SUMMARY: The two linear, integrated mini-circle copies of A3(2) were cloned in and their positions on the genetic map were determined. Mini-circle copy A is close to the , 20 kb upstream of the operon. Mini-circle copy B is close to the locus and is absent from J1501, which has suffered a chromosomal deletion including mini-circle copy B and possibly associated with the mutation. The mini-circle copies were not involved in any of the several previously identified physical interactions between the plasmid SCP1 and the chromosome. A new insertion sequence was identified close to the right end of mini-circle copy B in M145. The free mini-circle of , when inserted into an -deleted derivative of phage °C31, actively integrated this phage into the chromosomes of and at preferred and secondary sites. The resulting prophages were stably inherited and remained physically intact. No precise excision of prophages from lysogens carrying insertions at preferred or secondary integration sites was detected: instead, free phages were generated by imprecise excisions. These phages allowed the cloning of segments (> 3 kb in length) of the chromosomal DNA flanking preferred and secondary integration sites. Attempts to delete the preferred integration site by double homologous recombination with a clone carrying flanking DNA sequences and an antibiotic resistance gene were unsuccessful.


Article metrics loading...

Loading full text...

Full text loading...

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error