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A highly conserved δ‐opioid receptor region determines RGS4 interaction
Author(s) -
Karoussiotis Christos,
MartiSolano Maria,
Stepniewski Tomasz Maciej,
Symeonof Alexandra,
Selent Jana,
Georgoussi Zafiroula
Publication year - 2020
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/febs.15033
Subject(s) - opioid receptor , opioid , computational biology , biology , receptor , genetics
The δ‐opioid receptor (δ‐OR) couples to Gi/Go proteins to modulate a variety of responses in the nervous system. Τhe regulator of G protein signalling 4 (RGS4) was previously shown to directly interact within the C‐terminal region of δ‐OR using its N‐terminal domain to negatively modulate opioid receptor signalling. Herein, using molecular dynamics simulations and in vitro pull‐down experiments we delimit this interaction to 12 helix 8 residues of δ‐ΟR and to the first 17 N‐terminal residues (NT) of RGS4. Monitoring the complex arrangement and stabilization between RGS4 and δ‐OR by molecular dynamics simulations combined with mutagenesis studies, we defined that two critical interactions are formed: one between Phe329 of helix8 of δ‐ΟR and Pro9 of the NT of RGS4 and the other a salt bridge between Glu323 of δ‐ΟR and Lys17 of RGS4. Our observations allow drafting for the first time a structural model of a ternary complex including the δ‐opioid receptor, a G protein and a RGS protein. Furthermore, the high degree of conservation among opioid receptors of the RGS4‐binding region, points to a conserved interaction mode between opioid receptors and this important regulatory protein.