Dissecting protein-protein interactions in proteasome assembly: Implication to its self-assembly

Area of Science:

• Proteasome structure and function
• Molecular and cellular biology
• Protein-protein interactions

Background:

• The 26S proteasome maintains cellular homeostasis by degrading damaged proteins.
• It comprises a 20S core particle (CP) and 19S regulatory particles.
• The 20S CP is formed by stacked alpha and beta subunits.

Purpose of the Study:

• To understand the structure-function relationship of the 20S proteasome core particle.
• To analyze the structural and physiochemical properties of protein-protein interfaces within the 20S CP.
• To investigate the evolutionary conservation of the 20S CP.

Main Methods:

• Dissection of protein-protein interfaces within the 20S proteasome core particle.
• Analysis of structural and physiochemical properties (size, hydrophobicity, polarity, salt-bridge density).
• Comparative analysis of evolutionary conservation across alpha and beta subunits and different domains of life.

Main Results:

• Intra-alpha interfaces are larger and more hydrophobic; inter-beta interfaces are well-packed, polar, and have high salt-bridge density.
• Beta subunit residues are more conserved than alpha subunits during proteasome assembly; multi-interface residues are the most conserved.
• Eukaryotic proteasome interfaces are larger and better packed than archaeal and bacterial ones.

Conclusions:

• Structural and physiochemical properties of interfaces dictate 20S proteasome assembly.
• Glycine is a highly conserved residue at alpha and beta subunit interfaces.
• Findings provide a structural basis for 20S core particle assembly across all domains of life.