Scribble co-operatively binds multiple α_1D-adrenergic receptor C-terminal PDZ ligands

Area of Science:

• Molecular and Cellular Biology
• Pharmacology
• Structural Biology

Background:

• G protein-coupled receptors (GPCRs) form dynamic macromolecular complexes.
• Alpha1D-adrenergic receptors (α1D-ARs) regulate cardiovascular and central nervous system functions.
• Understanding GPCR complex structure can reveal drug development targets.

Purpose of the Study:

• To map the structural determinants of α1D-AR complex architecture.
• To identify specific protein-protein interfaces for drug development.
• To investigate the binding interaction between α1D-AR and the PDZ protein scribble (SCRIB).

Main Methods:

• Biolayer interferometry (BLI) to measure binding affinity.
• In situ and in vitro assays to identify interaction sites.
• SNAP-GST pull-down assays to analyze binding mechanisms.
• Structure-function analyses and crystal structure determination.

Main Results:

• α1D-AR PDZ ligand selectively binds SCRIB with >8x higher affinity than other interactors.
• SCRIB PDZ domains 1 and 4 are high-affinity interaction sites for the α1D-AR PDZ ligand.
• SCRIB binds α1D-AR PDZ ligands via a co-operative mechanism.
• Residue R1110PDZ4 is critical for SCRIB:α1D-AR binding specificity, with structural shifts in the binding loop.

Conclusions:

• SCRIB PDZ domains 1 and 4 are high-affinity binding sites for α1D-AR.
• The identified SCRIB:α1D-AR interaction represents a potential drug target.
• Targeting this interaction may treat diseases linked to aberrant α1D-AR signaling.