Structure-based Evolution of G protein-biased μ-opioid Receptor Agonists
The -opioid receptor (OR) is the major target for opioid analgesics. Activation of OR initiates signaling through G protein pathways as well as through {beta}-arrestin recruitment. OR agonists that are biased towards G protein signaling pathways demonstrate diminished side effects. PZM21, discovered by computational docking, is a G protein biased OR agonist. Here we report the cryoEM structure of PZM21 bound OR in complex with Gi protein. Structure-based evolution led to multiple PZM21 analogs with more pronounced Gi protein bias and increased lipophilicity to improve CNS penetration. Among them, FH210 shows extremely low potency and efficacy for arrestin recruitment. We further determined the cryoEM structure of FH210 bound to OR in complex with Gi protein and confirmed its expected binding pose. The structural and pharmacological studies reveal a potential mechanism to reduce {beta}-arrestin recruitment by the OR, and hold promise for developing next-generation analgesics with fewer adverse effects. Table of Contents Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=43 SRC="FIGDIR/small/485330v1_ufig1.gif" ALT="Figure 1"> View larger version (14K): org.highwire.dtl.DTLVardef@125808corg.highwire.dtl.DTLVardef@11aa15corg.highwire.dtl.DTLVardef@157caaaorg.highwire.dtl.DTLVardef@ba837d_HPS_FORMAT_FIGEXP M_FIG C_FIG We obtained cryoEM structures of the -opioid receptor (OR) bound to the lead compound PZM21 and the newly developed agonist FH210 to understand the mechanism of their biased signaling and to guide the evolution of next-generation analgesics with fewer adverse effects.