Abstract
Six lac elements originally contained in Salmonella strains were transferred to Escherichia coli WR3026. All of the six E. coli strains that received one of the lac elements were observed to contain supercoiled, circular deoxyribonucleic acid (DNA) when examined by the dye-buoyant density method. Segregants of each of these E. coli WR3026 strains that had lost the ability to utilize lactose, when examined in the same manner as the lactose-fermenting strains, were not observed to contain these supercoiled, circular DNA molecules. Thus the DNA of the lac elements is maintained in E. coli WR3026 in the supercoiled, circular form. Molecular weights of the supercoiled, circular molecules isolated from strains carrying the lac elements were determined by sucrose density gradient centrifugation to be 30 million to 56 million. The calculated number of copies per chromosome of the lac elements varied from 1.4 to 3.7, depending upon the particular lac element examined. Each of the elements was determined to have a guanine plus cytosine composition of 50%. All six of the E. coli WR3026 strains containing a transmissible lac element were tested with the E. coli male-specific phage, R-17, and the E. coli female-specific phage, φII, and did not respond to either of these phages as do F-containing derivatives of E. coli K-12.
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- Clewell D. B., Helinski D. R. Evidence for the existence of the colicinogenic factors E2 and E3 as supercoiled circular DNA-protein relaxation complexes. Biochem Biophys Res Commun. 1970 Aug 11;40(3):608–613. doi: 10.1016/0006-291x(70)90947-2. [DOI] [PubMed] [Google Scholar]
- Cohen S. N., Miller C. A. Non-chromosomal antibiotic resistance in bacteria. II. Molecular nature of R-factors isolated from Proteus mirabilis and Escherichia coli. J Mol Biol. 1970 Jun 28;50(3):671–687. doi: 10.1016/0022-2836(70)90092-6. [DOI] [PubMed] [Google Scholar]
- Cuzin F. Un bactériophage spécifique du type sexuel F- d'Escherichia coli K 12. C R Acad Sci Hebd Seances Acad Sci D. 1965 Jun 14;260(24):6482–6485. [PubMed] [Google Scholar]
- Datta A., Parker C. D., Wohlhieter J. A., Baron L. S. Isolation and characterization of the fertility factor P of Vibrio cholerae. J Bacteriol. 1973 Feb;113(2):763–771. doi: 10.1128/jb.113.2.763-771.1973. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Easterling S. B., Johnson E. M., Wohlhieter J. A., Baron L. S. Nature of lactose-fermenting Salmonella strains obtained from clinical sources. J Bacteriol. 1969 Oct;100(1):35–41. doi: 10.1128/jb.100.1.35-41.1969. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Helinski D. R., Clewell D. B. Circular DNA. Annu Rev Biochem. 1971;40:899–942. doi: 10.1146/annurev.bi.40.070171.004343. [DOI] [PubMed] [Google Scholar]
- PARANCHYCH W., GRAHAM A. F. Isolation and properties of an RNA-containing bacteriophage. J Cell Comp Physiol. 1962 Dec;60:199–208. doi: 10.1002/jcp.1030600303. [DOI] [PubMed] [Google Scholar]
- Radloff R., Bauer W., Vinograd J. A dye-buoyant-density method for the detection and isolation of closed circular duplex DNA: the closed circular DNA in HeLa cells. Proc Natl Acad Sci U S A. 1967 May;57(5):1514–1521. doi: 10.1073/pnas.57.5.1514. [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]
- Vinograd J., Lebowitz J. Physical and topological properties of circular DNA. J Gen Physiol. 1966 Jul;49(6):103–125. doi: 10.1085/jgp.49.6.103. [DOI] [PMC free article] [PubMed] [Google Scholar]