Mechanistic Insights into Hsp104 Potentiation

Area of Science:

• Protein biochemistry
• Neurodegenerative disease research
• Molecular mechanisms of protein aggregation

Background:

• Protein aggregates are hallmarks of neurodegenerative diseases like Parkinson disease and ALS.
• Hsp104, a yeast protein disaggregase, can dissolve these aggregates but its potentiation mechanisms are unclear.
• Targeting protein aggregation is a key strategy for treating neurodegenerative disorders.

Purpose of the Study:

• To elucidate the molecular mechanisms underlying Hsp104 potentiation.
• To define the ATPase and substrate-binding requirements for potentiated Hsp104 activity.
• To explore the therapeutic potential of potentiated Hsp104 variants in disease models.

Main Methods:

• Site-directed mutagenesis of Hsp104 (e.g., A503V, Y257A, Y662A, T317A, N728A).
• In vitro assays measuring disaggregase activity and ATPase kinetics.
• In vivo studies using yeast models expressing disease-related proteins (TDP-43, FUS, α-synuclein).

Main Results:

• Potentiated Hsp104 activity requires 2-3 A503V mutations and is modulated by substrate binding at NBD1 and NBD2.
• Altered ATP hydrolysis patterns and inter-domain signaling are critical for potentiation.
• Mutations reducing ATPase activity (sensor-1 mutations) did not abolish potentiated activity, unlike in wild-type Hsp104.
• Potentiated Hsp104 variants rescued toxicity of TDP-43, FUS, and α-synuclein in yeast.

Conclusions:

• Hsp104 potentiation involves specific subunit mutations and altered ATPase/signaling dynamics.
• ATPase activity in either NBD1 or NBD2 is sufficient for potentiated disaggregase function.
• Potentiated Hsp104 variants demonstrate robust activity and therapeutic potential for neurodegenerative diseases.