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Publication Abstract from PubMed

Several interleukin-1 (IL-1) family members, including IL-1beta and IL-18, require processing by inflammasome-associated caspases to unleash their activities. Here, we unveil, by cryoelectron microscopy (cryo-EM), two major conformations of the complex between caspase-1 and pro-IL-18. One conformation is similar to the complex of caspase-4 and pro-IL-18, with interactions at both the active site and an exosite (closed conformation), and the other only contains interactions at the active site (open conformation). Thus, pro-IL-18 recruitment and processing by caspase-1 is less dependent on the exosite than the active site, unlike caspase-4. Structure determination by nuclear magnetic resonance uncovers a compact fold of apo pro-IL-18, which is similar to caspase-1-bound pro-IL-18 but distinct from cleaved IL-18. Binding sites for IL-18 receptor and IL-18 binding protein are only formed upon conformational changes after pro-IL-18 cleavage. These studies show how pro-IL-18 is selected as a caspase-1 substrate, and why cleavage is necessary for its inflammatory activity.

Structural transitions enable interleukin-18 maturation and signaling.,Dong Y, Bonin JP, Devant P, Liang Z, Sever AIM, Mintseris J, Aramini JM, Du G, Gygi SP, Kagan JC, Kay LE, Wu H Immunity. 2024 May 8:S1074-7613(24)00220-6. doi: 10.1016/j.immuni.2024.04.015. PMID:38733997^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.