Fig. 1. In vitro reconstitution of the enzymatic activity of CdnG.

a Schematic view of two operons encoding CdnG-Cap5 antiphage defense system. In addition to the genes encoding Cap5 and CdnG, a third gene encoding a conserved protein of unknown function might also be part of the operon (colored green). b UPLC analysis of the reaction mixtures carried out by AsCdnG. ApG is presumably the dephosphorylated product of the reaction intermediate pppApG. I, Inosine, which is presumably the dephosphorylated product of ITP resulting from deamination of ATP. Results are representative of three independent experiments. c UPLC analysis of the reaction mixtures carried out by LlCdnG. Results are representative of three independent experiments. d Proposed chemical steps of AsCdnG-catalyzed reaction to produce 3′,2′-cGAMP as the final product.