Structural insights into subtype-specific agonist recognition by sphingosine-1-phosphate receptors

Area of Science:

• Structural biology
• Pharmacology
• Biochemistry

Background:

• Sphingosine-1-phosphate (S1P) is a critical sphingolipid metabolite regulating physiological and pathological processes.
• S1P exerts its functions by activating five G protein-coupled sphingosine-1-phosphate receptors (S1PR1-5).

Purpose of the Study:

• To elucidate the molecular determinants governing agonist selectivity for S1PR1 over other S1PR subtypes.
• To provide a structural basis for designing highly selective S1PR1 agonists for therapeutic development.

Main Methods:

• Cryo-electron microscopy (cryo-EM) to determine structures of agonist-bound S1PR1-Gi1 complexes.
• Molecular dynamics (MD) simulations to analyze binding interactions and dynamics.
• Pharmacological assays to validate selectivity profiles.

Main Results:

• Identified nonconserved residues and distinct agonist binding orientations contributing to S1PR1 selectivity.
• Demonstrated how steric clashes and restricted insertion into binding pockets of S1PR3 and S1PR5 enhance S1PR1 selectivity.
• Revealed that bulky side chains in S1PR2 and S1PR4 pockets hinder binding of broad-width agonists.

Conclusions:

• Established a structural framework for understanding S1PR1 agonist selectivity.
• Findings facilitate the rational design of next-generation, highly selective S1PR1 agonists with enhanced therapeutic potential.