Related Experiment Videos
Triple-helix formation by alpha oligodeoxynucleotides and alpha oligodeoxynucleotide-intercalator conjugates
J S Sun1, C Giovannangeli, J C François
1Laboratoire de Biophysique, Muséum National d'Histoire Naturelle, Institut National de la Santé et de la Recherche Médicale, Paris, France.
Summary
Synthetic alpha oligodeoxynucleotides form stable DNA triple helices and inhibit restriction enzymes. These nuclease-resistant molecules offer new ways to control gene expression at the DNA level.
Area of Science:
- Molecular Biology
- Biochemistry
- Genetics
Background:
- Homopyrimidine oligonucleotides can bind to DNA major grooves at homopurine.homopyrimidine sequences, forming local triple helices.
- Natural (beta) oligodeoxynucleotides are susceptible to nucleases, limiting their therapeutic applications.
- Alpha anomers of nucleotide units offer a potential strategy to enhance nuclease resistance.
Purpose of the Study:
- To synthesize and characterize nuclease-resistant alpha oligodeoxynucleotides.
- To investigate the binding orientation and triple helix stabilization of alpha oligodeoxynucleotides.
- To evaluate the potential of alpha oligodeoxynucleotides for gene expression control, specifically targeting HIV proviral DNA.
Main Methods:
- Synthesis of an 11-mer alpha oligodeoxynucleotide (5'-d(TCTCCTCCTTT)-3') and comparison with its beta anomer.
- Attachment of an intercalating agent to the 3' end of the alpha oligodeoxynucleotide.
- Testing the inhibitory effect of alpha oligodeoxynucleotides on a restriction enzyme targeting a specific DNA sequence in HIV proviral DNA.
Main Results:
- The alpha oligodeoxynucleotide binds to the DNA major groove in an antiparallel orientation, unlike the parallel orientation of beta oligonucleotides.
- Attaching an intercalating agent significantly stabilized the triple helix formed by the alpha oligodeoxynucleotide.
- The modified alpha oligodeoxynucleotide inhibited a restriction enzyme ~20 times more effectively than the unmodified version, demonstrating potent gene targeting capability.
Conclusions:
- Nuclease-resistant alpha oligodeoxynucleotides can form stable DNA triple helices with specific DNA sequences.
- These modified oligonucleotides exhibit enhanced efficiency in inhibiting DNA-modifying enzymes.
- Alpha oligodeoxynucleotides represent a promising tool for controlling gene expression at the DNA level, with potential applications in antiviral therapies.