1. Effect of CSP18 on induction of competence and expression of cipB, sigX, comGA, and comEC during growth in TSB. (A) During growth of S. mutans UA159 in the presence (●) or absence (○) of CSP, transformation efficiency (solid line) and OD600 (broken line) were determined at the times indicated.
Effect of CSP18 on induction of competence and expression of cipB, sigX, comGA, and comEC during growth in TSB. (A) During growth of S. mutans UA159 in the presence (●) or absence (○) of CSP, transformation efficiency (solid line) and OD600 (broken line) were determined at the times indicated. Exposure to pVA838 was for 20 min and was followed by further incubation with DNase I for 40 min before plating. Arrows show the times of sample harvesting for microarray analysis. (B) Luciferase reporters were used in parallel cultures to measure the effect of CSP on the expression of cipB (nlmC, SMU.1914) (triangles) and sigX (squares). The strains were grown in the presence of 50 nM CSP (filled symbols) or without CSP (empty symbols). CSP was added at t = 0. Relative light units (RLU) and OD600 were measured in a 96-well plate with a multidetection microplate reader (SynergyHT; BioTek). Expression levels are relative to the highest value of each reporter (100%). Error bars indicate standard deviations of triplicate assays. (C to E) Relative expression of selected early responsive gene cipB (C) and late responsive genes comGA and comEC (D and E). Real-time PCR data were normalized to the expression values of the respective genes in the WT strain at 5 min without CSP. Mean values and standard errors for three replicates at 5, 10, and 100 min without CSP (red bars) and with CSP (blue bars) are shown.
R. Khan et al. mSystems 2016; doi: /mSystems