title: Cryo-EM Structure of Caspase-8 Tandem DED Filament Reveals Assembly and Regulation Mechanisms of the Death-Inducing Signaling Complex.
abstract: Caspase-8 activation can be triggered by death receptor-mediated formation of the death-inducing signaling complex (DISC) and by the inflammasome adaptor ASC. Caspase-8 assembles with FADD at the DISC and with ASC at the inflammasome through its tandem death effector domain (tDED), which is regulated by the tDED-containing cellular inhibitor cFLIP and the viral inhibitor MC159. Here we present the caspase-8 tDED filament structure determined by cryoelectron microscopy. Extensive assembly interfaces not predicted by the previously proposed linear DED chain model were uncovered, and were further confirmed by structure-based mutagenesis in filament formation in vitro and Fas-induced apoptosis and ASC-mediated caspase-8 recruitment in cells. Structurally, the two DEDs in caspase-8 use quasi-equivalent contacts to enable assembly. Using the tDED filament structure as a template, structural analyses reveal the interaction surfaces between FADD and caspase-8 and the distinct mechanisms of regulation by cFLIP and MC159 through comingling and capping, respectively.
authors.affiliation: Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA.
authors.forename: Tian-Min
authors.initials: TM
authors.lastname: Fu
authors.affiliation: Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA.
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA.
authors.forename: Alvin
authors.initials: A
authors.lastname: Lu
authors.affiliation: Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA.
authors.forename: Zongli
authors.initials: Z
authors.lastname: Li
authors.affiliation: School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, QLD 4072, Australia.
authors.forename: Parimala R
authors.initials: PR
authors.lastname: Vajjhala
authors.affiliation: Autoimmunity Branch, National Institute of Arthritis and Musculoskeletal and Skin Diseases, NIH, Bethesda, MD 20892, USA.
authors.forename: Anthony C
authors.initials: AC
authors.lastname: Cruz
authors.affiliation: Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA.
authors.forename: Devendra B
authors.initials: DB
authors.lastname: Srivastava
authors.affiliation: Department of Biochemistry, University of Washington, Seattle, WA 98195, USA.
authors.forename: Frank
authors.initials: F
authors.lastname: DiMaio
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Texas-Houston Medical School, Houston, TX 77030, USA.
authors.forename: Pawel A
authors.initials: PA
authors.lastname: Penczek
authors.affiliation: Autoimmunity Branch, National Institute of Arthritis and Musculoskeletal and Skin Diseases, NIH, Bethesda, MD 20892, USA.
authors.forename: Richard M
authors.initials: RM
authors.lastname: Siegel
authors.affiliation: School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, QLD 4072, Australia; Institute for Molecular Bioscience, University of Queensland, Brisbane, QLD 4072, Australia.
authors.forename: Katryn J
authors.initials: KJ
authors.lastname: Stacey
authors.affiliation: Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908, USA.
authors.forename: Edward H
authors.initials: EH
authors.lastname: Egelman
authors.affiliation: Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA. Electronic address: wu@crystal.harvard.edu.
authors.forename: Hao
authors.initials: H
authors.lastname: Wu
mesh_terms: D000595:Amino Acid Sequence; D017209:Apoptosis / Q000187:drug effects; D001665:Binding Sites; D053468:CARD Signaling Adaptor Proteins; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D053181:Caspase 8 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D020285:Cryoelectron Microscopy; D003598:Cytoskeletal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D053418:Death Domain Receptor Signaling Adaptor Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000071461:Death Effector Domain; D053200:Fas-Associated Death Domain Protein / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D019169:Jurkat Cells; D010957:Plasmids / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D000072756:Protein Conformation, alpha-Helical; D000072757:Protein Conformation, beta-Strand; D054730:Protein Interaction Domains and Motifs; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014162:Transfection; D014764:Viral Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D019014:fas Receptor / Q000494:pharmacology
chemical_list: D053468:CARD Signaling Adaptor Proteins; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D003598:Cytoskeletal Proteins; D053418:Death Domain Receptor Signaling Adaptor Proteins; C505533:FADD protein, human; C491901:FAS protein, human; D053200:Fas-Associated Death Domain Protein; C402202:PYCARD protein, human; D011993:Recombinant Fusion Proteins; D014764:Viral Proteins; D019014:fas Receptor; C509979:viral FLIP protein, Molluscum contagiosum virus; C505530:CASP8 protein, human; D053181:Caspase 8
keywords: DED; DISC; FADD; Fas; MC159; cFLIP; caspase-8; death domain; filament; vFLIP