Tian-Xing Wu

Molecular docking and molecular dynamics simulation studies of GPR40 receptor–agonist interactions

In order to explore the agonistic activity of small-molecule agonists to GPR40, AutoDock and GROMACS software were used for docking and molecular dynamics studies. A molecular docking of eight structurally diverse agonists (six carboxylic acids (CAs) agonist, and two non-carboxylic acids (non-CAs) agonist) was performed and the differences in their binding modes were investigated. Moreover, a good linear relationship based on the predicted binding affinities (pK(i)) determined by using AutoDock and experimental activity values (pEC50) was obtained. Then, the 10ns molecular dynamics (MD) simulations of three obtained ligand-receptor complexes embedded into the phospholipid bilayer were carried out. The position fluctuations of the ligands located inside the transmembrane domain were explored, and the stable binding modes of the three studied agonists were determined. Furthermore, the residue-based decomposition of interaction energies in three systems identified several critical residues for ligand binding.

Effect of double mutations K214/A–E215/Q of FRATide on GSK3β: insights from molecular dynamics simulation and normal mode analysis

Glycogen synthase kinase 3β (GSK3β) is a multifunctional serine/threonine protein kinase that is involved in several biological processes including insulin and Wnt signaling pathways. The Wnt signaling via FRAT-mediated displacement of axin inhibits GSK3β activity toward non-primed substrates without affecting its activity toward primed substrates. Herein, molecular dynamics simulation, molecular mechanics generalized Born/surface area (MM_GBSA) calculation, and normal mode analysis are performed to explore the structural influence of the double mutations K214/A–E215/Q of FRATide on the GSK3β–FRATide complex. The results reveal that the priming phosphate-binding site, the primed substrate-binding site, the alignment of the critical active site residues in the ATP-binding site, as well as the periodic open–closed conformational change of the ATP-binding site, which are critical for the catalytic activity of GSK3β, are negligibly influenced in the mutated system compared with the wild-type (WT) system. This indicates that FRATide does not inhibit the GSK3β activity toward primed substrates. Additionally, MM_GBSA calculation indicates that the less energy-favorable GSK3β–FRATide complex is observed in the mutant than in the WT complex.

Molecular modeling and molecular dynamics simulation studies on pyrrolopyrimidine-based α-helix mimetic as dual inhibitors of MDM2 and MDMX.

Inhibition of the interactions between the tumor suppressor protein p53 and its negative regulators, the MDM2 and MDMX oncogenic proteins, is increasingly gaining interest in cancer therapy and drug design. In this study, we carry out molecular docking, molecular dynamics (MD) simulations, and molecular mechanics Poisson-Boltzmann and generalized Born/surface area (MM-PB/GBSA) binding free energy calculations on an active compound 3a and an inactive compound NC-1, which share a common pyrrolopyrimidine-based scaffold. MD simulations and MM-PB/GBSA calculations show that the compound NC-1 may not bind to MDM2 and MDMX, in agreement with the experimental results. Detailed MM-PB/GBSA calculations on the MDM2-3a and MDMX-3a complexes unravel that the binding free energies are similar for the two complexes. Furthermore, the van der Waals energy is the largest component of the binding free energy for both complexes, which indicates that the interactions between the compound 3a and MDM2 and MDMX are dominated by shape complementarity. In addition, the analysis of individual residue contribution and protein-ligand binding mode show that the three functional groups on R₁, R₂, and R₃ of the compound 3a can mimic the spatial orientation of the side chains of Phe19, Trp23, and Leu26 of p53, respectively. The obtained computational results suggest that the compound 3a can act as a dual inhibitor of MDM2-p53 and MDMX-p53 interactions, consistent with the experimental results.

Insight into analysis of interactions of GW9508 to wild-type and H86F and H137F GPR40: A combined QM/MM study and pharmacophore modeling

GPR40 is a novel potential target for the treatment of type 2 diabetes. In this work, a two-layered ONIOM based QM/MM approach was employed to study the interactions between GW9508 and GPR40: wild-type, H86F, and H137F mutated systems. The calculated results clearly indicated that His137 is directly involved in ligand recognition through the NH-π interaction with the GW9508. In contrast, His86 is not interacting with the GW9508 in the NH-π interaction. The interaction energies, calculated at the MP2/6-31(d, p) level, were performed to gain more insight into the energetic differences of the wild-type and two mutated systems at the atomistic level. In addition, the obtained pharmacophore model was well consistent with structure-functional requirements for the binding of GPR40 agonists and with per-residue energy decomposition of the ONIOM calculations.