FIG 7.
Enhancement of CSP-mediated comX expression by carbohydrates requires their cognate PTS transporter(s). Cells of S. mutans UA159 (or the gtfBC mutant in the case of sucrose) as well as a fruI fruCD levD (A), treB (B), malT (C), or gtfBC scrA (D) derivative of UA159 containing PcomX-lacZ were grown in TVB supplemented with 20 mM glucose (glc) or 17.5 mM glucose and 2.5 mM inducing carbohydrate. The inducing carbohydrates were fructose (fru) (A), trehalose (tre) (B), maltose (mal) (C), and sucrose (suc) (D). Cultures were grown to an OD600 of 0.1, treated with 1 μM CSP, and incubated for an additional 2 h. LacZ assays were performed to determine the expression of comX. Data represent the mean of three independent replicates, with error bars indicating the standard deviation. *, P < 0.05, and ***, P < 0.005, by the Student t test.