[Effectiveness of plasmid RP4 mobilization of the bacterial chromosome in Escherichia coli strains lysogenic for phages Mu and lambda].

The effect of phage lambda on mobilization of Escherichia coli chromosome mediated by the Mu phage and RP4 plasmid has been studied. The efficiency of bacterial chromosome mobilization is an order of magnitude lower than that in the control strain, monolysogenic for phage Mu provided a termoinducible prophage lambda is located separately from Mu. This efficiency is an order of magnitude higher in comparison with the control strain in case prophage is incorporated in the Mu-lambda-Mu structure and does not inhibit Mu phage development. Thus the effect of bacteriophage Mu on mobilization of E. coli chromosome determined by this phage and RP4 plasmid is shown to be dependent on localization of prophage lambda, as well as on functioning of certain prophage genes. A possibility of replication of Mu genomes from the ori site of prophage lambda incorporated into the Mu-lambda-Mu structure is discussed. This replication is presumed to have a stimulating effect on the Mu-induced mobilization of the bacterial chromosome.