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Updated: Jun 5, 2025
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Reverse Yeast Two-hybrid System to Identify Mammalian Nuclear Receptor Residues that Interact with Ligands and/or Antagonists
Published on: November 15, 2013
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Enhanced dynamic coupling in a nuclear receptor underlies ligand activity.
Tracy Yu1, Priscilla Villalona1, Sabab Hasan Khan1
1Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania, USA.
The Journal of Biological Chemistry
|December 15, 2024
Summary
Modified bile acids show enhanced potency by altering farnesoid X receptor (FXR) dynamics, specifically through a newly discovered helix 5 to helix 7 coupling mechanism, not just binding affinity.
Area of Science:
- Biochemistry
- Molecular Biology
- Pharmacology
Background:
- Bile acids are crucial signaling molecules regulating lipid and cholesterol metabolism via the farnesoid X receptor (FXR).
- Synthetic bile acid derivatives exhibit significantly higher potency than natural bile acids, but the underlying mechanisms remain unclear.
Purpose of the Study:
- To investigate the molecular mechanisms behind the enhanced potency of modified bile acid ligands for FXR.
- To elucidate the role of receptor dynamics in ligand-mediated FXR activation.
Main Methods:
- Utilized functional assays to assess ligand activity.
- Performed extensive molecular dynamics simulations (over 200 μs) to analyze receptor behavior.
- Investigated allosteric signaling pathways within the FXR protein.
Main Results:
- Experimental data contradicted the hypothesis that increased binding affinity alone explains enhanced ligand potency.
- Identified an unexpected, crucial role for helix 5 in the allosteric signaling of obeticholic acid.
- Revealed a unique, enhanced dynamic coupling between helices 5 and 7 induced by bile acid modification, directly impacting FXR dynamics and ligand potency.
Conclusions:
- The enhanced potency of bile acid analogs is directly linked to their specific effects on FXR protein dynamics.
- Discovered a novel mechanism involving helix 5 to helix 7 coupling in FXR allosteric signaling.
- Highlighted the critical interplay between nuclear receptor ligand activity and receptor conformational dynamics.
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