Recombination between short repeated sequences is more frequent in plasmids than in the chromosome of Bacillus subtilis

Abstract

We measured in Bacillus subtilis the recombination frequency between directly repeated 9 bp sequences flanking the transposon Tn5. Four different repeats were analyzed. They recombined with frequencies between 10(-7) and 10(-6) when they were carried on plasmids, and 150-1500 times less frequently when they were carried on the chromosome. We propose that this difference is due to the generation of single stranded DNA during plasmid replication.