DNA polymerases of tumor virus: specific effect of ethidium bromide on the use of different synthetic templates
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Abstract:
The DNA polymerase enzymes from avian, murine, and feline RNA tumor viruses can be distinguished by their ability to read specific, synthetic primertemplates. The copying of templates containing adenylic and thymidylic acids by all these DNA polymerases is inhibited by ethidium bromide, though this compound affects the polymerases from mammalian tumor viruses much more than the enzyme from avian tumor viruses. Conversely, ethidium bromide stimulates the ability of the enzymes from avian tumor viruses to use primertemplates containing only guanylic and cytidylic acids, whereas the mammalian tumor virus enzymes are moderately inhibited.
Insights
Avian and mammalian tumor virus DNA polymerases differ in template usage and response to ethidium bromide. These distinct characteristics help differentiate these viral enzymes.
Area of Science:
- Virology
- Molecular Biology
- Enzymology
Background:
- RNA tumor viruses possess unique DNA polymerase enzymes.
- These enzymes play a crucial role in viral replication and genetic material synthesis.
Purpose of the Study:
- To differentiate DNA polymerase enzymes from avian, murine, and feline RNA tumor viruses.
- To investigate the differential effects of ethidium bromide on these viral DNA polymerases using synthetic templates.
Main Methods:
- Utilized synthetic primer-templates composed of specific nucleotide combinations (adenylic/thymidylic acids and guanylic/cytidylic acids).
- Assessed the activity of DNA polymerases from avian, murine, and feline RNA tumor viruses in copying these templates.
- Quantified the effects of ethidium bromide, an intercalating agent, on enzyme activity.
Main Results:
- All tested DNA polymerases showed inhibition of template copying (adenylic and thymidylic acids) by ethidium bromide.
- Mammalian tumor virus DNA polymerases were significantly more affected by ethidium bromide than avian tumor virus DNA polymerases.
- Ethidium bromide stimulated avian tumor virus DNA polymerases on guanylic and cytidylic acid templates, while moderately inhibiting mammalian enzymes.
Conclusions:
- The differential response of DNA polymerases to synthetic templates and ethidium bromide provides a method for distinguishing avian from mammalian viral enzymes.
- Ethidium bromide's varying effects highlight distinct structural or functional properties of avian versus mammalian viral DNA polymerases.