Abstract
Streptococcus faecalis DT-11 harbors the 6.0-megadalton plasmid pAMalpha1, which determines resistance to tetracycline (TC). When this strain is grown in the presence of TC for a number of generations, a reversible gene amplification occurs, generating tandem repeats of a 2.65-megadalton segment of the plasmid. On the basis of heteroduplex studies between various forms of pAMalpha1 and fragments generated by the Escherichia coli restriction endonuclease EcoRI, we have obtained direct evidence for the presence of a small sequence designated RS1 (for recombination sequence) located on both sides of the TC resistance determinant. Corresponding points on the two sequences are separated by 2.65 megadaltons of deoxyribonucleic acid. The two RS1 sequences have the same polarity and are of a size corresponding to about 380 nucleotide base pairs. The data presented serve as strong support for amplification models that are based on recombinational events involving the RS1 sequences.
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- Clewell D. B., Helinski D. R. Properties of a supercoiled deoxyribonucleic acid-protein relaxation complex and strand specificity of the relaxation event. Biochemistry. 1970 Oct 27;9(22):4428–4440. doi: 10.1021/bi00824a026. [DOI] [PubMed] [Google Scholar]
- Clewell D. B. Nature of Col E 1 plasmid replication in Escherichia coli in the presence of the chloramphenicol. J Bacteriol. 1972 May;110(2):667–676. doi: 10.1128/jb.110.2.667-676.1972. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Clewell D. B., Yagi Y., Bauer B. Plasmid-determined tetracycline resistance in Streptococcus faecalis: evidence for gene amplification during growth in presence of tetracycline. Proc Natl Acad Sci U S A. 1975 May;72(5):1720–1724. doi: 10.1073/pnas.72.5.1720. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Clewell D. B., Yagi Y., Dunny G. M., Schultz S. K. Characterization of three plasmid deoxyribonucleic acid molecules in a strain of Streptococcus faecalis: identification of a plasmid determining erythromycin resistance. J Bacteriol. 1974 Jan;117(1):283–289. doi: 10.1128/jb.117.1.283-289.1974. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Dunny G. M., Clewell D. B. Transmissible toxin (hemolysin) plasmid in Streptococcus faecalis and its mobilization of a noninfectious drug resistance plasmid. J Bacteriol. 1975 Nov;124(2):784–790. doi: 10.1128/jb.124.2.784-790.1975. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hu S., Otsubo E., Davidson N., Saedler H. Electron microscope heteroduplex studies of sequence relations among bacterial plasmids: identification and mapping of the insertion sequences IS1 and IS2 in F and R plasmids. J Bacteriol. 1975 May;122(2):764–775. doi: 10.1128/jb.122.2.764-775.1975. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ptashne K., Cohen S. N. Occurrence of insertion sequence (IS) regions on plasmid deoxyribonucleic acid as direct and inverted nucleotide sequence duplications. J Bacteriol. 1975 May;122(2):776–781. doi: 10.1128/jb.122.2.776-781.1975. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Sharp P. A., Hsu M. T., Otsubo E., Davidson N. Electron microscope heteroduplex studies of sequence relations among plasmids of Escherichia coli. I. Structure of F-prime factors. J Mol Biol. 1972 Nov 14;71(2):471–497. doi: 10.1016/0022-2836(72)90363-4. [DOI] [PubMed] [Google Scholar]
- Yagi Y., Clewell D. B. Plasmid-determined tetracycline resistance in Streptococcus faecalis: tandemly repeated resistance determinants in amplified forms of pAMalpha1 DNA. J Mol Biol. 1976 Apr 15;102(3):583–600. doi: 10.1016/0022-2836(76)90336-3. [DOI] [PubMed] [Google Scholar]