Structural basis for chemokine recognition and receptor activation of chemokine receptor CCR5

Hui Zhang,Qiang Shao,Qiuxiang Tan,Xiaojing Chu,Shuo Han,Chenhui Zhang,Kun Chen,Ya Zhu,Qiang Zhao,Beili Wu,Cuiying Yi,Yechun Xu

doi:10.1038/s41467-021-24438-5

Abstract

The chemokine receptor CCR5 plays a vital role in immune surveillance and inflammation. However, molecular details that govern its endogenous chemokine recognition and receptor activation remain elusive. Here we report three cryo-electron microscopy structures of Gi1 protein-coupled CCR5 in a ligand-free state and in complex with the chemokine MIP-1α or RANTES, as well as the crystal structure of MIP-1α-bound CCR5. These structures reveal distinct binding modes of the two chemokines and a specific accommodate pattern of the chemokine for the distal N terminus of CCR5. Together with functional data, the structures demonstrate that chemokine-induced rearrangement of toggle switch and plasticity of the receptor extracellular region are critical for receptor activation, while a conserved tryptophan residue in helix II acts as a trigger of receptor constitutive activation.

Highlights

The chemokine receptor CCR5 plays a vital role in immune surveillance and inflammation
We report three cryo-electron microscopy (cryo-EM) structures of CCR5 bound to heterotrimeric Gi1 protein in both ligand-free and chemokine (MIP-1α or RANTES)-bound states as well as the crystal structure of CCR5 in complex with MIP-1α
For structure determination of the ligand-free CCR5–Gi1 complex, a mutation G1634.60N [superscript indicates Ballesteros–Weinstein nomenclature17] was introduced in the wild-type CCR5 and 33 residues (F320-L352) were truncated at the receptor C terminus to improve protein yield and homogeneity as previously reported[16] (Supplementary Fig. 1a, b). The effect of these modifications on receptor function was assessed by a Cyclic AMP (cAMP) inhibition assay and an inositol phosphate (IP) accumulation assay using a chimeric Gα protein GαΔ6qi4myr, which converts Gi-related signaling into a Gq readout[18]

Summary

Introduction

The chemokine receptor CCR5 plays a vital role in immune surveillance and inflammation. For structure determination of the ligand-free CCR5–Gi1 complex, a mutation G1634.60N [superscript indicates Ballesteros–Weinstein nomenclature17] was introduced in the wild-type CCR5 and 33 residues (F320-L352) were truncated at the receptor C terminus to improve protein yield and homogeneity as previously reported[16] (Supplementary Fig. 1a, b).

Results

Conclusion