Caspase-1 Engages Full-Length Gasdermin D through Two Distinct Interfaces That Mediate Caspase Recruitment and...

Area of Science:

• Biochemistry
• Molecular Biology
• Immunology

Background:

• Inflammatory caspases trigger pyroptosis, a cell death pathway, by cleaving gasdermin D (GSDMD).
• Cleavage site motifs were known, but their sufficiency for caspase interaction remained unclear.

Purpose of the Study:

• To elucidate the structural basis of caspase-1 recognition and cleavage of GSDMD.
• To investigate if cleavage sites are the sole determinants for caspase engagement.

Main Methods:

• Crystal structure determination of the human caspase-1 and murine GSDMD complex.
• Analysis of protein-protein interactions and binding interfaces.

Main Results:

• Identified a dual-interface engagement between caspase-1 and GSDMD.
• Revealed that caspase-1 binds GSDMD not only at the cleavage site linker but also via an exosite interaction with the GSDMD C-terminal domain.
• The GSDMD C-terminal domain acts as a caspase-recruitment module through this exosite.

Conclusions:

• Caspase-1 employs a dual-interface mechanism for GSDMD binding, involving both the active site and an exosite.
• This finding expands the understanding of caspase-substrate interactions beyond simple cleavage site recognition.
• The dual-interface engagement model may apply to other caspase substrates in physiological processes like pyroptosis.