To detect unwanted DNA edits than may cause harm, researchers conduct full genome sequencing, but it is a long and expensive process. To address this, the experts developed new methods to find off-target mutations in bacteria and human cells without the need for full genome sequencing. One of the devised methods entails insertion of base editors into bacteria and then tested for resistance to an antibiotic drug. The higher the frequency with which bacterial cells became resistant, the more active the base editor was in mutating the DNA in resistance genes.
The team used the methods to search for base-editing enzymes with better fidelity. This led them to a collection of enzymes that can convert cytosine to thymine without several off-target mutations. This is very important in using base editing as medicine. The team is planning to screen for base editors that will work well in plant cells.