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Updated: Mar 8, 2026
09:57
Examining Proteasome Assembly with Recombinant Archaeal Proteasomes and Nondenaturing PAGE: The Case for a Combined Approach
Published on: December 17, 2016
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Nucleotide-dependent switch in proteasome assembly mediated by the Nas6 chaperone
Frances Li1, Geng Tian2, Deanna Langager1
1Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, CO 80309.
Summary
The Nas6 chaperone controls proteasome assembly by switching its inhibitory role based on ATP hydrolysis. It blocks lid or core particle interaction, ensuring proper proteasome formation.
Area of Science:
- Cellular biology
- Molecular biology
- Biochemistry
Background:
- The proteasome is a large protein complex essential for cellular protein degradation.
- Proteasome assembly involves the precise interaction of multiple subunits, including the lid, base, and core particle (CP).
- Chaperones like Rpn14, Nas6, Hsm3, and Nas2 regulate proteasome assembly by interacting with the base subunit.
Purpose of the Study:
- To investigate the dual role of the Nas6 chaperone in proteasome assembly.
- To elucidate the mechanism by which Nas6 controls interactions between proteasome subunits.
- To understand how Nas6's function is modulated by the nucleotide state of the proteasome base.
Main Methods:
- Cryoelectron microscopy (cryo-EM) to visualize proteasome structures.
- Structural modeling to analyze chaperone-subunit interactions.
- Biochemical assays to assess chaperone binding and assembly inhibition.
Main Results:
- Nas6 antagonizes both base-core particle (CP) and base-lid interactions during proteasome assembly.
- Nas6's inhibitory mode is dependent on the nucleotide state of the proteasome base.
- Nas6 blocks base-lid association when ATP hydrolysis is inhibited, and base-CP association when ATP is hydrolyzed.
- Structural modeling reveals Nas6 sterically hinders interactions with either the lid or CP based on the nucleotide state.
Conclusions:
- Nas6 acts as a crucial regulator of proteasome assembly through a dual inhibitory mechanism.
- Nas6's nucleotide-dependent function ensures the correct order of subunit association.
- This study provides insights into the intricate process of proteasome biogenesis and regulation.
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