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DNA amplification affects protease production and sporulation in Streptomyces fradiae
T S Ratnakumari1, R Mathumathi, K Dharmalingam
1Department of Biotechnology, School of Biological Sciences, Madurai Kamaraj University, India.
Abstract:
Chloramphenicol resistance is an unstable character in Streptomyces fradiae, since spontaneous chloramphenicol-sensitive (Cmls) mutants arose at very high frequencies. One such Cmls mutant, DM14, showed DNA amplification as well. Extracellular protease activity was tenfold higher in DM14 when compared with its wild-type parent. Protease activity decreased considerably in DM14 when treated with spectinomycin, a treatment that reduces the copy number of amplified units of DNA. Sporulation in DM14 was delayed in the presence of spectinomycin at a concentration of 5 micrograms/ml, whereas the wild type was unaffected at that concentration. The results strongly indicated that the amplified DNA affected the two secondary metabolic functions, viz., protease production and the onset of sporulation in the mutant.
Insights
Chloramphenicol resistance is unstable in Streptomyces fradiae. DNA amplification in mutants led to increased protease production and delayed sporulation, impacting secondary metabolism.
Area of Science:
- Microbiology
- Genetics
- Molecular Biology
Background:
- Chloramphenicol resistance in Streptomyces fradiae is unstable, frequently yielding sensitive mutants.
- One such mutant, DM14, exhibits spontaneous DNA amplification.
Purpose of the Study:
- To investigate the relationship between DNA amplification and secondary metabolic functions in Streptomyces fradiae mutants.
- To understand the impact of amplified DNA on protease production and sporulation.
Main Methods:
- Isolation and characterization of chloramphenicol-sensitive mutants.
- Analysis of DNA amplification and copy number reduction using spectinomycin treatment.
- Quantification of extracellular protease activity.
- Assessment of sporulation onset under varying conditions.
Main Results:
- The Cmls mutant DM14 displayed a tenfold increase in extracellular protease activity compared to the wild type.
- Spectinomycin treatment, which reduced amplified DNA copy number, significantly decreased protease activity in DM14.
- Sporulation was delayed in DM14 when treated with spectinomycin, while the wild type remained unaffected.
Conclusions:
- The amplified DNA in Streptomyces fradiae mutant DM14 directly influences secondary metabolic processes.
- DNA amplification is linked to enhanced protease production and altered sporulation timing.
- These findings highlight the complex interplay between genetic instability and metabolic regulation in Streptomyces.