A prerequisite to the development of gene cloning and expression of homologous and heterologous genes in any organism is the identification of a suitable vector for the introduction and stable maintenance of cloned DNA in the host. During progressive application of rDNA technology in Streptomyces, the problems of efficient introduction of vectors by transformation of protoplasts were solved. However, the problems of stable maintenance of the cloned DNA in the host still persist. Streptomyces strains are often genetically unstable (Schrempf et al., 1987) and their mycelial growth habit hampers the study of plasmid instability. In general, two types of instability are observed and studied in gram-positive bacteria: one corresponding to the loss of the entire vector from the cell, the other to rearrangements, most often deletions of plasmid sequences. The first was named segregational, the second structural plasmid instability (Ehrlich et al., 1987). Recently attempts to study the problems of plasmid segregational instability in Streptomyces were reported. Because of their mycelial growth habit and irregular cell division, plasmids do not segregate into individual cells after replication. This fact makes investigation of plasmid inheritance difficult in Streptomyces. Many vectors currently used in Streptomyces are derivatives of pIJ101 (Kieser et al., 1982). It is interesting to note that no evidence exists for a par locus on such plasmids which replicate via rolling circle, i.e. there are no membrane attachment sites that physically aid segregation of sufficient numbers of plasmids to be established in each daughter cell (Cesareni et al., 1987). In these plasmids, stability seems to be coupled with replication and not with a discrete par-like function (Gruss and Ehrlich, 1989).


Structural Instability Industrial Microorganism Illegitimate Recombination Stable Maintenance Plasmid Instability 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Anderson, P., 1987, Twenty years of illegitimate recombination. Genetics 115, 581: 584.Google Scholar
  2. Casareni, G., M. Anceschi, L. Castagnoli, F. Felici, M. Helmer Citterich, J. Hughes, D. Kirk, J. Murray, N. Rossi, M. Scarpa and L. Spinelli, 1987, E. coli plasmid stability and control of copy number. In: “Genetics of Industrial Microorganisms”, Part A (M. Alacevié, D. Hranueli and Z. Toman, eds.), p. 247: 257. PLIVA, Zagreb.Google Scholar
  3. Franklin, N. C., 1967, Extraordinary recombinational events in Escherichia coli. Their independence of rec+ function. Genetics 55, 699: 707.Google Scholar
  4. Ehrlich, S. D., D. Brunier, L. Janniere, B. Michel, Ph. Noirot, M. A. Petit and H. to Riele, 1987, Structural instability of genes cloned in Bacillus subtilis. In: “Genetics of Industrial Microorganisms” Part B (M. Alacevié, D. Hranueli and Z. Toman, eds.) pp. 93: 96. PLIVA, Zagreb.Google Scholar
  5. Gellert, M., 1981, DNA topoisomerases. Annu. Rev. Biochem. 54, 665: 697.Google Scholar
  6. Gellert, M., K. Mizuuchi, M. H. O’Dea, R. Itoh and J. Tomizawa, 1977, Nalidixic acid resistance: a second genetic character involved in DNA gyrase activity. Proc. Natl. Acad. Sci. USA 74, 4772: 4776.Google Scholar
  7. Gruss, A. and S. D. Ehrlich, 1989, The family of highly interrelated single-stranded deoxyribonucleic acid plasmids. Microbiol. Rev. 53, 231: 241.Google Scholar
  8. Mizuuchi, K., M. H. O’Dea and M. Gellert, 1978, DNA gyrase: subunit structure and ATPase of the purified enzyme. Proc. Natl. Acad. Sci. USA 75, 5960: 5963.Google Scholar
  9. Pigac, J., D. Vujaklija, Z. Toman, V. Gamulin and H. Schrempf, 1988, Structural instability of a bifunctional plasmid pZG1 and single-stranded DNA formation in Streptomyces. Plasmid 19, 222: 230.Google Scholar
  10. Schauer, A., M. Raves, R. Santamaria, J. Guijarro, E. Lawlor, C. Mendez, K. Chater and R. Losick, 1988, Visualizing gene expression in time and space in the filamentous bacterium Streptomyces coelicolor. Science 240, 768: 772.Google Scholar
  11. Schrempf, H., P. Dyson, M. Betzler, T. Kumar and P. Groitl, 1987, Amplification and deletion of DNA-sequences in Streptomyces. In: “Genetics of Industrial Microorganisms” Part A (M. Alacevié, D. Hranueli and Z. Toman, eds.), pp. 177: 184. PLIVA, Zagreb.Google Scholar
  12. Sugino, A., N. P. Higgins, P. O. Brown, C. L. Peebles and N. R. Cozzarelli, 1977, Mechanisms of action of nalidixic acid: purification of Echerichia coli nalA gene product and its relationship to DNA gyrase and a novel nicking-closing enzyme. Proc. Natl. Acad. Sci. USA 74, 4767: 4771.Google Scholar
  13. Sugino, A., N. P. Higgins, P. O. Brown, C. L. Peebles and N. R. Cozzarelli, 1978, Energy coupling in DNA gyrase and the mechanism of action of novobiocin. Proc. Natl. Acad. Sci. USA 75, 4838: 4842.Google Scholar
  14. Wang, J. C., 1985, DNA topoisomerases. Annu. Rev. Biochem. 54, 665: 697.Google Scholar
  15. Wolfson, J. S. and D. C. Hooper, 1985, The fluoroquinolones: structure, mechanism of action and resistance, and spectra of activity in vitro. Antimicrob. Agents Chemother. 28, 581: 586.Google Scholar

Copyright information

© Plenum Press, New York 1991

Authors and Affiliations

  • Jasenka Pigac
    • 1
  1. 1.PLIVA Research InstituteZagrebYugoslavia

Personalised recommendations