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Sequence-dependent conformational perturbation in DNA duplexes containing an epsilonA.T mismatch using molecular
A B Guliaev1, J Sági, B Singer
1Donner Laboratory, Life Sciences Division, Lawrence Berkeley National Laboratory University of California, Berkeley, CA 94720, USA. abguliaev@lbl.gov
Carcinogenesis
|August 30, 2000
Summary
DNA repair efficiency for 1,N:(6)-ethenoadenine (epsilonA) depends on flanking bases. Molecular dynamics revealed structural differences in DNA duplexes, explaining varied repair rates and highlighting sequence-specific DNA repair mechanisms.
Area of Science:
- Molecular Biology
- Biochemistry
- Structural Biology
Background:
- 1,N:(6)-ethenoadenine (epsilonA) is a DNA adduct repaired with sequence-dependent efficiency.
- Previous studies linked repair rates to DNA duplex thermodynamic stability.
Purpose of the Study:
- To investigate the sequence-dependent structural features of DNA duplexes containing epsilonA using molecular dynamics.
- To understand how DNA structure influences the differential enzymatic repair of epsilonA adducts.
Main Methods:
- Unrestrained molecular dynamics simulations with explicit solvent and particle mesh Ewald method.
- Analysis of axis- and intra-base pair parameters, including tip, tilt, and propeller twist.
- Evaluation of global DNA duplex curvature.
Main Results:
- Conformational diversity was observed at the epsilonA*T mismatch across different sequences, though all remained in the B-conformation.
- Duplexes with epsilonA flanked by adenine (A) or thymine (T) showed greater structural perturbations than those flanked by guanine (G) or cytosine (C).
- AAepsilonAAA and TTepsilonATT duplexes exhibited approximately 12 degrees greater global curvature compared to GGepsilonAGG and CCepsilonACC duplexes.
Conclusions:
- Sequence context significantly impacts DNA duplex structure around the epsilonA adduct.
- Observed structural differences, particularly in curvature and base-pair parameters, correlate with differential enzymatic repair rates.
- These findings provide insights into the molecular mechanisms underlying sequence-specific DNA repair.