Molecular view of ligands specificity for CAG repeats in anti-Huntington therapy

Area of Science:

• Neuroscience
• Computational Chemistry
• Molecular Biology

Background:

• Huntington's disease (HD) is a fatal neurodegenerative disorder with no cure.
• HD is characterized by expanded CAG repeats in Huntingtin mRNA.
• Targeting these expanded repeats is a potential therapeutic strategy, but lacks structural guidance.

Purpose of the Study:

• To investigate the binding pose and affinity of two small molecules targeting expanded CAG repeats.
• To provide structural insights into ligand-RNA interactions for rational drug design.
• To understand the molecular basis for differential ligand affinities.

Main Methods:

• Well-tempered metadynamics-based free energy calculations were employed.
• Computational modeling was used to study ligand-RNA interactions.
• Simulations were validated against experimental binding affinity data (Kd values).

Main Results:

• Calculations accurately reproduced experimental binding affinities for two distinct ligands.
• The study elucidated the specific recognition patterns between ligands and CAG repeats.
• A molecular explanation for the significant difference in affinity between the two ligands was uncovered.

Conclusions:

• Computational approaches can accurately predict ligand binding to expanded CAG repeats.
• Structural insights gained can guide the optimization of ligands for improved selectivity.
• This work provides a foundation for structure-based drug discovery for Huntington's disease.