COPY-CHOICE ILLEGITIMATE DNA RECOMBINATION REVISITED

Nearly precise excision of a transposon related to Tn10 from an Escher ichia coli plasmid was used as a model to study illegitimate DNA recom bination between short direct repeats. The excision was stimulated 100 -1000 times by induction of plasmid single-stranded DNA synthesis and did not involve transfer of DNA from the parental to the progeny molec ule. We conclude that it occurred by copy-choice DNA recombination, an d propose that other events of recombination between short direct repe ats might be a result of the same process.