Investigation of the Binding Site of CCR2 using 4-Azetidinyl-1-aryl-cyclohexane Derivatives: A Membrane Modeling and Molecular Dynamics Study

Chemokine receptor (CCR2) is a G protein-coupled receptor that contains seven transmembrane helices. Recent pharmaceutical research has focused on the antagonism of CCR2 and candidate drugs are currently undergoing clinical studies for the treatment of diseases like arthritis, multiple sclerosis, and type 2 diabetes. In this study, we analyzed the time dependent behavior of CCR2 docked with a potent 4-azetidinyl-1-aryl-cyclohexane (4AAC) derivative using molecular dynamics simulations (MDS) for 20 nanoseconds (ns). Homology modeling of CCR2 was performed and the 4AAC derivative was docked into this binding site. The docked model of selected conformations was then utilized to study the dynamic behavior of the 4AAC enzyme complexes inside lipid membrane. MDS of CCR2-16b of 4AAC complexes allowed us to refine the system since binding of an inhibitor to a receptor is a dynamic process and identify stable structures and better binding modes. Structure activity relationships (SAR) for 4AAC derivatives were investigated and reasons for the activities were determined. Probable binding pose for some CCR2 antagonists were determined from the perspectives of binding site. Initial modeling showed that Tyr49, Trp98, Ser101, Glu291, and additional residues are crucial for 4AAC binding, but MDS analysis showed that Ser101 may not be vital. 4AAC moved away from Ser101 and the hydrogen bonding between 4AAC and Ser101 vanished. The results of this study provide useful information regarding the structure-based drug design of CCR2 antagonists and additionally suggest key residues for further study by mutagenesis.