Molecular mechanisms of fentanyl mediated β-arrestin biased signaling

PLoS Comput Biol. 2020 Apr 10;16(4):e1007394. doi: 10.1371/journal.pcbi.1007394. eCollection 2020 Apr.


The development of novel analgesics with improved safety profiles to combat the opioid epidemic represents a central question to G protein coupled receptor structural biology and pharmacology: What chemical features dictate G protein or β-arrestin signaling? Here we use adaptively biased molecular dynamics simulations to determine how fentanyl, a potent β-arrestin biased agonist, binds the μ-opioid receptor (μOR). The resulting fentanyl-bound pose provides rational insight into a wealth of historical structure-activity-relationship on its chemical scaffold. Following an in-silico derived hypothesis we found that fentanyl and the synthetic opioid peptide DAMGO require M153 to induce β-arrestin coupling, while M153 was dispensable for G protein coupling. We propose and validate an activation mechanism where the n-aniline ring of fentanyl mediates μOR β-arrestin through a novel M153 "microswitch" by synthesizing fentanyl-based derivatives that exhibit complete, clinically desirable, G protein biased coupling. Together, these results provide molecular insight into fentanyl mediated β-arrestin biased signaling and a rational framework for further optimization of fentanyl-based analgesics with improved safety profiles.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Analgesics, Opioid / chemistry
  • Analgesics, Opioid / pharmacology
  • Fentanyl / metabolism
  • Fentanyl / pharmacology*
  • GTP-Binding Proteins / metabolism
  • Humans
  • Molecular Dynamics Simulation
  • Receptors, G-Protein-Coupled / metabolism
  • Receptors, Opioid, mu / chemistry
  • Receptors, Opioid, mu / metabolism
  • Signal Transduction / drug effects
  • Structure-Activity Relationship
  • beta-Arrestins / agonists
  • beta-Arrestins / metabolism*
  • beta-Arrestins / ultrastructure*


  • Analgesics, Opioid
  • Receptors, G-Protein-Coupled
  • Receptors, Opioid, mu
  • beta-Arrestins
  • GTP-Binding Proteins
  • Fentanyl

Grant support

This work is in part supported by the Van Andel Institute Graduate School (PWdW), the Jay and Betty Van Andel Foundation (KM, BMD, and HEX), and the National Natural Science Foundation (31770796 to YJ), the National Science and Technology Major Project (2018ZX09711002 to YJ); the K.C. Wong Education Foundation (YJ). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.