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Infecting bacteriophage mu DNA forms a circular DNA-protein complex
Journal of Molecular Biology
|June 25, 1983
Summary
A novel circular DNA-protein complex of bacteriophage Mu DNA has been identified in infected cells. This complex, protected by a ~64 kDa protein, may represent the integrative precursor of infecting Mu DNA.
Area of Science:
- Molecular Biology
- Virology
- Bacteriophage Research
Background:
- Bacteriophage Mu is a versatile genetic element.
- Understanding the DNA forms during bacteriophage infection is crucial for molecular biology.
Purpose of the Study:
- To investigate the physical nature of a unique Mu DNA form observed during infection.
- To characterize the composition and properties of this Mu DNA complex.
Main Methods:
- Neutral sucrose gradient sedimentation
- Electron microscopy
- Biochemical treatments (Pronase, phenol, SDS)
- Exonuclease digestion assays
- Transfection of E. coli spheroplasts
Main Results:
- A circular, supertwisted Mu DNA-protein complex was identified.
- The complex is resistant to exonucleases due to a non-covalently bound protein (~64 kDa).
- This circular form is found in mature phage particles and is highly transfectious.
Conclusions:
- The identified DNA-protein complex is not covalently closed and likely represents an intermediate in bacteriophage Mu DNA replication or integration.
- The associated protein plays a role in circularization and protection of the Mu DNA termini.