Probing the binding mechanism of Mnk inhibitors by docking and molecular dynamics simulations

Area of Science:

• Biochemistry
• Medicinal Chemistry
• Computational Biology

Background:

• Mitogen-activated protein kinases-interacting kinase 1 and 2 (Mnk1/2) phosphorylate and activate the oncogene eukaryotic initiation factor 4E (eIF4E).
• Elevated levels of phosphorylated eIF4E are linked to various cancers, making Mnk1/2 potential therapeutic targets.
• Novel imidazopyridine and imidazopyrazine derivatives have been synthesized as Mnk1/2 inhibitors.

Purpose of the Study:

• To computationally model the inhibition of Mnk1/2 kinase activity by novel imidazopyridine and imidazopyrazine derivatives.
• To understand the binding modes and key interactions responsible for the inhibitory potency of these compounds.

Main Methods:

• Homology modeling of Mnk1/2 kinases.
• Molecular docking and dynamics simulations.
• Free energy calculations (binding free energy, ΔGPred).

Main Results:

• All tested compounds exhibited similar binding modes within the Mnk1/2 active sites, anchored by hydrogen bonds to the hinge regions.
• Key hydrogen bond interactions involving specific lysine and serine residues were identified as crucial for inhibitor potency and stability.
• Computed binding free energies correlated well with experimental bioactivity data (pIC50), with r² values of 0.70 for Mnk1 and 0.68 for Mnk2.
• Van der Waals energies and entropic effects were found to be dominant contributors to the binding free energy.

Conclusions:

• The computational models accurately reflect the experimental bioactivity of the novel Mnk1/2 inhibitors.
• The identified interactions, particularly with hydrophobic residues in the active site, explain the inhibitory mechanism of these small molecules.
• These findings support the potential of imidazopyridine and imidazopyrazine derivatives as anticancer therapeutics targeting the Mnk-eIF4E pathway.