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Oligonucleotide-directed switching of DNA polymerases to a dead-end track
A L Guieysse1, D Praseuth, M Grigoriev
1Laboratoire de Biophysique, INSERM U.201--CNRS URA 481, Muséum National d'Histoire Naturelle, Paris, France.
Abstract:
During DNA replication, the presence of oligonucleotides with partial homology to the template strand was shown to induce a switch of the polymerase from the normal template to the oligonucleotide. The latter acted as a dead-end template and led to abortive replication. The only prerequisite was that the oligonucleotide could form 7-9 base pairs with the newly synthesized DNA strand in order to switch templates. The switch occurred when base pairing of the oligonucleotide could take place with the 3'-end of the newly synthesized strand. These results show that oligonucleotides used in antisense or antigene strategies could have unexpected effects on replication. In addition, oligonucleotide-directed abortive replication might play an inhibitory role during PCR experiments on long DNA templates and lead to the amplification of truncated fragments.
Insights
Short DNA sequences called oligonucleotides can unexpectedly halt DNA replication by acting as false templates. This discovery has implications for gene-silencing techniques and PCR amplification of DNA.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- DNA replication is a fundamental biological process.
- Oligonucleotides are short DNA or RNA molecules.
- Antisense and antigene strategies utilize oligonucleotides to modulate gene expression or DNA function.
Purpose of the Study:
- To investigate the effect of homologous oligonucleotides on DNA replication.
- To determine the mechanism by which template switching occurs during replication.
- To assess the potential implications of this phenomenon in molecular biology techniques.
Main Methods:
- In vitro DNA replication assays were performed.
- The influence of synthetic oligonucleotides with partial homology to the template strand was examined.
- The interaction between the newly synthesized DNA strand and the oligonucleotide was analyzed.
Main Results:
- Oligonucleotides with 7-9 base pair homology to the nascent DNA strand induced polymerase template switching.
- The oligonucleotide acted as a dead-end template, leading to abortive replication.
- Template switching occurred preferentially when the oligonucleotide could base pair with the 3'-end of the newly synthesized strand.
Conclusions:
- Oligonucleotides can interfere with DNA replication by acting as alternative templates.
- This mechanism may lead to unintended consequences in gene-targeting therapies like antisense and antigene strategies.
- Oligonucleotide-induced abortive replication could inhibit PCR amplification and result in truncated DNA fragments.