Structural insight into antisense gapmer-RNA oligomer duplexes through molecular dynamics simulations.

Area of Science:

• Biochemistry
• Molecular Biology
• Computational Chemistry

Background:

• Antisense technology is rapidly advancing with increasing clinical trials.
• Phosphorothioate (PS) modification enhances nuclease resistance.
• 2'-4' conformationally restricted nucleosides (LNA, MOE) offer improved binding affinity and toxicity profiles.

Purpose of the Study:

• To investigate the structural dynamics, stability, and solvation properties of various antisense gapmer/target-RNA duplexes using molecular dynamics (MD) simulations.
• To compare the effects of different nucleoside modifications (LNA, MOE, PS-DNA) on duplex stability and binding affinity.
• To correlate structural properties with potential therapeutic efficacy and toxicity.

Main Methods:

• Classical molecular dynamics (MD) simulations.
• Analysis of six different antisense gapmer/target-RNA oligomer duplexes.
• Calculation of helical parameters, free energy, and solvent accessible surface area (SASA).

Main Results:

• LNA and MOE nucleotides exhibit A-form helix structures, while PS-DNA resembles a B-form helix.
• Free energy calculations indicate stronger RNA binding for LNA-containing oligomers compared to other modifications.
• MOE modifications showed lower binding affinity but higher SASA, potentially influencing toxicity.

Conclusions:

• LNA modifications provide superior binding affinity to target RNA, aligning with experimental findings.
• MOE modifications, despite lower binding affinity, may contribute to favorable toxicity profiles, as seen in Mipomersen.
• MD simulations provide valuable insights into the structure-function relationships of modified antisense oligonucleotides.