Carcinogenesis, Vol. 21, No. 9, 1727-1736,
September 2000
© 2000 Oxford University Press
Carcinogenesis |
Sequence-dependent conformational perturbation in DNA duplexes containing an
AT mismatch using molecular dynamics simulation
Donner Laboratory, Life Sciences Division, Lawrence Berkeley National Laboratory University of California, Berkeley, CA 94720, USA and
1 Institute of Chemistry, Chemical Research Center, Hungarian Academy of Sciences, H-1525 Budapest, PO Box17, Hungary
Previous experiments from this laboratory showed that 1,N6-ethenoadenine (
A) in 15mer DNA oligonucleotide duplexes with GG
AGG and CC
ACC central sequences is repaired 35-fold more efficiently than in duplexes containing AA
AAA and TT
ATT central sequences. This sequence dependence in repair rates appeared to correlate with the observed thermodynamic stability of these duplexes [Hang et al. (1998) J. Biol. Chem., 273, 3340633413]. In the present work, unrestrained molecular dynamics was used to evaluate the sequence-dependent structural features of these duplexes. Explicit solvent and the particle mesh Ewald method were applied for the accurate representation of the electrostatic interactions. The differences observed in the axis- and intra-base pair parameters were primarily localized at the
AT mismatch in all sequences and indicate conformational diversity between the structures. However, all four structures remained in the B-conformational family. In the tip, tilt and propeller twist parameters for the five central base pairs, larger perturbations were found for the two duplexes with
A flanked by A or T bases than for duplexes with
A flanked by G or C bases. As a result of these perturbations, the average global curvature of the AA
AAA and TT
ATT DNA duplexes was larger by ~12° than that of the duplexes with the GG
AGG and CC
ACC central sequences. The observed conformational differences between the duplexes containing A or T and G or C neighbors of
A may contribute to the observed differential enzymatic repair of the same sequences.
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