Caspase-1 and IL-1β Processing in a Teleost Fish
Figure 5
Cleavage of in vitro translated bass proIL-1β and proIL1β[D100A] by sea bass caspase-1.
The same volume of in vitro synthesized proIL1β and proIL1β[D100A] were used and loaded on the gel. Fragments 1, 2 and 3 are labeled. Putative mature in vitro synthesized sea bass IL1β (MS101-Q261) has been loaded as control. Numbers on the left indicate the mass of the molecular weight markers in kDa. The double bands corresponding to the highest molecular weight form (fragment 1) suggested cleavage at the C-terminal end of proIL-1β. This interpretation was supported by N-terminal sequencing of fragment 1′ (Fig. S3B), which revealed that this fragment has the N-terminal sequence of proIL-1β (M1ESEMKC). Furthermore, mutation of D252 results in a proIL-1β protein that no longer yields fragment 1 upon incubation with caspase-1 (Fig S3C).