A Rapid and Precise Mutation-Activated Fluorescence Reporter for Analyzing Acute Mutagenesis Frequency

Mutagenesis reporters are critical for quantifying genome stability. However, current methods rely on cell survival/death to report mutation, which takes weeks and prevents evaluation of acute or time-dependent changes. Existing methods also have other limitations, such as cell type restrictions. Using our discovery that mCherryFP fluorescence depends on residue Trp98, we replaced this codon with a stop codon to generate a mutation biosensor (termed CherryOFF), with a green fluorescence protein (GFP) as an internal control. We found that the red fluorescence of this biosensor is activated by a specific A/T-G/C nucleotide transition. Compared with the established hypoxanthine phosphoribosyl transferase assay, our reporter has similar or better ability to detect changes of mutation frequency induced by physical/chemical mutagens or manipulation of mutation-related genes. Furthermore, CherryOFF-GFP can report mutagenesis independently of cell-death events, can be adapted to many cell types, and can generate readouts within 1 day for the measurement of acute or time-dependent events.