Extended Data Fig. 3: OspC3 modifies Arg314 in caspase-4 and the equivalent Arg310 in caspase-11.
From: Shigella evades pyroptosis by arginine ADP-riboxanation of caspase-11
a, EThcD-tandem mass spectrum of the Arg310-containing chymotryptic peptide from modified caspase-11-p30-C/A obtained by co-expression with OspC3 in bacteria. Fragmentation patterns generating the observed c/z and b/y ions are indicated along the peptide sequence. b, d, Caspase-4/11-p30-C/A or an Arg314/R310 mutant were expressed alone or together with OspC3 in 293T cells. Immunopurified caspase-4/11-p30 were analysed by ESI–MS to determine the total molecular mass.♦, a contamination ion that only appeared in the particular experiment. c, e, Caspase-4/11-p30-C/A or an R314/R310 mutant protein were reacted with OspC3 in the presence or absence of NAD+. The reactions were analysed by native/SDS-PAGE (c). Chymotrypsin-digested caspase-4/11-p30 proteins were analysed by mass spectrometry (e). Shown are the extracted ion chromatograms of the R314/R310-containing peptides. a, e, Mox, oxidized methionine. Data are representative of three (a, c, e) or two (b, d) independent experiments. For gel source data, see Supplementary Fig. 1.
