Effects of recB, recC and recF mutations on Tn10 Transposition in Escherichia coli

Abstract

Both RecBC and RecF are involved in the regulation of Tn 10 in the genome of transposed Escherichia. coli cells. Depending on the conditions to which cells are exposed, either pathway could play the dominant role in the precise excision of the transposon. Previous studies have suggested that the RecF pathway plays a greater role in the precise excision of Tn 10 from the E. coli chromosome. In the current study, we attempted to understand the role of RecF in transposon excision by comparing the transposition frequencies between wild type, a recBC mutant and a recBCF mutant. Our results indicate that the RecBC excision pathway has a greater effect on Tn 10 transposition frequency. Varying MOIs and tetracycline concentrations also had an effect upon observed transposition frequencies. We propose that both RecBC and RecF excision pathways are activated in the recD mutant. It is possible that the RecBC-related DNA recombination machinery, which is required for Tn 10 excision DNA, is partially functional in the recD mutant; at the same time, the RecBCD inhibition on the RecF pathway has been lifted, allowing this pathway to be activated as well.