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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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Proteasomes tether to two distinct sites at the nuclear pore complex
Sahradha Albert1, Miroslava Schaffer1, Florian Beck1
1Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany.
Summary
Nuclear proteasomes (26S) monitor the nuclear pore complex (NPC) in Chlamydomonas reinhardtii. These proteasomes are tethered to the NPC, suggesting a role in regulating nuclear transport and protein quality control.
Area of Science:
- Cell Biology
- Molecular Biology
- Structural Biology
Background:
- Eukaryotic cells separate nuclear and cytoplasmic components.
- The nuclear pore complex (NPC) regulates macromolecule transport.
- The existence of surveillance mechanisms reinforcing NPC function is unknown.
Purpose of the Study:
- Investigate potential surveillance mechanisms at the NPC.
- Determine the localization and function of nuclear proteasomes.
- Understand the role of proteasomes in nuclear transport and quality control.
Main Methods:
- In situ cryo-electron tomography of Chlamydomonas reinhardtii.
- Subtomogram averaging.
- Nanometer-precision localization.
Main Results:
- Nuclear 26S proteasomes were observed surrounding NPCs.
- Two classes of proteasomes were identified: basket-tethered and membrane-tethered.
- Proteasomes bind to NPC basket sites and inner nuclear membrane sites via Rpn9 subunits.
Conclusions:
- Nuclear proteasomes are strategically positioned at NPCs.
- These proteasomes may regulate transcription and protein quality control.
- The findings reveal a novel surveillance mechanism at the nuclear envelope.
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