Mg2+ in the major groove modulates B-DNA structure and dynamics

Area of Science:

• Structural Biology
• Biophysics
• Computational Chemistry

Background:

• Divalent cations, like magnesium (Mg2+), play crucial roles in DNA structure and function.
• The DNA major groove is a key site for cation binding and recognition.

Purpose of the Study:

• To investigate the structural and dynamic effects of Mg2+ binding within the DNA major groove.
• To elucidate the specific interactions between Mg2+ and DNA sequences, particularly ApG sites.

Main Methods:

• Analysis of a large dataset of B-DNA crystallographic structures.
• Molecular dynamics simulations of DNA oligomers with and without Mg2+.

Main Results:

• Mg2+ preferentially binds to the DNA major groove, interacting with ApG and TpG sequences.
• Hydrated Mg2+ forms stable intra-strand cross-links between purines at ApG steps.
• Mg2+ binding modulates DNA dynamics by increasing the BII phosphate group population at the 5'-neighboring step.

Conclusions:

• Mg2+ binding in the DNA major groove locally influences DNA conformation and dynamics.
• These findings provide a basis for understanding how DNA distortions are stabilized in protein-DNA complexes.