FIG. 1.

Plasmids used in the present study. Constructions are described in the text. ORFs (orf) and their directions of transcription are indicated by arrows. Restriction sites are shown for HinPI (H), EcoRI (E), ClaI (C), and SacI (S). Restriction sites no longer accessible are shown in brackets. R, ORF encoding restriction endonuclease; M, ORF encoding methylase; repA, replication protein. Thus far, no tentative function could be assigned to ORF4, -5, and -6, since they do not exhibit similarity to any functionally characterized gene product in the GenBank database.