Harnessing AlphaFold3 to elucidate BBSome structure and protein partners

Area of Science:

• Structural biology
• Molecular medicine
• Cell biology

Background:

• The BBSome is an eight-protein complex vital for ciliary function and implicated in Bardet-Biedl syndrome (BBS).
• While its structure and interactions are partially understood, its role in cargo recognition and complex dynamics requires further investigation.

Purpose of the Study:

• To elucidate the structural organization and dynamics of the BBSome complex.
• To identify BBSome interactions with G protein-coupled receptors (GPCRs) and metabolic signaling proteins.
• To investigate the impact of pathogenic mutations on BBSome stability.

Main Methods:

• Structural modeling using AlphaFold3, validated against cryo-EM data.
• Interface residue analysis to identify key interaction hubs within the BBSome.
• Computational prediction and experimental validation (immunoprecipitation, peptide competition assays) of BBSome-receptor interactions.

Main Results:

• AlphaFold3 generated a high-accuracy structural model of the BBSome.
• BBS1 and BBS9 were identified as central interaction hubs; BBS2 and BBS7 showed significant polar contacts.
• The BBS1^M390R mutation was predicted to destabilize the complex.
• BBSome interactions with GPCRs and metabolic receptors (MRAP2, leptin, insulin receptors) were predicted and supported by experimental data.
• BBS4 interaction with pericentriolar material 1 suggests a role in centriolar satellite localization.

Conclusions:

• The study provides a detailed structural and interaction framework for the BBSome.
• Findings offer insights into BBS pathogenesis and the BBSome's role in ciliary trafficking and metabolic signaling.
• The predictive modeling approach serves as a valuable tool for future research into BBS and related ciliopathies.