Figure 4.

Kinetics of Mg²⁺-mediated capsule gene repression in GAS. Duplicate cultures of strain 003CAT were grown in THY to early exponential phase (arrow, Time 0), then one culture was supplemented with 15 mM MgCl₂ (filled symbols) and the other was not (open symbols). Growth curves for the two cultures were similar (Left). CAT activity, reflecting capsule gene expression, is shown for GAS cell extracts of the two cultures collected at the indicated time points (Right). Data points represent mean ± range for two independent experiments.