FIG. 3.

Dose-response assays of ComD1 and ComD2. Exponentially growing S1 (ComD1) or S2 (ComD2) cells were incubated in the presence of increasing concentrations of CSP1 or CSP2 and assayed for β-galactosidase activity. At least five independent experiments were performed for each CSP concentration indicated. The data are presented as percent maximal activation plotted against the natural logarithm of [CSP] in nanomolar. Half-maximal activation of ComD1 was reached at 4.4 nM CSP1 or 600 nM CSP2, while half-maximal activation of ComD2 was reached at 14 nM CSP2 or 220 nM CSP1.