Regulation of ER-associated degradation via p97/VCP-interacting motif

2008 ◽  
Vol 36 (5) ◽  
pp. 818-822 ◽  
Author(s):  
Petek Ballar ◽  
Shengyun Fang
Keyword(s):  
Endoplasmic Reticulum ◽  
Ubiquitin Ligase ◽  
Terminal Region ◽  
Misfolded Proteins ◽  
Interacting Protein ◽  
Aaa Atpase ◽  
Endoplasmic Reticulum Associated Degradation ◽  
Er Membrane

p97/VCP (valosin-containing protein) is a cytosolic AAA (ATPase associated with various cellular activities) essential for retrotranslocation of misfolded proteins during ERAD [ER (endoplasmic reticulum)-associated degradation]. gp78, an ERAD ubiquitin ligase, is one of the p97/VCP recruitment proteins localized to the ER membrane. A newly identified VIM (p97/VCP-interacting motif) in gp78 has brought about novel insights into mechanisms of ERAD, such as the presence of a p97/VCP-dependent but Ufd1-independent retrotranslocation during gp78-mediated ERAD. Additionally, SVIP (small p97/VCP-interacting protein), which contains a VIM in its N-terminal region, negatively regulates ERAD by uncoupling p97/VCP and Derlin1 from gp78. Thus SVIP may protect cells from damage by extravagant ERAD.

scholarly journals Ubx4 Modulates Cdc48 Activity and Influences Degradation of Misfolded Proteins of the Endoplasmic Reticulum

2009 ◽  
Vol 284 (24) ◽  
pp. 16082-16089 ◽  
Author(s):  
Sven M. Alberts ◽  
Caroline Sonntag ◽  
Antje Schäfer ◽  
Dieter H. Wolf
Keyword(s):  
Endoplasmic Reticulum ◽  
Secretory Pathway ◽  
Ubiquitin Proteasome System ◽  
Misfolded Proteins ◽  
Aaa Atpase ◽  
Cytosolic Side ◽  
Ubiquitin Proteasome ◽  
Correct Function ◽  
Er Membrane

Misfolded proteins of the secretory pathway are recognized in the endoplasmic reticulum (ER), retrotranslocated into the cytoplasm, and degraded by the ubiquitin-proteasome system. Right after retrotranslocation and polyubiquitination, they are extracted from the cytosolic side of the ER membrane through a complex consisting of the AAA ATPase Cdc48 (p97 in mammals), Ufd1, and Npl4. This complex delivers misfolded proteins to the proteasome for final degradation. Extraction, delivery, and processing of ERAD (ER-associated degradation) substrates to the proteasome requires additional cofactors of Cdc48. Here we characterize the UBX domain containing protein Ubx4 (Cui1) as a crucial factor for the degradation of polyubiquitinated proteins via ERAD. Ubx4 modulates the Cdc48-Ufd1-Npl4 complex to guarantee its correct function. Mutant variants of Ubx4 lead to defective degradation of misfolded proteins and accumulation of polyubiquitinated proteins bound to Cdc48. We show the requirement of the UBX domain of Ubx4 for its function in ERAD. The observation that Ubx2 and Ubx4 are not found together in one complex with Cdc48 suggests several distinct steps in modulating the activity and localization of Cdc48 in ERAD.

scholarly journals AAA ATPase p97/Valosin-containing Protein Interacts with gp78, a Ubiquitin Ligase for Endoplasmic Reticulum-associated Degradation

2004 ◽  
Vol 279 (44) ◽  
pp. 45676-45684 ◽  
Author(s):  
Xiaoyan Zhong ◽  
Yuxian Shen ◽  
Petek Ballar ◽  
Andria Apostolou ◽  
Reuven Agami ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Ubiquitin Ligase ◽  
Protein Quality ◽  
Proteasomal Degradation ◽  
Degradation Pathway ◽  
Aaa Atpase ◽  
Endoplasmic Reticulum Associated Degradation ◽  
Ubiquitin Ligase E3 ◽  
Quality Control Mechanism ◽  
Interacting Domain

Endoplasmic reticulum-associated degradation (ERAD) is a protein quality control mechanism that eliminates unwanted proteins from the endoplasmic reticulum (ER) through a ubiquitin-dependent proteasomal degradation pathway. gp78 is a previously described ER membrane-anchored ubiquitin ligase (E3) involved in ubiquitination of ER proteins. AAA ATPase (ATPase associated with various cellular activities) p97/valosin-containing protein (VCP) subsequently dislodges the ubiquitinated proteins from the ER and chaperones them to the cytosol, where they undergo proteasomal degradation. We now report that gp78 physically interacts with p97/VCP and enhances p97/VCP-polyubiquitin association. The enhanced association correlates with decreases in ER stress-induced accumulation of polyubiquitinated proteins. This effect is abolished when the p97/VCP-interacting domain of gp78 is removed. Further, using ERAD substrate CD3δ, gp78 consistently enhances p97/VCP-CD3δ binding and facilitates CD3δ degradation. Moreover, inhibition of endogenous gp78 expression by RNA interference markedly increases the levels of total polyubiquitinated proteins, including CD3δ, and abrogates VCP-CD3δ interactions. The gp78 mutant with deletion of its p97/VCP-interacting domain fails to increase CD3δ degradation and leads to accumulation of polyubiquitinated CD3δ, suggesting a failure in delivering ubiquitinated CD3δ for degradation. These data suggest that gp78-p97/VCP interaction may represent one way of coupling ubiquitination with retrotranslocation and degradation of ERAD substrates.

scholarly journals Cycles of autoubiquitination and deubiquitination regulate the ERAD ubiquitin ligase Hrd1

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Brian G Peterson ◽  
Morgan L Glaser ◽  
Tom A Rapoport ◽  
Ryan D Baldridge
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Proteins ◽  
Ubiquitin Ligase ◽  
Ground State ◽  
Inhibitory Effect ◽  
The Other ◽  
Misfolded Proteins ◽  
Deubiquitinating Enzyme ◽  
Transmembrane Segment

Misfolded proteins in the lumen of the endoplasmic reticulum (ER) are retrotranslocated into the cytosol and polyubiquitinated before being degraded by the proteasome. The multi-spanning ubiquitin ligase Hrd1 forms the retrotranslocation channel and associates with three other membrane proteins (Hrd3, Usa1, Der1) of poorly defined function. The Hrd1 channel is gated by autoubiquitination, but how Hrd1 escapes degradation by the proteasome and returns to its inactive ground state is unknown. Here, we show that autoubiquitination of Hrd1 is counteracted by Ubp1, a deubiquitinating enzyme that requires its N-terminal transmembrane segment for activity towards Hrd1. The Hrd1 partner Hrd3 serves as a brake for autoubiquitination, while Usa1 attenuates Ubp1’s deubiquitination activity through an inhibitory effect of its UBL domain. These results lead to a model in which the Hrd1 channel is regulated by cycles of autoubiquitination and deubiquitination, reactions that are modulated by the other components of the Hrd1 complex.

scholarly journals A stalled retrotranslocation complex reveals physical linkage between substrate recognition and proteasomal degradation during ER-associated degradation

2013 ◽  
Vol 24 (11) ◽  
pp. 1765-1775 ◽  
Author(s):  
Kunio Nakatsukasa ◽  
Jeffrey L. Brodsky ◽  
Takumi Kamura
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Proteins ◽  
Ubiquitin Ligase ◽  
Substrate Recognition ◽  
Proteasomal Degradation ◽  
26S Proteasome ◽  
Endoplasmic Reticulum Associated Degradation ◽  
Ubiquitin Ligase Complex ◽  
Physical Linkage ◽  
Tightly Coupled

During endoplasmic reticulum–associated degradation (ERAD), misfolded lumenal and membrane proteins in the ER are recognized by the transmembrane Hrd1 ubiquitin ligase complex and retrotranslocated to the cytosol for ubiquitination and degradation. Although substrates are believed to be delivered to the proteasome only after the ATPase Cdc48p/p97 acts, there is limited knowledge about how the Hrd1 complex coordinates with Cdc48p/p97 and the proteasome to orchestrate substrate recognition and degradation. Here we provide evidence that inactivation of Cdc48p/p97 stalls retrotranslocation and triggers formation of a complex that contains the 26S proteasome, Cdc48p/p97, ubiquitinated substrates, select components of the Hrd1 complex, and the lumenal recognition factor, Yos9p. We propose that the actions of Cdc48p/p97 and the proteasome are tightly coupled during ERAD. Our data also support a model in which the Hrd1 complex links substrate recognition and degradation on opposite sides of the ER membrane.

scholarly journals p97 Is in a Complex with Cholera Toxin and Influences the Transport of Cholera Toxin and Related Toxins to the Cytoplasm

2005 ◽  
Vol 280 (16) ◽  
pp. 15865-15871 ◽  
Author(s):  
Ramzey J. AbuJarour ◽  
Seema Dalal ◽  
Phyllis I. Hanson ◽  
Rockford K. Draper
Keyword(s):  
Endoplasmic Reticulum ◽  
Cholera Toxin ◽  
Vero Cells ◽  
Degradation Pathway ◽  
Endoplasmic Reticulum Membrane ◽  
Toxin A ◽  
Aaa Atpase ◽  
Endoplasmic Reticulum Associated Degradation ◽  
Protein Toxins ◽  
A Chain

Certain protein toxins, including cholera toxin, ricin, andPseudomonas aeruginosaexotoxin A, are transported to the lumen of the endoplasmic reticulum where they retro-translocate across the endoplasmic reticulum membrane to enter the cytoplasm. The mechanism of retrotranslocation is poorly understood but may involve the endoplasmic reticulum-associated degradation pathway. The AAA ATPase p97 (also called valosin-containing protein) participates in the retro-translocation of cellular endoplasmic reticulum-associated degradation substrates and is therefore a candidate to participate in the retrotranslocation of protein toxins. To investigate whether p97 functions in toxin delivery to the cytoplasm, we measured the sensitivity to toxins of cells expressing either wild-type p97 or a dominant ATPase-defective p97 mutant under control of a tetracycline-inducible promoter. The rate at which cholera toxin and related toxins entered the cytoplasm was reduced in cells expressing the ATPase-defective p97, suggesting that the toxins might interact with p97. To detect interaction, the cholera toxin A chain was immunoprecipitated from cholera toxin-treated Vero cells, and co-immunoprecipitation of p97 was assessed by immunoblotting. The immunoprecipitates contained both cholera toxin A chain and p97, evidence that the two proteins are in a complex. Altogether, these results provide functional and structural evidence that p97 participates in the transport of cholera toxin to the cytoplasm.

scholarly journals The Heat Shock Protein 40-Type Chaperone MASH Supports the Endoplasmic Reticulum-Associated Degradation E3 Ubiquitin Ligase MAKIBISHI1 in Medicago truncatula

2021 ◽  
Vol 12 ◽  
Author(s):  
Marie-Laure Erffelinck ◽  
Bianca Ribeiro ◽  
Lore Gryffroy ◽  
Avanish Rai ◽  
Jacob Pollier ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Heat Shock ◽  
Heat Shock Protein ◽  
Medicago Truncatula ◽  
Ubiquitin Ligase ◽  
Protein Quality ◽  
E3 Ubiquitin Ligase ◽  
Metabolic Phenotype ◽  
Endoplasmic Reticulum Associated Degradation ◽  
Control Apparatus

Jasmonates (JA) are oxylipin-derived phytohormones that trigger the production of specialized metabolites that often serve in defense against biotic stresses. In Medicago truncatula, a JA-induced endoplasmic reticulum-associated degradation (ERAD)-type machinery manages the production of bioactive triterpenes and thereby secures correct plant metabolism, growth, and development. This machinery involves the conserved RING membrane-anchor (RMA)-type E3 ubiquitin ligase MAKIBISHI1 (MKB1). Here, we discovered two additional members of this protein control apparatus via a yeast-based protein–protein interaction screen and characterized their function. First, a cognate E2 ubiquitin-conjugating enzyme was identified that interacts with MKB1 to deliver activated ubiquitin and to mediate its ubiquitination activity. Second, we identified a heat shock protein 40 (HSP40) that interacts with MKB1 to support its activity and was therefore designated MKB1-supporting HSP40 (MASH). MASH expression was found to be co-regulated with that of MKB1. The presence of MASH is critical for MKB1 and ERAD functioning because the dramatic morphological, transcriptional, and metabolic phenotype of MKB1 knock-down M. truncatula hairy roots was phenocopied by silencing of MASH. Interaction was also observed between the Arabidopsis thaliana (Arabidopsis) homologs of MASH and MKB1, suggesting that MASH represents an essential and plant-specific component of this vital and conserved eukaryotic protein quality control machinery.

scholarly journals Unassembled CD147 is an endogenous endoplasmic reticulum–associated degradation substrate

2012 ◽  
Vol 23 (24) ◽  
pp. 4668-4678 ◽  
Author(s):  
Ryan E. Tyler ◽  
Margaret M. P. Pearce ◽  
Thomas A. Shaler ◽  
James A. Olzmann ◽  
Ethan J. Greenblatt ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Ubiquitin Ligase ◽  
Adaptor Protein ◽  
Monocarboxylate Transporters ◽  
Dependent Manner ◽  
Conserved Residues ◽  
Mutant Proteins ◽  
Endoplasmic Reticulum Associated Degradation ◽  
Assembly Factor ◽  
Endogenous Substrate

Degradation of folding- or assembly-defective proteins by the endoplasmic reticulum–associated degradation (ERAD) ubiquitin ligase, Hrd1, is facilitated by a process that involves recognition of demannosylated N-glycans by the lectin OS-9/XTP3-B via the adaptor protein SEL1L. Most of our knowledge of the machinery that commits proteins to this fate in metazoans comes from studies of overexpressed mutant proteins in heterologous cells. In this study, we used mass spectrometry to identify core-glycoslyated CD147 (CD147(CG)) as an endogenous substrate of the ERAD system that accumulates in a complex with OS-9 following SEL1L depletion. CD147 is an obligatory assembly factor for monocarboxylate transporters. The majority of newly synthesized endogenous CD147(CG) was degraded by the proteasome in a Hrd1-dependent manner. CD147(CG) turnover was blocked by kifunensine, and interaction of OS-9 and XTP3-B with CD147(CG) was inhibited by mutations to conserved residues in their lectin domains. These data establish unassembled CD147(CG) as an endogenous, constitutive ERAD substrate of the OS-9/SEL1L/Hrd1 pathway.

scholarly journals Characterization of protein complexes of the endoplasmic reticulum-associated degradation E3 ubiquitin ligase Hrd1

2017 ◽  
Vol 292 (22) ◽  
pp. 9104-9116 ◽  
Author(s):  
Jiwon Hwang ◽  
Christopher P. Walczak ◽  
Thomas A. Shaler ◽  
James A. Olzmann ◽  
Lichao Zhang ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Ubiquitin Ligase ◽  
Protein Complexes ◽  
E3 Ubiquitin Ligase ◽  
Endoplasmic Reticulum Associated Degradation
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