Molecular dynamics of alkylated DNA

Area of Science:

• Biochemistry
• Molecular Biology
• Computational Chemistry

Background:

• Oligonucleotide structure and function are critical in molecular biology.
• Chemical modifications to nucleobases, such as thymine methylation, can alter DNA properties.
• Understanding these alterations is key to fields like drug design and genetic research.

Purpose of the Study:

• To investigate the impact of O4 atom methylation on thymine within oligonucleotide sequences.
• To compare the stability of modified thymine when paired with guanine versus adenine.
• To evaluate different computational environments for simulating these effects.

Main Methods:

• Molecular dynamics simulations were employed to study two distinct oligonucleotide sequences.
• Three simulation environments were tested: in vacuo with unhydrated ions, in vacuo with hydrated ions, and with an explicit water layer.
• The configuration of the methyl group and the stability of base pairing were analyzed.

Main Results:

• In all simulated environments, the oligonucleotide with methylated thymine paired to guanine exhibited greater stability than when paired to adenine.
• The methyl group on the O4 atom of thymine was consistently observed in a syn configuration relative to the N3 atom.
• Simulation results best matched experimental Nuclear Magnetic Resonance (NMR) data when hydrated counter-ions were used.

Conclusions:

• O4 methylation of thymine influences oligonucleotide stability, favoring pairing with guanine.
• The syn configuration of the methyl group is a consistent structural feature.
• Computational models incorporating hydrated counter-ions provide the most accurate representation of these systems, aligning with experimental findings.