Functional profiling of asymmetrically-organized human CCT/TRiC chaperonin

Area of Science:

• Molecular Biology
• Structural Biology
• Biochemistry

Background:

• The eukaryotic chaperonin CCT/TRiC complex is essential for folding specific client proteins, including tubulin and actin.
• Its eight distinct subunits form a unique folding cavity with polarized inner faces, suggesting functional asymmetry.

Purpose of the Study:

• To structurally characterize the closed and open states of the CCT complex using molecular dynamics.
• To investigate the role of inter-subunit interactions and redox properties in CCT complex function.

Main Methods:

• Molecular dynamics simulations to analyze CCT complex conformational changes.
• Analysis of inter-subunit interaction energies and redox-related surface properties.
• Experimental verification of cysteine activation events using tubulin as a model substrate.

Main Results:

• Asymmetric distribution and remodeling of inter-subunit interaction energies during conformational changes.
• Significant alterations in inner surface properties, including electrostatic potential and cysteine exposure, between closed and open states.
• Experimental validation of cysteine activation, crucial for substrate interaction.

Conclusions:

• The study highlights the dynamic nature of the CCT/TRiC complex and its polarized structure.
• Redox-dependent changes in surface properties are critical for chaperonin function.
• Dynamics-based structural profiling is essential for understanding asymmetric chaperonin mechanisms.