A dynamic structural framework for the allosteric regulation of Hsp70 chaperones

Area of Science:

• Molecular Biology
• Structural Biology
• Biochemistry

Background:

• Heat shock protein 70 (Hsp70) chaperones are crucial ATP-driven molecular machines.
• Hsp70s utilize complex allosteric mechanisms for their functions.
• The spatiotemporal organization of Hsp70 allosteric signaling remains poorly understood.

Purpose of the Study:

• To elucidate the structural and dynamic basis of allosteric signaling pathways in Hsp70 DnaK.
• To rationalize the effects of ATP, its analogues, and client proteins on signal transmission.
• To develop a dynamic structural framework for Hsp70 allosteric regulation.

Main Methods:

• Structural and dynamic analyses of the Hsp70 DnaK model.
• Investigation of ATP, ATP analogue, and client binding effects.
• Amino acid substitution studies to probe allosteric regulation.

Main Results:

• DnaK tolerates alterations in ATP's α-phosphate but not γ-phosphate during initial sensing.
• Mutations disrupting allosteric regulation impair ATP-induced signal transmission by altering allosteric mechanics or intermediate stability.
• Client binding to a non-responsive DnaK variant shows reduced conformational changes, indicating client-induced remodeling is necessary for ATP hydrolysis.

Conclusions:

• A dynamic structural framework for Hsp70 allosteric regulation is proposed.
• The framework links Hsp70 molecular mechanics to their biochemical properties.
• Understanding these mechanisms is key to Hsp70 function in cellular processes.