FIG. 5.

Effects of mutations in and immediately downstream of the DnaA box on the ability of the ori plasmid to be activated for replication by RepA provided in trans. Copy numbers were determined by assaying the CAT activity of E. coli strain JP3438 carrying the ori plasmids, in the absence of IPTG. The values shown are the average of at least six independent determinations. NR, ori plasmid unable to replicate without the induction of the pAM34 replicon; H, copy number too high to be determined accurately; the thin line, region deleted; □, DnaA box; ▿, 5- or 10-bp insertion; ▹, transcription terminator.