TABLE 3.

Orientation preference of IS903 insertions in pUB307 derivatives with a flipped oriT or oriV

Plasmida	Orientation of oriT/oriVb	Transfer frequencyc	Transposition frequencyc	Insertion specificityd	Orientation of insertionse
pUBF12 (native)	←/←	1.00	1.00	27/30 (90)	0:27
pUBF46	←/←	0.10	0.10	52/54 (96)	0:52
pUBF51	→/←	0.16	0.27	55/63 (87)	27:28
pRKF2	←/→	1.15	0.67	36/39 (92)	4:32
pRKF6	←/←	0.83	0.37	39/40 (98)	2:37

^aAll plasmids listed in this table are pUB307 derivatives containing the F traY-to-traL segment in the HindIII site in the same orientation (see Fig. 6). 

^bThe directions of vegetative DNA replication, oriV, and conjugal DNA transfer, oriT, are represented by arrows. The native orientation of oriV and oriT is that in pUBF12. 

^cThe transfer frequency of the control plasmid, pUBF12, is 3.51/donor cell in a 2-h mating, and transposition into this target occurs at 4.4 × 10⁻⁵/donor cell. All mating data were determined from at least three independent experiments. 

^dInsertion specificity is defined as the number of insertions into the F segment relative to the total number of insertions. Percentage equivalents are shown in parentheses. 

^eThe numbers preceding the colons indicate insertions in one orientation which were identified by primers OKD78 and OKD126. The numbers following the colons indicate insertions in the opposite orientation, identified by primers OKD79 and OKD126 (Fig. 5).