Covalent agonists for studying G protein-coupled receptor activation

Area of Science:

• Structural biology
• Pharmacology
• Biochemistry

Background:

• G protein-coupled receptors (GPCRs) are critical drug targets, but their structural studies, especially in active states, are challenging.
• Stabilizing active GPCR conformations for crystallization requires high-affinity ligands, which native hormones often lack.

Purpose of the Study:

• To develop novel molecular tools for stabilizing active aminergic GPCRs for structural studies.
• To create covalent agonists derived from monoamine neurotransmitters for Gs-, Gi-, and Gq-coupled receptors.

Main Methods:

• Developed a versatile synthetic strategy to create covalent agonists from noradrenaline, dopamine, serotonin, and histamine.
• Validated covalent binding and G protein activation of the tool compounds.
• Determined the crystal structure of the β2-adrenoreceptor complexed with a covalent noradrenaline analog and a nanobody.

Main Results:

• Successfully synthesized and characterized covalent agonists with efficient binding modes.
• Covalent ligand-receptor complexes activated G proteins similarly to natural neurotransmitters.
• The crystal structure confirmed the utility of these covalent agonists in facilitating GPCR crystallogenesis.

Conclusions:

• Novel covalent agonists provide a powerful strategy for stabilizing active aminergic GPCR states.
• These tools are effective for structural biology and can advance the understanding and drug development of GPCRs.