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Bacteriophage fd gene-2 protein. Processing of phage fd viral strands replicated by phage T7 enzymes
Abstract:
Bacteriophage T7 gene 4 protein and DNA polymerase of the phage were used to study the viral strand synthesis of bacteriophage fd in vitro. Cleavage of supercoiled phage fd replicative form (RF) by fd gene 2 protein produced a nick at a specific site in the viral strand. The cleaved double-stranded DNA was unwound by T7 gene 4 protein and T7 DNA polymerase and the 3' end of the nicked strand simultaneously extended according to the rolling circle mechanism. After a complete round of DNA synthesis fd gene 2 protein cleaved the viral strand presumably at the same site, where the endonuclease cuts fd RF I, and subsequently sealed the single-stranded linear DNA into a circle. The reaction products were analyzed by velocity sedimentation, gel electrophoresis and electron microscopy. Most of the single-stranded DNA synthesized was circular. No host proteins were required for the formation of the single-stranded circles. Strand switching of the T7 DNA polymerase indicated by double-stranded tails of the rolling circle structures reduced the yield of viral single-stranded circles in this enzyme system.
Insights
Bacteriophage T7 gene 4 protein and DNA polymerase facilitate bacteriophage fd viral strand synthesis in vitro. This rolling circle mechanism efficiently produces single-stranded DNA circles without host proteins.
Area of Science:
- Molecular Biology
- Virology
- Biochemistry
Background:
- Bacteriophage fd replication involves specific protein interactions.
- Understanding viral DNA synthesis is crucial for molecular biology.
Purpose of the Study:
- To investigate the in vitro viral strand synthesis of bacteriophage fd.
- To elucidate the roles of bacteriophage T7 gene 4 protein and DNA polymerase in this process.
Main Methods:
- Utilized bacteriophage T7 gene 4 protein and DNA polymerase.
- Employed bacteriophage fd gene 2 protein for DNA cleavage and circularization.
- Analyzed reaction products using velocity sedimentation, gel electrophoresis, and electron microscopy.
Main Results:
- Demonstrated rolling circle DNA synthesis of the viral strand.
- Showed efficient production of single-stranded DNA circles.
- Identified that T7 DNA polymerase strand switching can reduce yield.
Conclusions:
- Bacteriophage T7 proteins can support bacteriophage fd viral strand synthesis in vitro.
- The rolling circle mechanism is effective for producing single-stranded DNA circles.
- Host proteins are not required for this specific DNA synthesis pathway.