FIG. 3.

Effects of substitutions of CIS and ori on the relative copy numbers of the IncB replicons of pMU1598 and pMU1599. The copy number was determined by assaying the CAT activity of E. coli JP3438 carrying pMU1598 or its derivatives in the absence of IPTG and is expressed relative to the value obtained for pMU1598. The values shown are the averages of at least six independent determinations. trpA ter is a 28-bp trpA transcription terminator flanked by linker sequences so that the overall length of 5′CIS is maintained. ND, not done; NR, plasmid unable to initiate replication from the IncB replicon.