Chaperone-mediated pathway of proteasome regulatory particle assembly

Roelofs, Jeroen; Park, Soyeon; Haas, Wilhelm; Tian, Geng; McAllister, Fiona E.; Huo, Ying; Lee, Byung‐Hoon; Fan, Zhengqiu; Shi, Yigong; Gygi, Steven P.; Finley, Daniel

doi:10.1038/nature08063

Cited by 172 publications

(343 citation statements)

References 30 publications

(60 reference statements)

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“…Our FCS analysis did not detect proteasome assembly intermediates in wild-type cells, probably because such intermediates are not abundant [37][38][39][40] . Previous studies using a specific importin-a mutant, srp1-49, suggested that nucleocytoplasmic transport mediated by importin a/b is coupled to proteasome biogenesis [19][20][21]23 .…”

Section: Resultsmentioning

confidence: 92%

Quantitative live-cell imaging reveals spatio-temporal dynamics and cytoplasmic assembly of the 26S proteasome

et al. 2014

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The 26S proteasome is a 2.5-MDa multisubunit protease complex that degrades polyubiquitylated proteins. Although its functions and structure have been extensively characterized, little is known about its dynamics in living cells. Here, we investigate the absolute concentration, spatio-temporal dynamics and complex formation of the proteasome in living cells using fluorescence correlation spectroscopy. We find that the 26S proteasome complex is highly mobile, and that almost all proteasome subunits throughout the cell are stably incorporated into 26S proteasomes. The interaction between 19S and 20S particles is stable even in an importin-a mutant, suggesting that the 26S proteasome is assembled in the cytoplasm. Furthermore, a genetically stabilized 26S proteasome mutant is able to enter the nucleus. These results suggest that the 26S proteasome completes its assembly process in the cytoplasm and translocates into the nucleus through the nuclear pore complex as a holoenzyme.

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Section: Resultsmentioning

confidence: 92%

Quantitative live-cell imaging reveals spatio-temporal dynamics and cytoplasmic assembly of the 26S proteasome

et al. 2014

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“…Lesser amounts of the Rpt subunits sedimented at a position characteristic of free intact PA700. Small but detectable amounts of several subunits, including Rpt3, Rpt4, and Rpt5, sedimented significantly slower than intact PA700 and probably represent subassemblies of PA700 described previously (29,30,32).…”

Section: Resultsmentioning

confidence: 99%

C Termini of Proteasomal ATPases Play Nonequivalent Roles in Cellular Assembly of Mammalian 26 S Proteasome

Kim

DeMartino

2011

Journal of Biological Chemistry

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The 26 S proteasome comprises two multisubunit subcomplexes as follows: 20 S proteasome and PA700/19 S regulatory particle. The cellular mechanisms by which these subcomplexes assemble into 26 S proteasome and the molecular determinants that govern the assembly process are poorly defined. Here, we demonstrate the nonequivalent roles of the C termini of six AAA subunits (Rpt1-Rpt6) of PA700 in 26 S proteasome assembly in mammalian cells. The C-terminal HbYX motif (where Hb is a hydrophobic residue, Y is tyrosine, and X is any amino acid) of each of two subunits, Rpt3 and Rpt5, but not that of a third subunit Rpt2, was essential for assembly of 26 S proteasome. The C termini of none of the three non-HbYX motif Rpt subunits were essential for cellular 26 S proteasome assembly, although deletion of the last three residues of Rpt6 destabilized the 20 S-PA700 interaction. Rpt subunits defective for assembly into 26 S proteasome due to C-terminal truncations were incorporated into intact PA700. Moreover, intact PA700 accumulated as an isolated subcomplex when cellular 20 S proteasome content was reduced by RNAi. These results indicate that 20 S proteasome is not an obligatory template for assembly of PA700. Collectively, these results identify specific structural elements of two Rpt subunits required for 26 S proteasome assembly, demonstrate that PA700 can be assembled independently of the 20 S proteasome, and suggest that intact PA700 is a direct intermediate in the cellular pathway of 26 S proteasome assembly.

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“…Two competing models exist for RP assembly ( Funakoshi et al , 2009; Le Tallec et al , 2009; Park et al , 2009; Roelofs et al , 2009). The first posits that RP assembly occurs in modules independent of the CP with the help of four RP-dedicated chaperones, named Hsm3, Nas2, Nas6 and Rpn14 ( Funakoshi et al , 2009).…”

Section: Discussion/analysis Of the Literaturementioning

confidence: 99%

Intracellular Dynamics of the Ubiquitin-Proteasome-System

Chowdhury

Enenkel

2015

F1000Res

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The ubiquitin-proteasome system is the major degradation pathway for short-lived proteins in eukaryotic cells. Targets of the ubiquitin-proteasome-system are proteins regulating a broad range of cellular processes including cell cycle progression, gene expression, the quality control of proteostasis and the response to geno- and proteotoxic stress. Prior to degradation, the proteasomal substrate is marked with a poly-ubiquitin chain. The key protease of the ubiquitin system is the proteasome. In dividing cells, proteasomes exist as holo-enzymes composed of regulatory and core particles. The regulatory complex confers ubiquitin-recognition and ATP dependence on proteasomal protein degradation. The catalytic sites are located in the proteasome core particle. Proteasome holo-enzymes are predominantly nuclear suggesting a major requirement for proteasomal proteolysis in the nucleus. In cell cycle arrested mammalian or quiescent yeast cells, proteasomes deplete from the nucleus and accumulate in granules at the nuclear envelope (NE) / endoplasmic reticulum (ER) membranes. In prolonged quiescence, proteasome granules drop off the NE / ER membranes and migrate as stable organelles throughout the cytoplasm, as thoroughly investigated in yeast. When quiescence yeast cells are allowed to resume growth, proteasome granules clear and proteasomes are rapidly imported into the nucleus.Here, we summarize our knowledge about the enigmatic structure of proteasome storage granules and the trafficking of proteasomes and their substrates between the cyto- and nucleoplasm.Most of our current knowledge is based on studies in yeast. Their translation to mammalian cells promises to provide keen insight into protein degradation in non-dividing cells which comprise the majority of our body’s cells.

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Chaperone-mediated pathway of proteasome regulatory particle assembly

Cited by 172 publications

References 30 publications

Quantitative live-cell imaging reveals spatio-temporal dynamics and cytoplasmic assembly of the 26S proteasome

Quantitative live-cell imaging reveals spatio-temporal dynamics and cytoplasmic assembly of the 26S proteasome

C Termini of Proteasomal ATPases Play Nonequivalent Roles in Cellular Assembly of Mammalian 26 S Proteasome

Intracellular Dynamics of the Ubiquitin-Proteasome-System

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