title: High-copy-number derivatives of the plasmid cloning vector pBR322.
abstract: A stable copy-number mutant of a pBR322-derived plasmid was isolated. The mutation was found to be a single G----T transversion located near the 3' end of a DNA segment coding for the regulatory RNA I. The resulting copy number for this plasmid is approx. 1000 per cell or 65% of total cellular DNA. Several cloning vectors have been constructed from this copy-number mutant and their practical application is discussed.
mesh_terms: D001483:Base Sequence; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D005784:Gene Amplification; D005822:Genetic Vectors; D009154:Mutation; D010957:Plasmids
chemical_list: D004269:DNA, Bacterial