Figure 7. SilCR production and sensing by GAS and GGS.

(A) GAS can sense SilCR produced by GAS IB7 and GGS N3. Relative fluorescence was determined for the JS95pP₄-gfp “reporter strain” when grown with synthetic SilCR at the indicated concentrations (“Standard”, white bars) or in the presence of 10-fold diluted supernatants (“Jump start”) from IB7 (grey bars), N3 (black bars) and their derived mutants. α SilCR denotes addition of serum containing anti-SilCR polyclonal antibody [12], diluted 1∶40 into the reporter strain tube immediately before addition of the 10-fold diluted supernatants of the tested strains. The values shown are the mean ± the standard deviation results of at least two independent experiments. (B) GGS can sense SilCR produced by GAS IB7. Relative fluorescence of the N9pP₄-gfp “reporter strain” when grown with synthetic SilCR at the indicated concentrations (“Standard”, white bars) or in the presence of 3-fold diluted supernatants (“Jump start”) from IB7 WT and ΔsilAB, ΔsilCR mutants (grey bars).