The molecular chaperone Hsp104--a molecular machine for protein disaggregation

Area of Science:

• Molecular biology
• Protein biochemistry
• Cellular stress response

Background:

• Protein aggregation was historically considered irreversible.
• The discovery of Hsp104's ability to dissolve aggregates was initially met with skepticism.
• Hsp104 is a crucial molecular chaperone in yeast.

Purpose of the Study:

• To investigate the function of the yeast molecular chaperone Hsp104.
• To understand the mechanism by which Hsp104 disassembles protein aggregates.
• To explore the role of Hsp104 in cellular processes like prion maintenance.

Main Methods:

• Investigating Hsp104's interaction with Hsp70 and Hsp40.
• Studying the ATP-dependent activity of Hsp104.
• Identifying and characterizing Hsp104 homologues in various organisms.

Main Results:

• Hsp104, with Hsp70 and Hsp40, actively disassembles protein aggregates and facilitates refolding.
• Homologues of Hsp104 (ClpB, Hsp78, Hsp101) exist in bacteria, mitochondria, and plants, but not animal cell cytosols.
• Hsp104 is essential for maintaining yeast prions.

Conclusions:

• Hsp104 represents a novel class of ATP-dependent molecular machines capable of reversing protein aggregation.
• The absence of Hsp104 homologues in animal cell cytosols warrants further investigation.
• Understanding Hsp104's mechanism provides insights into protein quality control and prion biology.