Related Experiment Videos
Negatively supercoiled DNA from plants infected with a single-stranded DNA virus
Biochemical and Biophysical Research Communications
|February 14, 1984
Summary
Researchers developed a method to isolate covalently closed circular DNA from geminivirus-infected plants. This DNA was found to be negatively supercoiled and sensitive to S1 nuclease, indicating secondary structures.
Area of Science:
- Plant virology
- Molecular biology
- Biochemistry
Background:
- Geminiviruses, such as tomato golden mosaic virus, are plant pathogens that replicate their DNA within infected host cells.
- Understanding the structure of viral DNA is crucial for comprehending viral replication and developing control strategies.
- Covalently closed circular DNA (cccDNA) is a key intermediate in the replication cycle of many viruses.
Purpose of the Study:
- To describe a method for isolating covalently closed circular double-stranded DNA (cccDNA) from plants infected with tomato golden mosaic virus (TGMV).
- To characterize the superhelical state and structural properties of the isolated TGMV cccDNA.
Main Methods:
- Isolation of cccDNA from TGMV-infected plant tissues.
- Ethidium bromide titration to determine superhelical density.
- Treatment with S1 nuclease to assess DNA structure and sensitivity.
Main Results:
- A method for isolating TGMV cccDNA was successfully established.
- Ethidium bromide titration revealed the DNA to be negatively supercoiled, with a superhelical density of -0.062.
- The supercoiled DNA exhibited sensitivity to S1 nuclease, converting to open circular and linear forms, indicating the presence of secondary structures.
Conclusions:
- The isolated TGMV cccDNA exists in a negatively supercoiled state.
- The DNA possesses S1 nuclease-sensitive secondary structures, which may play a role in viral replication or DNA packaging.