ISOLATION AND CHARACTERIZATION OF LAMBDA-TRA TRANSDUCING PHAGES FROM EDFL223 (FLAC-TRAB-ED-LAMBDA-4)

A series of λ transducing phages carrying transfer (tra) genes have been isolated from an abnormal lysogen where the λ prophage was inserted into the traB gene of Flac. These have been characterised genetically by complementation analysis with Flac tra point mutants, and by studying tra gene expression during λ repression. Taken together, the phages cover the entire transfer region except for oriT and traI. The tra genes were expressed from the λ promoter pl in all cases, as well as from the tra promoters when these were present. Evidence was obtained suggesting that in F there is a separate promoter for traI. DNA isolated from the λtra phages was characterised physico-chemically by determination of the endonuclease R.EcoRI fragmentation pattern, and by electron microscope heteroduplex analysis. These data were used to construct an improved physical map of the transfer region. © 1978.