Rational design of a Kappa opioid receptor peptide agonist with attenuated β-arrestin signaling
- Huanhuan Zhang
- Ruolan Wang
- Pan Shi
- Gaoming Wang
- Qingjun Zhu
- Xinheng He
- Youwei Xu
- Qingning Yuan
- Wen Hu
- Kai Wu
- Yong Zheng
- Li Zhou
- Jun Liang
- Pei Lv
- Ziyan Xu
- Fan Yang
- Yingbin Liu
- Youwen Zhuang
- H. Eric Xu
- Yue Wang
- Changlin Tian
2026-04-14
Difelikefalin is an FDA-approved κ-opioid receptor (KOR) peptide agonist used to treat chronic pruritus. However, as a balanced agonist that activates both G protein and β-arrestin pathways, difelikefalin remains associated with undesirable side effects linked to β-arrestin signaling. Here, we report the cryo-EM structure of the difelikefalin-KOR-Gi complex, identifying Y320 7.43 as a key residue that is critical for signaling bias. Guided by this structural insight, we engineer beta01, a β-amino acid-substituted analog with potent G protein activation but minimal β-arrestin recruitment. In mouse models, beta01 retains robust antinociceptive and antipruritic efficacy while significantly reducing sedation and anxiety-like behaviors. Structural, molecular dynamics simulations and 2D 13 C-Met NMR analyses further reveal beta01 stabilizes a unique KOR conformation with an expanded intracellular cavity that disfavors β-arrestin binding. This work establishes a rational structure-based framework for designing safer and more effective GPCR-targeted therapeutics.