6XKK

Cryo-EM structure of the NLRP1-CARD filament

Summary for 6XKK

• Entry DOI: 10.2210/pdb6xkk/pdb
• EMDB information: 22219 22220 22233
• Descriptor: NACHT, LRR and PYD domains-containing protein 1 (1 entity in total)
• Functional Keywords: filament, inflammasome, signaling, upa, card, fiind, nlrp1, immune system
• Biological source: Homo sapiens (Human)
• Total number of polymer chains: 44
• Total formula weight: 490107.86

Authors

Hollingsworth, L.R.,David, L.,Li, Y.,Sharif, H.,Fontana, P.,Fu, T.,Wu, H. (deposition date: 2020-06-26, release date: 2020-11-25, Last modification date: 2024-03-06)

Primary citation

Robert Hollingsworth, L.,David, L.,Li, Y.,Griswold, A.R.,Ruan, J.,Sharif, H.,Fontana, P.,Orth-He, E.L.,Fu, T.M.,Bachovchin, D.A.,Wu, H.
Mechanism of filament formation in UPA-promoted CARD8 and NLRP1 inflammasomes.
Nat Commun, 12:189-189, 2021

PubMed Abstract: NLRP1 and CARD8 are related cytosolic sensors that upon activation form supramolecular signalling complexes known as canonical inflammasomes, resulting in caspase-1 activation, cytokine maturation and/or pyroptotic cell death. NLRP1 and CARD8 use their C-terminal (CT) fragments containing a caspase recruitment domain (CARD) and the UPA (conserved in UNC5, PIDD, and ankyrins) subdomain for self-oligomerization, which in turn form the platform to recruit the inflammasome adaptor ASC (apoptosis-associated speck-like protein containing a CARD) or caspase-1, respectively. Here, we report cryo-EM structures of NLRP1-CT and CARD8-CT assemblies, in which the respective CARDs form central helical filaments that are promoted by oligomerized, but flexibly linked, UPAs surrounding the filaments. Through biochemical and cellular approaches, we demonstrate that the UPA itself reduces the threshold needed for NLRP1-CT and CARD8-CT filament formation and signalling. Structural analyses provide insights on the mode of ASC recruitment by NLRP1-CT and the contrasting direct recruitment of caspase-1 by CARD8-CT. We also discover that subunits in the central NLRP1 filament dimerize with additional exterior CARDs, which roughly doubles its thickness and is unique among all known CARD filaments. Finally, we engineer and determine the structure of an ASC-caspase-1 octamer, which suggests that ASC uses opposing surfaces for NLRP1, versus caspase-1, recruitment. Together these structures capture the architecture and specificity of the active NLRP1 and CARD8 inflammasomes in addition to key heteromeric CARD-CARD interactions governing inflammasome signalling.

PubMed: 33420033
DOI: 10.1038/s41467-020-20320-y

Experimental method

ELECTRON MICROSCOPY (3.72 Å)