Abstract
In order to construct plasmids bearing inducible high-copy-number phenotype, the cloning plasmid pBR322 was modified as follows: a DNA fragment containing a strong synthetic promoter (P1), syntheticlac operator (O1), DNA sequence corresponding to the RNAI/RNAII region of the ColE1 replicon and the CAT gene transcription terminator was substituted for the 29 bpEcoRI/HindIII DNA fragment. Two types of plasmids were constructed in this way, differing in the orientation of the RNAI/RNAII fragment. Depending on the orientation these plasmids coded for RNA molecules representing either-RNAI or RNAII domains. It was found that when RNAII molecules were overproduced the plasmid copy number was about 4 times higher than that of pBR322 and only negligible change in the plasmid copy-number value was observed upon overproduction of RNAI molecules.
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Bachvarov, D., Jay, E. & Ivanov, I. Construction of aCColE1 plasmid bearing inducible high-copy-number phenotype. Folia Microbiol 35, 177–182 (1990). https://doi.org/10.1007/BF02820482
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DOI: https://doi.org/10.1007/BF02820482