Structural Communication between the E. coli Chaperones DnaK and Hsp90

Area of Science:

• Molecular Biology
• Biophysics
• Structural Biology

Background:

• Heat shock proteins Hsp70 (DnaK) and Hsp90 (Hsp90Ec) are crucial ATP-dependent molecular chaperones maintaining cellular homeostasis.
• These chaperones directly interact and collaborate in protein remodeling within *Escherichia coli*.

Purpose of the Study:

• To investigate the allosteric communication between Hsp90Ec and DnaK.
• To understand how these chaperones couple their conformational cycles.

Main Methods:

• Elastic Network Models (ENM)
• Normal Mode Analysis (NMA)
• Structural Perturbation Method (SPM) applied to asymmetric and symmetric DnaK-Hsp90Ec complexes.

Main Results:

• Asymmetric DnaK binding to Hsp90Ec favors motions that orient substrate proteins for Hsp90Ec binding and release from DnaK.
• A single DnaK molecule binding stabilizes the Hsp90Ec protomer.
• Symmetric DnaK binding leads to steric clashes, suggesting independent chaperone cycles.

Conclusions:

• The findings support an asymmetric binding model for DnaK to Hsp90Ec.
• This asymmetric interaction is critical for coupled chaperone function and substrate remodeling.