Format

Send to

Choose Destination
Proc Natl Acad Sci U S A. 2017 Dec 26;114(52):13726-13731. doi: 10.1073/pnas.1716305114. Epub 2017 Dec 11.

Proteasomes tether to two distinct sites at the nuclear pore complex.

Author information

1
Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany.
2
Structural and Computational Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany.
3
Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany; baumeist@biochem.mpg.de engelben@biochem.mpg.de.

Abstract

The partitioning of cellular components between the nucleus and cytoplasm is the defining feature of eukaryotic life. The nuclear pore complex (NPC) selectively gates the transport of macromolecules between these compartments, but it is unknown whether surveillance mechanisms exist to reinforce this function. By leveraging in situ cryo-electron tomography to image the native cellular environment of Chlamydomonas reinhardtii, we observed that nuclear 26S proteasomes crowd around NPCs. Through a combination of subtomogram averaging and nanometer-precision localization, we identified two classes of proteasomes tethered via their Rpn9 subunits to two specific NPC locations: binding sites on the NPC basket that reflect its eightfold symmetry and more abundant binding sites at the inner nuclear membrane that encircle the NPC. These basket-tethered and membrane-tethered proteasomes, which have similar substrate-processing state frequencies as proteasomes elsewhere in the cell, are ideally positioned to regulate transcription and perform quality control of both soluble and membrane proteins transiting the NPC.

KEYWORDS:

cryo-electron tomography; focused ion beam; nuclear pore complex; proteasome; quality control

PMID:
29229809
PMCID:
PMC5748218
DOI:
10.1073/pnas.1716305114
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for HighWire Icon for PubMed Central
Loading ...
Support Center