Figure 3.

Determination of the NSP13 domain required for caspase-1 inhibition. (A) Diagrammatic representation of NSP13 deletion mutants. (B and C) HEK 293T cells were co-transfected with vectors expressing caspase-1 and pro-IL-1β plus either pEF1α-DEST or pEF1α-DEST expressing c-Myc-tagged NSP13 WT or mutants carrying deletions of zinc-binding domains (ZBD) (∆ZBD), the stalk domain (∆S), the 1B domain (∆1B), the two RecA-like domains, 1A (∆1A) and 2A (∆2A) and both 1A and 2A (∆1A/2A). After 24 h, (B) the concentrations of mature IL-1β secreted in culture supernatants were measured by ELISA, and (C) levels of caspase-1 and NSP13 (c-Myc) proteins and the cleavage of caspase-1 into its p20 subunit were determined by Western blotting. ELISA data are representative of three independent experiments. * p < 0.001 by unpaired two-tailed Student’s t-tests.