An Assay for the Seeding of Homotypic Pyrin Domain Filament Transitions.

Pattern recognition receptors of innate immune cells allow the recognition of invariant microbial structures. The nucleotide-binding oligomerization domain-like receptors (NLRs) comprise 22 members, divided into 3 subfamilies. Homotypic pyrin domain (PYD) interactions were shown to mediate the interaction of inflammasome forming NLRPs with the adaptor protein ASC, bridging the interaction to caspase-1 and resulting in caspase-1-induced cytokine maturation and pyroptotic cell death. Here we describe a NLRP3PYD-mediated ASC polymerization assay that reconstitutes the transition from the NLRP3PYD nucleation seed to ASC adaptor filament elongation with recombinant proteins.