αα-Hub domains and intrinsically disordered proteins: A decisive combo

Area of Science:

• Structural biology
• Molecular biology
• Biochemistry

Background:

• Hub proteins are central to protein-protein interaction networks.
• A new class of folded hubs, αα-hubs, share an αα-hairpin supersecondary structure.
• These hubs are found in large proteins involved in human diseases and plant quality.

Purpose of the Study:

• To provide a unified description of αα-hubs by comparing their structures, functions, and complexes.
• To expand molecular concepts related to protein-protein interactions and signal fidelity.
• To propose new research questions based on αα-hub properties.

Main Methods:

• Review and comparative analysis of existing studies on αα-hub structures, functions, and complexes.
• Integration of findings across different αα-hub members (PAH, RST, TAFH, NCBD, HHD).
• Conceptual expansion of protein-protein interaction principles.

Main Results:

• Identified shared structural and functional properties of αα-hubs.
• Introduced new concepts: context, motif reversibility, multivalency, complex heterogeneity, synergistic folding, accessory binding sites, and supramodules.
• Highlighted αα-hub fold characteristics (supersite properties, dynamics, malleability) and disordered ligand adaptability contributing to signal fidelity and specificity.

Conclusions:

• αα-hubs possess multifaceted properties enabling complex protein interactions and signal fidelity.
• These hubs, with their adaptable disordered ligands, serve as ideal models for studying signal specificity.
• The review opens avenues for new research into the collective properties and functions of αα-hubs.