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EcoRI-sensitive mutation of T7 phage
Molecular & General Genetics : MGG
|January 18, 1977
Summary
Phage T7 DNA is typically resistant to EcoRI restriction endonuclease. However, a specific T7 mutant (T7am28) DNA was found to be cleaved by EcoRI at a single site, indicating a genetic alteration.
Area of Science:
- Molecular Biology
- Virology
- Enzymology
Background:
- Bacteriophage T7 DNA is generally resistant to cleavage by the restriction enzyme EcoRI.
- Restriction enzymes play a crucial role in molecular biology for DNA manipulation.
Purpose of the Study:
- To investigate the susceptibility of phage T7 DNA to EcoRI restriction endonuclease.
- To characterize the site and genetic basis of EcoRI cleavage in a T7 mutant.
Main Methods:
- Enzymatic digestion of phage T7 DNA using restriction endonuclease EcoRI.
- Characterization of cleavage sites on the T7 DNA molecule.
- Genetic mapping of mutations affecting endonuclease sensitivity.
Main Results:
- Phage T7am28 (gene 5) mutant DNA exhibited susceptibility to EcoRI cleavage at a single specific site.
- The EcoRI cleavage site was mapped to 0.46 fractional length from the left end of the T7 DNA molecule.
- The mutation conferring EcoRI sensitivity was found to be distinct from the amber mutation and located between T7am28 and T7am233 (gene 6).
Conclusions:
- A specific mutation in phage T7 DNA can render it sensitive to EcoRI restriction.
- This sensitivity is associated with a unique cleavage site and is genetically separable from other known mutations.
- The findings provide insights into phage T7 genome structure and host-controlled modification systems.