Selective inhibition mechanism of three inhibitors to BRD4 uncovered by molecular docking and molecular dynamics...

Area of Science:

• Biochemistry and Molecular Biology
• Medicinal Chemistry
• Computational Drug Discovery

Background:

• Bromodomain-containing protein 4 (BRD4) is implicated in gene transcription, inflammation, and cancer.
• Understanding selective inhibitor binding to BRD4's bromodomains (BRD4-BD1 and BRD4-BD2) is key for therapeutic development.
• Novel phenoxypyridone compounds show potential as BRD4 inhibitors.

Purpose of the Study:

• To elucidate the molecular mechanism of selective binding of three novel phenoxypyridone inhibitors (Cpd11, Cpd14, Cpd23) to BRD4-BD1 and BRD4-BD2.
• To identify key residues and interaction types driving selective inhibitor binding.
• To provide insights for designing more effective BRD4-targeted therapies.

Main Methods:

• Molecular docking simulations to predict binding modes.
• Molecular dynamics (MD) simulations to analyze protein-ligand dynamics.
• Free energy calculations (MM-GBSA and SIE) to quantify binding affinities.

Main Results:

• The three inhibitors exhibit distinct effects on the internal dynamics of BRD4-BD1 and BRD4-BD2, yet share similar key interactions.
• Specific residues (e.g., Ile146/Val439, Trp81/Trp374) are critical for selective binding to BRD4-BD1 and BRD4-BD2.
• Non-polar interactions, particularly van der Waals forces, are the primary drivers of inhibitor binding to both domains.

Conclusions:

• The study reveals the detailed molecular interactions governing the selective binding of phenoxypyridone inhibitors to BRD4 bromodomains.
• Key residues and interaction types provide a foundation for the rational design of novel, highly selective BRD4 inhibitors.
• Findings support the development of targeted therapies for diseases involving BRD4, particularly focusing on BRD4-BD2 selectivity.