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Title | Mechanism of NAIP-NLRC4 inflammasome activation revealed by cryo-EM structure of unliganded NAIP5. |
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Journal, issue, pages | Nat Struct Mol Biol, Vol. 30, Issue 2, Page 159-166, Year 2023 |
Publish date | Jan 5, 2023 |
Authors | Bhaskar Paidimuddala / Jianhao Cao / Grady Nash / Qing Xie / Hao Wu / Liman Zhang / |
PubMed Abstract | The nucleotide-binding domain (NBD), leucine rich repeat (LRR) domain containing protein family (NLR family) apoptosis inhibitory proteins (NAIPs) are cytosolic receptors that play critical roles in ...The nucleotide-binding domain (NBD), leucine rich repeat (LRR) domain containing protein family (NLR family) apoptosis inhibitory proteins (NAIPs) are cytosolic receptors that play critical roles in the host defense against bacterial infection. NAIPs interact with conserved bacterial ligands and activate the NLR family caspase recruitment domain containing protein 4 (NLRC4) to initiate the NAIP-NLRC4 inflammasome pathway. Here we found the process of NAIP activation is completely different from NLRC4. Our cryo-EM structure of unliganded mouse NAIP5 adopts an unprecedented wide-open conformation, with the nucleating surface fully exposed and accessible to recruit inactive NLRC4. Upon ligand binding, the winged helix domain (WHD) of NAIP5 undergoes roughly 20° rotation to form a steric clash with the inactive NLRC4, which triggers the conformational change of NLRC4 from inactive to active state. We also show the rotation of WHD places the 17-18 loop at a position that directly bind the active NLRC4 and stabilize the NAIP5-NLRC4 complex. Overall, these data provide structural mechanisms of inactive NAIP5, the process of NAIP5 activation and NAIP-dependent NLRC4 activation. |
External links | Nat Struct Mol Biol / PubMed:36604500 / PubMed Central |
Methods | EM (single particle) |
Resolution | 3.3 - 3.6 Å |
Structure data | EMDB-24387, PDB-7rav: EMDB-24389: Cryo-EM structure of the unliganded form of NLR family apoptosis inhibitory protein 5 (NAIP5) with partial LRR domain |
Chemicals | ChemComp-ATP: |
Source |
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Keywords | IMMUNE SYSTEM / pre-liganded NAIP5 / inflammasome / innate immunity / host-pathogen interaction |