scholarly journals Hse1, a Component of the Yeast Hrs-STAM Ubiquitin-sorting Complex, Associates with Ubiquitin Peptidases and a Ligase to Control Sorting Efficiency into Multivesicular Bodies

2007 ◽  
Vol 18 (1) ◽  
pp. 324-335 ◽  
Author(s):  
Jihui Ren ◽  
Younghoon Kee ◽  
Jon M. Huibregtse ◽  
Robert C. Piper
Keyword(s):  
Functional Analysis ◽  
Membrane Proteins ◽  
Ubiquitin Ligase ◽  
Integral Membrane Proteins ◽  
Multivesicular Bodies ◽  
C Terminus ◽  
Cargo Proteins ◽  
Sorting Receptor ◽  
Sorting Efficiency ◽  
Novel Protein

Ubiquitinated integral membrane proteins are delivered to the interior of the lysosome/vacuole for degradation. This process relies on specific ubiquitination of potential cargo and recognition of that Ub-cargo by sorting receptors at multiple compartments. We show that the endosomal Hse1-Vps27 sorting receptor binds to ubiquitin peptidases and the ubiquitin ligase Rsp5. Hse1 is linked to Rsp5 directly via a PY element within its C-terminus and through a novel protein Hua1, which recruits a complex of Rsp5, Rup1, and Ubp2. The SH3 domain of Hse1 also binds to the deubiquitinating protein Ubp7. Functional analysis shows that when both modes of Rsp5 association with Hse1 are altered, sorting of cargo that requires efficient ubiquitination for entry into the MVB is blocked, whereas sorting of cargo containing an in-frame addition of ubiquitin is normal. Further deletion of Ubp7 restores sorting of cargo when the Rsp5:Hse1 interaction is compromised suggesting that both ubiquitin ligases and peptidases associate with the Hse1-Vps27 sorting complex to control the ubiquitination status and sorting efficiency of cargo proteins. Additionally, we find that disruption of UBP2 and RUP1 inhibits MVB sorting of some cargos suggesting that Rsp5 requires association with Ubp2 to properly ubiquitinate cargo for efficient MVB sorting.

scholarly journals The Yeast vps Class E Mutants: The Beginning of the Molecular Genetic Analysis of Multivesicular Body Biogenesis

2010 ◽  
Vol 21 (23) ◽  
pp. 4057-4060 ◽  
Author(s):  
Emily M. Coonrod ◽  
Tom H. Stevens
Keyword(s):  
Membrane Proteins ◽  
Molecular Genetic ◽  
Multivesicular Body ◽  
Molecular Genetic Analysis ◽  
Vacuolar Membrane ◽  
Multivesicular Bodies ◽  
Golgi Membrane ◽  
Cargo Proteins ◽  
Vacuolar Protein ◽  
Class E

In 1992, Raymond et al. published a compilation of the 41 yeast vacuolar protein sorting (vps) mutant groups and described a large class of mutants (class E vps mutants) that accumulated an exaggerated prevacuolar endosome-like compartment. Further analysis revealed that this “class E compartment” contained soluble vacuolar hydrolases, vacuolar membrane proteins, and Golgi membrane proteins unable to recycle back to the Golgi complex, yet these class E vps mutants had what seemed to be normal vacuoles. The 13 class E VPS genes were later shown to encode the proteins that make up the complexes required for formation of intralumenal vesicles in late endosomal compartments called multivesicular bodies, and for the sorting of ubiquitinated cargo proteins into these internal vesicles for eventual delivery to the vacuole or lysosome.

scholarly journals Atypical parkinsonism–associated retromer mutant alters endosomal sorting of specific cargo proteins

2016 ◽  
Vol 214 (4) ◽  
pp. 389-399 ◽  
Author(s):  
Kirsty J. McMillan ◽  
Matthew Gallon ◽  
Adam P. Jellett ◽  
Thomas Clairfeuille ◽  
Frances C. Tilley ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Neurodegenerative Disease ◽  
Quantitative Proteomics ◽  
Protein Complexes ◽  
Integral Membrane Proteins ◽  
Atypical Parkinsonism ◽  
Endosomal Sorting ◽  
Retromer Complex ◽  
Cargo Proteins ◽  
Cargo Sorting

The retromer complex acts as a scaffold for endosomal protein complexes that sort integral membrane proteins to various cellular destinations. The retromer complex is a heterotrimer of VPS29, VPS35, and VPS26. Two of these paralogues, VPS26A and VPS26B, are expressed in humans. Retromer dysfunction is associated with neurodegenerative disease, and recently, three VPS26A mutations (p.K93E, p.M112V, and p.K297X) were discovered to be associated with atypical parkinsonism. Here, we apply quantitative proteomics to provide a detailed description of the retromer interactome. By establishing a comparative proteomic methodology, we identify how this interactome is perturbed in atypical parkinsonism-associated VPS26A mutants. In particular, we describe a selective defect in the association of VPS26A (p.K297X) with the SNX27 cargo adaptor. By showing how a retromer mutant leads to altered endosomal sorting of specific PDZ ligand–containing cargo proteins, we reveal a new mechanism for perturbed endosomal cargo sorting in atypical parkinsonism.

scholarly journals Direct Binding to Rsp5p Regulates Ubiquitination-independent Vacuolar Transport of Sna3p

2007 ◽  
Vol 18 (5) ◽  
pp. 1781-1789 ◽  
Author(s):  
Hadiya Watson ◽  
Juan S. Bonifacino
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Ubiquitin Ligase ◽  
Adaptor Protein ◽  
Direct Interaction ◽  
Integral Membrane Proteins ◽  
Multivesicular Bodies ◽  
Hect Domain ◽  
Ww Domains ◽  
Cytosolic Domains ◽  
Direct Binding

The sorting of integral membrane proteins such as carboxypeptidase S (Cps1p) into the luminal vesicles of multivesicular bodies (MVBs) in Saccharomyces cerevisiae requires ubiquitination of their cytosolic domains by the ubiquitin ligases Rsp5p and/or Tul1p. An exception is Sna3p, which does not require ubiquitination for entry into MVBs. The mechanism underlying this ubiquitination-independent MVB sorting pathway has not yet been characterized. Here, we show that Sna3p sorting into the MVB pathway depends on a direct interaction between a PPAY motif within its C-terminal cytosolic tail and the WW domains of Rsp5p. Disruption of this interaction inhibits vacuolar targeting of Sna3p and causes its accumulation in a compartment that overlaps only partially with MVBs. Surprisingly, Sna3p does require a functional ubiquitin-ligase HECT domain within Rsp5p; however, the dependence of Sna3p on HECT domain activity is distinct from that of Cps1p. Last, we show that Sna3p requires neither Tul1p nor the transmembrane adaptor protein Bsd2p for its MVB sorting. Our data demonstrate that Sna3p follows a novel ubiquitination-independent, but Rsp5p-mediated, sorting pathway to the vacuole.

Biogenesis of tail-anchored proteins

2003 ◽  
Vol 31 (6) ◽  
pp. 1238-1242 ◽  
Author(s):  
N. Borgese ◽  
S. Brambillasca ◽  
P. Soffientini ◽  
M. Yabal ◽  
M. Makarow
Keyword(s):  
Amino Acids ◽  
Endoplasmic Reticulum ◽  
Membrane Proteins ◽  
Recent Work ◽  
Integral Membrane Proteins ◽  
Phospholipid Bilayer ◽  
Endoplasmic Reticulum Membrane ◽  
Regulatory Processes ◽  
C Terminus ◽  
Hydrophobic Amino Acids

A group of integral membrane proteins, known as C-tail anchored, is defined by the presence of a cytosolic N-terminal domain that is anchored to the phospholipid bilayer by a single segment of hydrophobic amino acids close to the C-terminus. The mode of insertion into membranes of these proteins, many of which play key roles in fundamental intracellular processes, is obligatorily post-translational, is highly specific and may be subject to regulatory processes that modulate the protein's function. Recent work has demonstrated that tail-anchored proteins translocate their C-termini across the endoplasmic reticulum membrane by a mechanism different from that used for Sec61-dependent post-translational signal-peptide-driven translocation. Here we summarize recent results on the insertion of tail-anchored proteins and discuss possible mechanisms that could be involved.

A transmembrane ubiquitin ligase required to sort membrane proteins into multivesicular bodies

2002 ◽  
Vol 4 (2) ◽  
pp. 117-123 ◽  
Author(s):  
Fulvio Reggiori ◽  
Hugh R. B. Pelham
Keyword(s):  
Membrane Proteins ◽  
Ubiquitin Ligase ◽  
Multivesicular Bodies

scholarly journals Ear1p and Ssh4p Are New Adaptors of the Ubiquitin Ligase Rsp5p for Cargo Ubiquitylation and Sorting at Multivesicular Bodies

2008 ◽  
Vol 19 (6) ◽  
pp. 2379-2388 ◽  
Author(s):  
Sébastien Léon ◽  
Zoi Erpapazoglou ◽  
Rosine Haguenauer-Tsapis
Keyword(s):  
Plasma Membrane ◽  
Membrane Proteins ◽  
Ubiquitin Ligase ◽  
Multivesicular Bodies ◽  
Endosomal Sorting ◽  
Frame Fusion ◽  
Vacuolar Targeting

The ubiquitylation of membrane proteins destined for the vacuole/lysosome is essential for their recognition by the endosomal sorting machinery and their internalization into vesicles of multivesicular bodies (MVBs). In yeast, this process requires Rsp5p, an essential ubiquitin ligase of the Nedd4 family. We describe here two redundant proteins, Ear1p and Ssh4p, required for the vacuolar targeting of several cargoes originating from the Golgi or the plasma membrane. Ear1p is an endosomal protein that interacts with Rsp5p through its PPxY motifs, and it is required for the ubiquitylation of selected cargoes before their MVB sorting. In-frame fusion of cargo to ubiquitin overcomes the need for Ear1p/Ssh4p, confirming a role for these proteins in cargo ubiquitylation. Interestingly, Ear1p is itself ubiquitylated by Rsp5p and targeted to the vacuole. Finally, Ear1p overexpression leads to Rsp5p accumulation at endosomes, interfering with some of its functions in trafficking. Therefore, Ear1p/Ssh4p recruit Rsp5p and assist it in its function at MVBs by directing the ubiquitylation of specific cargoes.

The Ubiquitin Ligase Rsp5p is Required for Modification and Sorting of Membrane Proteins into Multivesicular Bodies

Traffic ◽  
2004 ◽  
Vol 5 (5) ◽  
pp. 383-392 ◽  
Author(s):  
Joelle Morvan ◽  
Marine Froissard ◽  
Rosine Haguenauer-Tsapis ◽  
Danièle Urban-Grimal
Keyword(s):  
Membrane Proteins ◽  
Ubiquitin Ligase ◽  
Multivesicular Bodies

scholarly journals The ART-Rsp5 ubiquitin ligase network comprises a plasma membrane quality control system that protects yeast cells from proteotoxic stress

eLife ◽  
2013 ◽  
Vol 2 ◽  
Author(s):  
Yingying Zhao ◽  
Jason A MacGurn ◽  
Max Liu ◽  
Scott Emr
Keyword(s):  
Quality Control ◽  
Plasma Membrane ◽  
Control System ◽  
Membrane Proteins ◽  
Cell Surface ◽  
Ubiquitin Ligase ◽  
Integral Membrane Proteins ◽  
Quality Control System ◽  
Er Quality Control ◽  
Proteotoxic Stress

Secretory cargo that cannot fold properly in the ER are selectively targeted for removal by a well-studied ER-associated degradation pathway, or ERAD. In contrast, very little is known about post-ER quality control mechanisms for damaged or misfolded integral membrane proteins. Here we describe a quality control function of the Rsp5-ART ubiquitin ligase adaptor network that functions to protect plasma membrane (PM) integrity. Failure to mediate this protective response during heat stress leads to toxic accumulation of misfolded integral membrane proteins at the cell surface, which causes loss of PM integrity and cell death. Thus, the Rsp5-ART network comprises a PM quality control system that works together with sequential quality control pathways in the ER and Golgi to (i) target the degradation of proteins that have exceeded their functional lifetime due to damage and/or misfolding and (ii) limit the toxic accumulation of specific proteins at the cell surface during proteotoxic stress.

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