FIG. 1.
Schematic representation of the integrated NBU1. NBU1 integrates site specifically into the 3′ end of a tRNALeu. The chromosomal DNA at the junctions of the integrated NBU1 is indicated by dotted lines and the ends of NBU1 are indicated by hatched boxes. The minimal region of NBU1 required for integration and excision contains the left end, including intN1 through two-thirds of the mobN1 gene as indicated by the arrow, and the right end from the ScaI site (22). Between PvuII and ScaI, just downstream of mobN1 and highlighted in gray, are four orfs of unknown functions that are not necessary for integration or excision. Below the map of ΩNBU1 (accession no. AF238307) is the region containing mobN1, oriT, and prmN1 cloned on the plasmid pPOM. This is the region that is nearly identical to the same region on NBU2 (accession no. AF251288).