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Minor-groove binding models for acetylaminofluorene modified DNA
R Shapiro1, B E Hingerty, S Broyde
1Chemistry Dept., New York University, NY 10003.
Journal of Biomolecular Structure & Dynamics
|December 1, 1989
Summary
Computational studies reveal new DNA structures formed by acetylaminofluorene (AAF) modification of guanine. The favored "wedge" model minimizes helix deformation, with AAF nestled in the minor groove.
Area of Science:
- Molecular Biology
- Computational Chemistry
- Structural Bioinformatics
Background:
- Chemical modification of DNA, such as by acetylaminofluorene (AAF) at the guanine C8 position, can alter DNA structure and function.
- Understanding the precise three-dimensional arrangements of modified DNA is crucial for predicting biological consequences.
Purpose of the Study:
- To computationally identify and energetically assess various structural models of DNA modified by acetylaminofluorene (AAF) at the C8 position of guanine.
- To investigate these structures across three distinct nonamer DNA sequences.
Main Methods:
- Minimized potential energy calculations were used to explore and evaluate different DNA structural models.
- Analysis focused on B-DNA and Z-DNA helices, including syn guanine configurations.
Main Results:
- Two novel syn guanine structures with AAF in the B-DNA minor groove were identified.
- One structure features Hoogsteen base pairing and significant helix bending; the other, the 'wedge' model, shows a single hydrogen bond and minimal helix distortion.
- Both identified structures, along with deprotonated cytosine variants, are energetically significant across all tested sequences, with the wedge model being most favored.
Conclusions:
- The study elucidates energetically favorable conformations of AAF-modified DNA, highlighting the 'wedge' model as a significant structural outcome.
- These findings contribute to understanding the structural impact of bulky aromatic adducts on DNA, relevant for carcinogenicity and repair mechanisms.