Structural and dynamic insights into the biased signaling mechanism of the human kappa opioid receptor

The κ-opioid receptor (KOR) is a member of the G protein-coupled receptor (GPCR) family, modulating cellular responses through transducers such as G proteins and β-arrestins. G-protein-biased KOR agonists aim to retain analgesic and antipruritic actions while limiting aversion and sedation. Aiming to inform G-biased KOR agonist design, we analyze signaling-relevant residues from structural and dynamic views. Here we show, using multiple complementary methods, shared residues that determine β-arrestin recruitment by nalfurafine and U-50,488H. Cryo-electron microscopy structures of the KOR-G<sub>i</sub> signaling complexes identify the ligand binding mode in the activated state. Vibrational spectroscopy reveals ligand-induced conformational changes. Cell-based mutant experiments pinpoint four amino acids (K227<sup>5.40</sup>, C286<sup>6.47</sup>, H291<sup>6.52</sup>, and Y312<sup>7.34</sup>; Ballesteros-Weinstein numbering is shown in superscript) that play crucial roles in β-arrestin recruitment. Furthermore, MD simulations revealed that the four mutants tend to adopt conformations with reduced β-arrestin recruitment activity. Our research findings provide a foundation for enhancing KOR-mediated therapeutic effects while minimizing unwanted side effects by targeting specific residues within the KOR ligand-binding pocket, including K227<sup>5.40</sup> and Y312<sup>7.34</sup>, which have previously been implicated in biased signaling.

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Publication Details

Journal
Nature Communications
Published
2025-10-28
DOI
https://doi.org/10.1038/s41467-025-64882-1
Primary Topic
Receptor Mechanisms and Signaling
Type
article
Field-Weighted Citation Impact
0.00

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article

Structural and dynamic insights into the biased signaling mechanism of the human kappa opioid receptor

Ryo Nishikawa, Akihisa Tokuda, Shun Yokoi, Hideki Kandori et al.
Nature Communications
Receptor Mechanisms and Signaling
article

Structural and dynamic insights into the biased signaling mechanism of the human kappa opioid receptor

Ryo Nishikawa, Akihisa Tokuda, Shun Yokoi, Hideki Kandori, Hiroshi Nagase, Mika Hirose, Ayori Mitsutake, Ryoji Kise, Chiyo Suno-Ikeda, Tomoyo Takai, Asuka Inoue, Takayuki Kato, Ryoji Suno, Yukihiko Sugita, Kota Katayama, Seiya Iwata, Eri Asai, Takuya Kobayashi, Akitoshi Inoue, Tsuyoshi Saitoh, Takaya Ogura, Riko Suzuki, Risako Katamoto
article en

Abstract

The κ-opioid receptor (KOR) is a member of the G protein-coupled receptor (GPCR) family, modulating cellular responses through transducers such as G proteins and β-arrestins. G-protein-biased KOR agonists aim to retain analgesic and antipruritic actions while limiting aversion and sedation. Aiming to inform G-biased KOR agonist design, we analyze signaling-relevant residues from structural and dynamic views. Here we show, using multiple complementary methods, shared residues that determine β-arrestin recruitment by nalfurafine and U-50,488H. Cryo-electron microscopy structures of the KOR-G<sub>i</sub> signaling complexes identify the ligand binding mode in the activated state. Vibrational spectroscopy reveals ligand-induced conformational changes. Cell-based mutant experiments pinpoint four amino acids (K227<sup>5.40</sup>, C286<sup>6.47</sup>, H291<sup>6.52</sup>, and Y312<sup>7.34</sup>; Ballesteros-Weinstein numbering is shown in superscript) that play crucial roles in β-arrestin recruitment. Furthermore, MD simulations revealed that the four mutants tend to adopt conformations with reduced β-arrestin recruitment activity. Our research findings provide a foundation for enhancing KOR-mediated therapeutic effects while minimizing unwanted side effects by targeting specific residues within the KOR ligand-binding pocket, including K227<sup>5.40</sup> and Y312<sup>7.34</sup>, which have previously been implicated in biased signaling.

Nature CommunicationsVol. 16(1)
Kansai Medical University (JP), University of Tsukuba (JP), Meiji University (JP), Nagoya Institute of Technology (JP), Tohoku University (JP), Kyoto University (JP), Kyoto Pharmaceutical University (JP), Japan Agency for Medical Research and Development (JP), Protein Research Foundation (JP), The University of Osaka (JP), Tsukuba International University (JP)
Japan Foundation for Applied Enzymology, Japan Agency for Medical Research and Development, Meiji University, Ministry of Education, Culture, Sports, Science and Technology, University of Tsukuba, Kansai Medical University, Japan Society for the Promotion of Science, Core Research for Evolutional Science and Technology, JST-Mirai Program, Moonshot Research and Development Program
Openalex Percentile: Top 72%
Receptor Mechanisms and Signaling
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