Structural insights into the human P2X1 receptor and ligand interactions.

Area of Science:

• Biochemistry and Structural Biology
• Pharmacology
• Molecular Medicine

Background:

• The P2X1 receptor, a trimeric ligand-gated ion channel, is crucial for urogenital and immune functions.
• Limited structural data and tool compounds have impeded P2X1 receptor drug development.

Purpose of the Study:

• To determine the structures of the P2X1 receptor in ATP-bound (desensitized) and NF449-bound (closed) states using cryo-EM.
• To investigate the molecular basis of P2X1 receptor activation, inhibition, and ligand interactions through site-directed mutagenesis.

Main Methods:

• Cryogenic electron microscopy (cryo-EM) for structural elucidation.
• Site-directed mutagenesis of key residues involved in ligand and metal ion binding.
• Radioligand binding assays and intracellular calcium ion influx assays to assess mutation effects.

Main Results:

• Elucidation of P2X1 receptor structures in ATP-bound desensitized and NF449-bound closed states.
• Distinct binding modes of the antagonist NF449 compared to the endogenous ligand ATP.
• Identification of critical conserved and non-conserved residues for ligand binding and receptor modulation.

Conclusions:

• This study provides high-resolution structures of the P2X1 receptor, enhancing understanding of its function.
• Key molecular interactions governing P2X1 receptor activity have been identified.
• The findings pave the way for structure-based in silico drug design targeting the P2X1 receptor for therapeutic interventions.