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Mycoplasma virus P1 has a linear, double-stranded DNA genome with inverted terminal repeats
1Department of Microbiology, University of Alabama at Birmingham 35294, USA.
Abstract:
Mycoplasma virus P1 is a tailed, polyhedral virus isolated from Mycoplasma pulmonis. To characterize the P1 genome, stocks of virus were prepared free of host cell nucleic acids. A single DNA species of 11.3 kb that was shown by plaque hybridization to be of P1 origin was extracted from the virus. Efficient isolation of P1 DNA required digestion with proteolytic enzymes prior to phenol extraction. Although P1 DNA was double-stranded and linear following such treatment, it was resistant to digestion with the 5'-specific lambda exonuclease. Electron microscopic analysis indicated that globular material is complexed to the ends of P1 DNA. The globular material was not observed on protease-treated P1 DNA molecules, suggesting that it is composed of protein. Removal of the putative terminal protein by chemical treatment allowed the cloning of the P1 DNA ends, and nucleotide sequence analysis revealed that these ends contain a 350-bp inverted terminal repeat.
Insights
Mycoplasma virus P1 DNA, a 11.3 kb genome, features unique terminal proteins. These proteins protect the DNA ends, which contain a 350-bp inverted terminal repeat, crucial for viral replication.
Area of Science:
- Virology
- Molecular Biology
- Genomics
Background:
- Mycoplasma virus P1 is a tailed, polyhedral virus.
- Characterization of viral genomes is essential for understanding viral replication and evolution.
Purpose of the Study:
- To characterize the genome of Mycoplasma virus P1.
- To identify and analyze the structure of the P1 viral DNA and its terminal elements.
Main Methods:
- Virus purification and nucleic acid extraction.
- Plaque hybridization for DNA origin confirmation.
- Enzymatic digestion (proteolytic, lambda exonuclease) and electron microscopy.
- Chemical treatment for terminal protein removal and DNA end cloning.
- Nucleotide sequence analysis.
Main Results:
- A single 11.3 kb double-stranded linear DNA species of P1 origin was isolated.
- P1 DNA showed resistance to 5'-specific lambda exonuclease, suggesting end protection.
- Electron microscopy revealed globular material (protein) at the DNA ends.
- Chemical treatment removed terminal proteins, enabling cloning and sequencing.
- Sequence analysis identified a 350-bp inverted terminal repeat at the DNA ends.
Conclusions:
- Mycoplasma virus P1 possesses a linear 11.3 kb genome with proteinaceous ends.
- The identified inverted terminal repeat is a key structural feature of the P1 genome.