The recA-dependent spontaneous degradation of proximal F merogenotes in Escherichia coli

Proximal F' elements of KLF-1 type are relatively stable in Escherichia coli recA recipients. In such merodiploids the transferability of F'-DNA and the plasmid determined fertility functions are expressed. When introduced into the wild type recA+ cells the F'-DNA is degraded and several classes of DNA molecules of molar mass about 66 Mg/mol and lower exist in the cell in 1-2 copies per bacterial chromosome. As was detected by complementation analysis, the chromosomal genes determining the host specificity for DNA (hsd) originally located on the F' element seem to be salvaged during the process of DNA degradation probably by recombination with the bacterial chromosome.