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Catalytic editing properties of DNA polymerases
B Canard1, B Cardona, R S Sarfati
1Faculté de Médecine, Unité de Recherche Associée-Centre National de la Recherche Scientifique 1462, Nice, France.
Summary
3'-esterified deoxynucleoside triphosphates act as false chain terminators. DNA polymerases can extend DNA chains using these modified nucleotides, revealing their catalytic versatility at the nascent strand's 3' end.
Area of Science:
- Biochemistry
- Molecular Biology
- Enzymology
Background:
- 2',3'-dideoxynucleotides are known DNA chain terminators.
- DNA polymerases play a crucial role in DNA replication and repair.
Purpose of the Study:
- To investigate the catalytic versatility of DNA polymerases at the 3' end of nascent DNA strands.
- To explore the use of modified deoxynucleoside triphosphates (dNTPs) as substrates for DNA polymerases.
Main Methods:
- Enzymatic incorporation assays using modified dNTPs and DNA polymerases.
- Utilizing T7 DNA polymerase lacking 3'-to-5' exonuclease activity.
- Employing reporter groups conjugated to dTTP at the 3' position.
Main Results:
- 3'-esterified dNTPs are incorporated by DNA polymerases, including HIV reverse transcriptase, leading to chain extension rather than termination.
- DNA polymerases can extend DNA primers esterified at the 3' position.
- T7 DNA polymerase can cleave 3'-reporter groups, restoring chain termination.
Conclusions:
- DNA polymerases exhibit significant catalytic versatility at the 3' end of the growing DNA chain.
- Modified nucleotide analogues can be processed by DNA polymerases in unexpected ways.
- These findings expand the understanding of polymerase mechanisms and nucleotide analogue interactions.