Related Experiment Videos
Sequence-specific actinomycin D binding to single-stranded DNA inhibits HIV reverse transcriptase and other
1Department of Chemistry, Institute of Molecular Biophysics, Florida State University, Tallahassee, 32306-3006, USA.
Biochemistry
|March 19, 1996
Summary
The anticancer drug actinomycin D binds single-stranded DNA, forming stable complexes that halt DNA polymerase activity. This binding may inhibit transcription and offer new antiviral strategies against viruses like HIV.
Area of Science:
- Biochemistry
- Molecular Biology
- Anticancer Drug Research
Background:
- Actinomycin D is an anticancer drug known to intercalate into double-stranded DNA.
- Its interaction with single-stranded DNA (ssDNA) and effect on DNA polymerases are less understood.
Purpose of the Study:
- To investigate the binding of actinomycin D to ssDNA.
- To determine the impact of actinomycin D binding on primer extension by various DNA polymerases.
- To explore potential antiviral applications of actinomycin D's ssDNA binding.
Main Methods:
- Primer extension assays were performed using recombinant ssDNA templates containing all possible base quartets.
- Single-stranded DNA was generated using T7 gene 6 exonuclease.
- The effects of actinomycin D on primer extension by HIV-1 reverse transcriptase, Sequenase, Klenow fragment, and Vent (exo-) DNA polymerase were analyzed.
Main Results:
- Actinomycin D formed high-affinity, kinetically stable complexes with ssDNA.
- These complexes caused polymerase pauses, primarily near G+C-rich regions and GpC steps.
- Different polymerases exhibited varied responses to actinomycin D binding, indicating differential polymerase sensitivity.
- Photoaffinity labeling revealed that covalent adducts completely inhibited primer extension.
Conclusions:
- Actinomycin D inhibits transcription elongation by binding to ssDNA within open transcription complexes.
- ssDNA binding by actinomycin D or its analogs could be a strategy to combat viruses with ssDNA intermediates, such as HIV.