6n1i | pdb_00006n1i
Cryo-EM structure of NLRC4-CARD filament
Structural highlights
Disease[NLRC4_HUMAN] The disease is caused by mutations affecting the gene represented in this entry. The disease is caused by mutations affecting the gene represented in this entry. Function[NLRC4_HUMAN] Key component of inflammasomes that indirectly senses specific proteins from pathogenic bacteria and fungi and responds by assembling an inflammasome complex that promotes caspase-1 activation, cytokine production and macrophage pyroptosis (PubMed:15107016). The NLRC4 inflammasome is activated as part of the innate immune response to a range of intracellular bacteria (By similarity).[UniProtKB:Q3UP24][1] Publication Abstract from PubMedCanonical inflammasomes are cytosolic supramolecular complexes that activate caspase-1 upon sensing extrinsic microbial invasions and intrinsic sterile stress signals. During inflammasome assembly, adaptor proteins ASC and NLRC4 recruit caspase-1 through homotypic caspase recruitment domain (CARD) interactions, leading to caspase-1 dimerization and activation. Activated caspase-1 processes proinflammatory cytokines and Gasdermin D to induce cytokine maturation and pyroptotic cell death. Here, we present cryo-electron microscopy (cryo-EM) structures of NLRC4 CARD and ASC CARD filaments mediated by conserved three types of asymmetric interactions (types I, II, and III). We find that the CARDs of these two adaptor proteins share a similar assembly pattern, which matches that of the caspase-1 CARD filament whose structure we defined previously. These data indicate a unified mechanism for downstream caspase-1 recruitment through CARD-CARD interactions by both adaptors. Using structure modeling, we further show that full-length NLRC4 assembles via two separate symmetries at its CARD and its nucleotide-binding domain (NBD), respectively. Cryo-EM structures of ASC and NLRC4 CARD filaments reveal a unified mechanism of nucleation and activation of caspase-1.,Li Y, Fu TM, Lu A, Witt K, Ruan J, Shen C, Wu H Proc Natl Acad Sci U S A. 2018 Oct 2. pii: 1810524115. doi:, 10.1073/pnas.1810524115. PMID:30279182[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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