Recombination frequency in plasmid DNA containing direct repeats--predictive correlation with repeat and intervening sequence length.

In this study, a simple non-linear mathematical function is proposed to accurately predict recombination frequencies in bacterial plasmid DNA harbouring directly repeated sequences. The mathematical function, which was developed on the basis of published data on deletion-formation in multicopy plasmids containing direct-repeats (14-856 bp) and intervening sequences (0-3872 bp), also accounts for the strain genotype in terms of its recA function. A bootstrap resampling technique was used to estimate confidence intervals for the correlation parameters. More than 92% of the predicted values were found to be within a pre-established +/-5-fold interval of deviation from experimental data. The correlation does not only provide a way to predict, with good accuracy, the recombination frequency, but also opens the way to improve insight into these processes.