DNA oligonucleotides and plasmids perform equally as donors for targeted gene conversion.

Site-specific gene modifications in cells are initiated by the introduction of exogenous DNA. We used a recently established cell assay to compare the ability of DNA donors to induce a single point mutation that converts a target gene encoding blue fluorescent protein (BFP) into expressing green fluorescent protein (GFP). In a chromosomal assay with cells stably expressing BFP, we showed that fluorescently labeled single-stranded oligonucleotides and a donor plasmid cotranscribing a red fluorescent protein provide similar efficiencies in triggering BFP–GFP conversions. In transient cotransfections, an isogenic donor plasmid comprising a nonfunctional GFP gene yielded a greater efficiency for the conversion of the BFP target gene than a nonisogenic donor, and all plasmid donors were superior to oligonucleotides.