Related Experiment Videos
Coding and conformational properties of oligonucleotides modified with the carcinogen N-2-acetylaminofluorene
Abstract:
The present studies were undertaken to determine the mechanism by which attachment of the carcinogen N-2-acetylaminofluorene to guanosine residues in nucleic acids distors their structure and function. Oligonucleotides were modified with N-acetoxy-2-acetylaminofluorene, repurified, and their base compositions analyzed. Evidence is presented that acetylaminofluorene residues bound to guanosines in GpUpU, ApApG, or poly (U,G) inactivates their function in codon recognition. Circular dichroism spectra suggest that this is caused by gross conformational changes in these compounds involving both a rotation about the glycosidic bond of guanosine residues bearing N-2-acetylaminofluorene, as well as stacking interactions between the drug and bases adjacent to the substituted guanosine.
Insights
The carcinogen N-2-acetylaminofluorene binds to guanosine in nucleic acids, altering their structure and function. This binding disrupts codon recognition and causes significant conformational changes in oligonucleotides.
Area of Science:
- Molecular Biology
- Biochemistry
- Chemical Carcinogenesis
Background:
- Carcinogens can alter nucleic acid structure and function.
- Understanding the mechanism of carcinogen-DNA interaction is crucial for assessing risk.
Purpose of the Study:
- To elucidate the mechanism by which N-2-acetylaminofluorene (AAF) binding to guanosine residues affects nucleic acid structure and function.
- To investigate the conformational changes induced by AAF modification in oligonucleotides.
Main Methods:
- Modification of oligonucleotides with N-acetoxy-2-acetylaminofluorene.
- Repurification and base composition analysis of modified oligonucleotides.
- Assessment of functional inactivation in codon recognition.
- Circular dichroism spectroscopy to analyze conformational changes.
Main Results:
- AAF residues bound to guanosines in GpUpU, ApApG, and poly (U,G) were shown to inactivate their function in codon recognition.
- Circular dichroism spectra indicated gross conformational changes.
- These changes involve rotation about the glycosidic bond of guanosine and stacking interactions between AAF and adjacent bases.
Conclusions:
- AAF binding to guanosine residues induces significant structural alterations in nucleic acids.
- These structural changes lead to functional impairment, specifically in codon recognition.
- The study provides mechanistic insights into the disruptive effects of chemical carcinogens on nucleic acid integrity.