the cell membrane inner leaflet) and cardiolipin (present in the inner and outer leaflets of bacterial membranes). Mutation of four evolutionarily conserved basic residues blocks GSDMD-NT oligomerization, membrane binding, pore formation and pyroptosis. Because of its lipid-binding preferences, GSDMD-NT kills from within the cell, but does not harm neighbouring mammalian cells when it is released during pyroptosis. GSDMD-NT also kills cell-free bacteria in vitro and may have a direct bactericidal effect within the cytosol of host cells, but the importance of direct bacterial killing in controlling in vivo infection remains to be determined.
Publication types
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Research Support, N.I.H., Extramural
MeSH terms
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Amino Acid Sequence
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Animals
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Cardiolipins / metabolism
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Cell Line
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Cell Membrane / drug effects
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Cell Membrane / metabolism*
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Cell Membrane / ultrastructure
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Cell Membrane Permeability* / drug effects
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Conserved Sequence / genetics
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Escherichia coli / cytology
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Escherichia coli / drug effects
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Escherichia coli / metabolism
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Humans
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Inflammasomes / metabolism*
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Intracellular Signaling Peptides and Proteins
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Liposomes / chemistry
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Liposomes / metabolism
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Listeria monocytogenes / cytology
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Listeria monocytogenes / drug effects
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Listeria monocytogenes / metabolism
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Membrane Proteins / chemistry
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Membrane Proteins / genetics
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Membrane Proteins / metabolism
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Mice
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Mice, Inbred C57BL
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Microbial Viability / drug effects
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Microscopy, Electron
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Molecular Sequence Data
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Mutation
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Neoplasm Proteins / chemistry*
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Neoplasm Proteins / genetics
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Neoplasm Proteins / metabolism*
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Neoplasm Proteins / pharmacology
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Phosphate-Binding Proteins
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Phosphatidylinositol Phosphates / metabolism
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Phosphatidylserines / metabolism
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Porosity / drug effects
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Protein Multimerization / genetics
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Protein Structure, Tertiary / genetics
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Protein Transport
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Pyroptosis* / drug effects
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Pyroptosis* / genetics
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Staphylococcus aureus / cytology
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Staphylococcus aureus / drug effects
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Staphylococcus aureus / metabolism
Substances
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Cardiolipins
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GSDMA protein, human
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GSDMD protein, human
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Inflammasomes
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Intracellular Signaling Peptides and Proteins
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Liposomes
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Membrane Proteins
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Neoplasm Proteins
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Phosphate-Binding Proteins
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Phosphatidylinositol Phosphates
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Phosphatidylserines