FIG 1.

Site-specific recombination by Int^SSV2. (A) Schematic representation of DNA fragments containing an attachment site for Int^SSV2. O, 7-bp overlap region; P and P′, the two arms of an attP site; A and A′, the two arms of an attA site. Lengths of the att fragments are indicated. (B) SDS-PAGE analysis of recombinant Int^SSV2. Recombinant Int^SSV2 was purified and subjected to 15% SDS-PAGE. The gel was stained with Coomassie brilliant blue R-250. Lane M shows markers with molecular masses in kilodaltons. (C) Integration by Int^SSV2. Int^SSV2 was incubated for 4 h at 65°C with ³²P-labeled A968 (11 nM) and unlabeled P730 (28 nM). The samples were treated with proteinase K and SDS and subjected to electrophoresis in a 1.5% agarose gel. The gel was exposed to X-ray film. The labeled substrate A968 and product L755 are indicated. For lane C, Int^SSV2 was omitted. (D) Effects of temperature, pH, and salt concentrations on the integration activity of Int^SSV2. (E) Effects of temperature, pH, and salt concentrations on the excision activity of Int^SSV2.