Dual fluorescent protein-based bioassay system for the detection of genotoxic chemical substances in Saccharomyces cerevisiae.

A new reporter system has been developed for quantifying the activity of potentially DNA-damaging substances in the yeast Saccharomyces cerevisiae. The system relies on two different reporter genes, yEGFP and DsRed-Express2, to screen for DNA-damaging chemicals. The yEGFP gene is fused to the test promoter of RNR2, whose measurable signal has a dose-dependent relationship with DNA damage. The gene encoding DsRed-Express2 is fused to a constitutive promoter of GPD, providing an internal control for normalizing cell numbers in the assay. The dual fluorescent protein assay system is performed by sequentially measuring the yEGFP and DsRed-Express2 fluorescent intensity of the same sample, with the results expressed as the ratio of yEGFP to DsRed-Express2 intensity (yEGFP/DsRed-Express2). The yeast fluorescent protein reporter assay was performed in 96-well microtiter plates in the presence of different concentrations of test substances, which were then characterized. The assay was very efficient, high-throughput, and amenable to full automation. Here, we demonstrate that this system can be used as a biosensor to assess the genotoxic potential of drugs and other chemical substances.