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Structure and function of a near fully-activated intermediate GPCR-Gαβγ complex
Maxine Bi1, Xudong Wang2, Jinan Wang3
1Department of Biochemistry and Biophysics, University of California, 600 16th Street, San Francisco, CA, 94143, USA.
Nature Communications
|January 28, 2025
Summary
Researchers captured the structure of an intermediate G protein-coupled receptor (GPCR)-Gαβγ complex, revealing its role in initiating nucleotide exchange for drug development.
Area of Science:
- Biochemistry
- Structural Biology
- Pharmacology
Background:
- Understanding G protein-coupled receptor (GPCR) intermediate complexes is crucial for drug development.
- Existing structural data predominantly shows fully activated GPCR-Gαβγ complexes, leaving intermediate states poorly understood.
Purpose of the Study:
- To determine the structure of an intermediate GPCR-Gαsβγ complex.
- To elucidate the functional role of this intermediate complex in GPCR signaling.
Main Methods:
- Cryo-electron microscopy (cryo-EM) at 2.6 Å resolution.
- 19F quantitative NMR and molecular dynamics (MD) simulations to guide structural determination.
- BODIPY-GDP/GTP based nucleotide exchange assays.
Main Results:
- The structure of an intermediate GPCR-mini-Gαsβγ complex was determined by inhibiting its transition to the fully activated state.
- Direct evidence shows this intermediate complex initiates a rate-limited nucleotide exchange.
- The Gα subunit's α-helical domain is partially open, binding nucleotides at a non-canonical site.
Conclusions:
- This study provides the first structural and functional insights into an intermediate GPCR-Gαsβγ complex.
- The findings reveal a novel mechanism for nucleotide binding and exchange, bridging a gap in GPCR signaling knowledge.
- This work has implications for the rational design of drugs targeting GPCR pathways.
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