Crystal Structure of CC Chemokine Receptor 2A in Complex with an Orthosteric Antagonist Provides Insights for the Design of Selective Antagonists

We determined two crystal structures of the chemokine receptor CCR2A in complex with the orthosteric antagonist MK-0812. Full-length CCR2A, stabilized by rubredoxin and a series of five mutations were resolved at 3.3 Å. An N- and C-terminally truncated CCR2A construct was crystallized in an alternate crystal form, which yielded a 2.7 Å resolution structure using serial synchrotron crystallography. Our structures provide a clear structural explanation for the observed key role of residue E2917.39 in high-affinity binding of several orthosteric CCR2 antagonists. By combining all the structural information collected, we generated models of co-structures for the structurally diverse pyrimidine amide class of CCR2 antagonists. Even though the representative Ex15 overlays well with MK-0812, it also interacts with the non-conserved H1213.33, resulting in a significant selectivity over CCR5. Insights derived from this work will facilitate drug discovery efforts directed toward highly selective CCR2 antagonists with potentially superior efficacy. [Display omitted] •Two CCR2A structures in complex with the orthosteric antagonist MK-0812 were solved•IMISX in situ plates facilitated high-quality diffraction data collection•Residue E2917.39 was confirmed as important in orthosteric antagonist binding•The non-conserved residue H1213.33 is important for CCR2 selectivity over CCR5 Two independent structures of CCR2A in complex with the orthosteric antagonist MK-0812 were solved, confirming the importance of residue E2917.39 for antagonist binding. Structural modeling of pyrimidine amide antagonists showed an interaction with the non-conserved H1213.33, leading to a significant selectivity over CCR5, suggesting strategies for highly selective CCR2 antagonist design.