Genetic requirements of phage lambda red-mediated gene replacement in Escherichia coli K-12

Recombination between short linear double-stranded DNA molecules and Escher ichia coli chromosomes bearing the red genes of bacteriophage lambda in pla ce of recBCD was tested in strains bearing: mutations in genes known to aff ect recombination in other cellular pathways. The linear DNA was a 4-kb fra gment containing the cat gene, with flanking lac sequences, released from a n infecting phage chromosome by restriction enzyme cleavage in the cell; fo rmation of Lac(-) chloramphenicol-resistant bacterial progeny was measured. Recombinant formation was found to be reduced in ruvAB and recQ strains. I n this genetic background, mutations in recF, recO, and recR had large effe cts on both cell viability and on recombination, In these cases, deletion o f the sulA gene improved viability and strain stability, without improving recombination ability, Expression of a gene(s) from the nin region of phage lambda partially complemented both the viability and recombination defects of the recF, recO, and recR mutants and the recombination defect of ruvC b ut not of ruvAB or recQ mutants.