Cryo-EM Structure of Caspase-8 Tandem DED Filament Reveals Assembly and Regulation Mechanisms of the Death-Inducing Signaling Complex.Fu, T.M., Li, Y., Lu, A., Li, Z., Vajjhala, P.R., Cruz, A.C., Srivastava, D.B., DiMaio, F., Penczek, P.A., Siegel, R.M., Stacey, K.J., Egelman, E.H., Wu, H.
(2016) Mol Cell 64: 236-250
- PubMed: 27746017
- DOI: https://doi.org/10.1016/j.molcel.2016.09.009
- Primary Citation of Related Structures:
- PubMed 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.
Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908, USA.