Fig. 5: A conserved toxin inhibition mechanism in Gram-positive bacteria.
a His-tag pull down assay. A His-SUMO tag was co-expressed on the N-terminus of YezG (His-YezG) and YeeF508-555 (His-YeeF508-555) to chelate with the nickel beads. All the proteins were purified from E. Coli. Proteins are indicated by Coomassie blue staining. The experiments were performed twice with similar results. b In vitro nuclease activity of YeeF fragments. The gel was stained with ethidium bromide and visualized under UV light. The experiments were performed three times with similar results. c Cartoon representation of the molecular model for the mechanism of EsaD inhibition by EsaG. The nuclease activity of EsaD is inhibited upon its synthesis by insertion of EsaG monomer into the core structure of EsaD, leading to the disorder of the ββα-metal finger. The EsaD-EsaG complex may form tetramer when accumulated in the bacteria. EsaG proteins are removed from the complex and left behind when EsaD proteins are translocated through the T7SS. This model shows the ribosome (a), the newly synthetized EsaD (b), EsaG (c), EsaD-EsaG heterodimer (d), EsaD-EsaG heterotetramer (e) and the T7SS (f).
