title: Identification of multifaceted binding modes for pyrin and ASC pyrin domains gives insights into pyrin inflammasome assembly.
abstract: Inflammasomes are macromolecular complexes that mediate inflammatory and cell death responses to pathogens and cellular stress signals. Dysregulated inflammasome activation is associated with autoinflammatory syndromes and several common diseases. During inflammasome assembly, oligomerized cytosolic pattern recognition receptors recruit procaspase-1 and procaspase-8 via the adaptor protein ASC. Inflammasome assembly is mediated by pyrin domains (PYDs) and caspase recruitment domains, which are protein interaction domains of the death fold superfamily. However, the molecular details of their interactions are poorly understood. We have studied the interaction between ASC and pyrin PYDs that mediates ASC recruitment to the pyrin inflammasome, which is implicated in the pathogenesis of familial Mediterranean fever. We demonstrate that both the ASC and pyrin PYDs have multifaceted binding modes, involving three sites on pyrin PYD and two sites on ASC PYD. Molecular docking of pyrin-ASC PYD complexes showed that pyrin PYD can simultaneously interact with up to three ASC PYDs. Furthermore, ASC PYD can self-associate and interact with pyrin, consistent with previous reports that pyrin promotes ASC clustering to form a proinflammatory complex. Finally, the effects of familial Mediterranean fever-associated mutations, R42W and A89T, on structural and functional properties of pyrin PYD were investigated. The R42W mutation had a significant effect on structure and increased stability. Although the R42W mutant exhibited reduced interaction with ASC, it also bound less to the pyrin B-box domain responsible for autoinhibition and hence may be constitutively active. Our data give new insights into the binding modes of PYDs and inflammasome architecture.
authors.affiliation: From the School of Chemistry and Molecular Biosciences and p.vajjhala@uq.edu.au.
authors.forename: Parimala R
authors.initials: PR
authors.lastname: Vajjhala
authors.affiliation: From the School of Chemistry and Molecular Biosciences and.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Kaiser
authors.affiliation: From the School of Chemistry and Molecular Biosciences and.
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Smith
authors.affiliation: From the School of Chemistry and Molecular Biosciences and.
authors.forename: Qi-Rui
authors.initials: QR
authors.lastname: Ong
authors.affiliation: From the School of Chemistry and Molecular Biosciences and.
authors.forename: Stephanie L
authors.initials: SL
authors.lastname: Soh
authors.affiliation: From the School of Chemistry and Molecular Biosciences and.
authors.forename: Katryn J
authors.initials: KJ
authors.lastname: Stacey
authors.affiliation: From the School of Chemistry and Molecular Biosciences and Centre for Advanced Imaging, The University of Queensland, Brisbane, Queensland 4072, Australia.
authors.forename: Justine M
authors.initials: JM
authors.lastname: Hill
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D053468:CARD Signaling Adaptor Proteins; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D058847:Inflammasomes / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016296:Mutagenesis; D019906:Nuclear Magnetic Resonance, Biomolecular; D011485:Protein Binding; D000071198:Pyrin; D017386:Sequence Homology, Amino Acid
chemical_list: D053468:CARD Signaling Adaptor Proteins; D003598:Cytoskeletal Proteins; D058847:Inflammasomes; C000604192:MEFV protein, human; C402202:PYCARD protein, human; D000071198:Pyrin
keywords: Death Domain; Familial Mediterranean Fever; Inflammasome; Inflammation; Innate Immunity; Mutagenesis; Pattern Recognition Receptor (PRR); Protein Complex; Protein-Protein Interaction; Pyrin