Binding mode of cyclic chemerin‐9 peptide and chemerinS157 protein at CMKLR

The chemokine‐like receptor 1 (CMKLR1) is activated by the adipokine and chemoattractant protein chemerin. Cryo‐EM structures of chemerin‐9‐CMKLR1‐Gi have been published, where chemerin‐9 is the nonapeptide of the C terminus of chemerinS157. Chemerin‐9 is as active as the full‐length protein in Ca2+‐release but shows differences in equilibrium read‐outs. An equally potent cyclic chemerin‐9 variant (cC9) was reported previously. Now, we have built a computational model of CMKLR1 to investigate the binding mode of cC9 and chemerinS157 in comparison to chemerin‐9. Differences were investigated using CMKLR1 variants. Double‐mutant cycle analysis identified CMKLR1‐F2.53 as the relevant position for Phe8‐binding of cC9. Energy contribution revealed slight differences in Phe8‐binding to CMKLR1‐F2.53 and space for larger residues. This was confirmed as the chemerin‐9 variant with 1‐naphthyl‐L‐alanine at position 8 showed a 4‐fold increased potency of 2 nM (pEC50=8.6±0.15). While chemerin‐9 and cC9 share their interactions at the CMKLR1, chemerinS157 tolerates most mutations of CMKLR1 in the deep binding site. The computational model of chemerinS157 suggests a β‐sheet interaction between the N‐terminal CMKLR1‐segment I25VVL28 and the β‐sheet D108KVLGRLVH116 of ChemS157, which was confirmed experimentally. Our data expand the knowledge by identifying the binding mode of chemerinS157 and cC9 at CMKLR1 facilitating future structure‐based drug design.