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pSAR1, a natural plasmid from Streptomyces arenae, shows rapid increase and decrease of copy numbers on changes of
M Braxenthaler1, B Poetsch, K U Fröhlich
1Physiologisch-chemisches Institut, University of Tübingen, F.R.G.
FEMS Microbiology Letters
|October 15, 1991
Summary
A natural plasmid, pSAR1, from Streptomyces arenae was studied. Its high copy number correlates with antibiotic production, with rapid regulation suggesting catalytic mechanisms.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Streptomyces arenae TU469 produces the antibiotic pentalenolactone.
- Natural plasmids play roles in microbial secondary metabolism and adaptation.
- Plasmid copy number regulation is crucial for maintaining genetic elements.
Purpose of the Study:
- To characterize the natural plasmid pSAR1 isolated from Streptomyces arenae TU469.
- To investigate the relationship between pSAR1 copy number and pentalenolactone production.
- To explore the regulatory mechanisms of pSAR1 copy number control.
Main Methods:
- Isolation and characterization of the natural plasmid pSAR1.
- Restriction analysis for size estimation (approx. 80 kbp).
- Culturing of Streptomyces arenae under varying conditions to observe copy number changes.
Main Results:
- Plasmid pSAR1 exists in two copy-number states, differing by at least 10-fold.
- High copy numbers of pSAR1 are strongly correlated with pentalenolactone antibiotic production.
- Rapid decrease in copy number (within 1 hour) observed upon changing culture conditions, with evidence of degradational intermediates.
Conclusions:
- Plasmid pSAR1 copy number is tightly regulated in Streptomyces arenae.
- The regulation involves rapid, potentially catalytic mechanisms, indicated by fast kinetics and intermediates.
- pSAR1 copy number control is linked to the production of the antibiotic pentalenolactone, suggesting a functional role in secondary metabolism.