THE P22 ERF PROTEIN AND HOST RECA PROVIDE ALTERNATIVE FUNCTIONS FOR TRANSDUCTIONAL SEGREGATION OF PLASMID-BORNE DUPLICATIONS

A tandem DNA duplication carried on a ColE1-derived plasmid segregates at high frequency upon generalized transduction by phage P22 HT. Tran sductional segregation of the plasmid-borne duplication can be promote d either by RecA or by the Erf function of P22, indicating that transd uctional segregation is a consequence of the recombination events that re-circularize the plasmid in the recipient cell. RecA-mediated and E rf-mediated transduction give similar frequencies of duplication segre gation and yield the same types of segregation products, indicating th at two distinct recombination machineries (RecA + RecBCD and Erf + Rec BCD) perform similar or identical recombination reactions on plasmid D NA substrates transduced by bacteriophage P22 HT.