title: Amplification of bacterial plasmids without blocking protein biosynthesis.
abstract: The effect of amino acids (presence or absence from the growth media) and metal ions on the replication of Escherichia coli plasmids in rel A+ strains was studied. It was found that: (i) The absence of one amino acid from the growth media had no effect on the plasmid copy number in prototrophic E. coli strains: (ii) The presence of only one amino acid in artificial media free of amino acids had a negligible effect on the plasmid copy number for the amino acids Ala, Arg, Glu, His, Leu, Phe, Thr, Trp, and Tyr: (iii) The combination of Met and Thr caused a rise in pBR322 plasmid copy number up to 90-100 plasmid copies per cell: (iv) The Fe3+ concentration had an amplification effect on E. coli plasmids. The pBR322 plasmid copy number for media free of amino acids and supplemented with 0.2-0.4 mM FeCl3 was 60-80 plasmid copies per cell: (v) The combination of Fe3+ with certain amino acids (Ala, Arg, Glu, Leu, Thr, and Trp) leads to a dramatic increase in the plasmid copy number reaching 180-270 plasmid copies per cell for the plasmid pBR322 and 20-24 for the plasmid pR100.
authors.affiliation: Institute of Molecular Biology, Bulgarian Academy of Sciences, Sofia.
authors.forename: I
authors.initials: I
authors.lastname: Angelov
authors.forename: I
authors.initials: I
authors.lastname: Ivanov
mesh_terms: D000596:Amino Acids / Q000494:pharmacology; D003470:Culture Media; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development; D005784:Gene Amplification / Q000187:drug effects; D007501:Iron / Q000494:pharmacology; D008969:Molecular Sequence Data; D010957:Plasmids; D014176:Protein Biosynthesis
chemical_list: D000596:Amino Acids; D003470:Culture Media; D007501:Iron