Conformational dynamics of the molecular chaperone Hsp90 in complexes with a co-chaperone and anticancer drugs

Area of Science:

• Molecular Biology
• Structural Biology
• Biochemistry

Background:

• The molecular chaperone Heat Shock Protein 90 (Hsp90) is vital for the proper folding, maturation, and activation of numerous client proteins.
• Many Hsp90 client proteins are involved in oncogenic processes, making Hsp90 a significant target for cancer therapy.
• Understanding Hsp90's conformational dynamics is key to developing effective anticancer strategies.

Purpose of the Study:

• To investigate the structural and conformational changes in full-length human Hsp90beta upon binding with its co-chaperone Cdc37.
• To examine the effects of Hsp90 ATPase inhibitors, Radicicol and DMAG, on Hsp90 conformation.
• To elucidate the structural basis of Hsp90's biological activity and its interactions.

Main Methods:

• Utilized hydrogen-exchange mass spectrometry (HX-MS) to monitor protein structural dynamics in solution.
• Studied full-length human Hsp90beta in its apo form and in complex with Cdc37, Radicicol, and DMAG.
• Analyzed changes in hydrogen exchange patterns to map conformational alterations across the Hsp90 structure.

Main Results:

• Observed significant hydrogen exchange changes in regions of Hsp90 distant from ligand-binding sites, indicating long-range allosteric effects.
• Identified distinct conformational differences at the interface between the N-terminal and middle domains in apo versus complexed Hsp90.
• Detected specific alterations at the middle and C-terminal domain interface upon binding of the Hsp90 inhibitors Radicicol and DMAG.

Conclusions:

• Hsp90 undergoes long-range conformational changes upon binding of co-chaperones and inhibitors, impacting its overall structure.
• The N-terminal and middle domain interface is sensitive to co-chaperone binding, suggesting a role in functional regulation.
• Inhibitor binding affects the middle and C-terminal domain interface, providing structural insights into drug action and Hsp90's active conformation.