Fig. 2.

Assays for TrwC-mediated oriT-specific recombination. (a) Structure of the recombination cassette and the resulting product after recombination between the two oriT copies (black circles). Arrows point in the direction of transcription. Plac, lactose promoter. npt II, neomycin phosphotransferase gene conferring Km resistance. (b) DH5α (pRec2oriT-Cm) colonies transformed with pET3::trwAC and plated on CmAp X-Gal plates. Each blue sector originated from a single recombination event. (c) Assay for TrwC transfer into recipient cells carrying the recombination cassette. Helper nonmobilizable plasmids in the donor are indicated in brackets. Relaxases are shown as diamonds leading the DNA (wavy line) into recipient cells.