ESCRT-mediated sorting and intralumenal vesicle concatenation in plants

2018 ◽  
Vol 46 (3) ◽  
pp. 537-545 ◽  
Author(s):  
Marisa S. Otegui
Keyword(s):  
Plasma Membrane ◽  
Membrane Proteins ◽  
Endocytic Pathway ◽  
Endosomal Sorting ◽  
Evolutionary Diversification ◽  
Escrt Machinery ◽  
Membrane Fission ◽  
Associated Proteins

The degradation of plasma membrane and other membrane-associated proteins require their sorting at endosomes for delivery to the vacuole. Through the endocytic pathway, ubiquitinated membrane proteins (cargo) are delivered to endosomes where the ESCRT (endosomal sorting complex required for transport) machinery sorts them into intralumenal vesicles for degradation. Plants contain both conserved and plant-specific ESCRT subunits. In this review, I discuss the role of characterized plant ESCRT components, the evolutionary diversification of the plant ESCRT machinery, and a recent study showing that endosomal intralumenal vesicles form in clusters of concatenated vesicle buds by temporally uncoupling membrane constriction from membrane fission.

scholarly journals ESCRT-dependent targeting of plasma membrane localized KCa3.1 to the lysosomes

2010 ◽  
Vol 299 (5) ◽  
pp. C1015-C1027 ◽  
Author(s):  
Corina M. Balut ◽  
Yajuan Gao ◽  
Sandra A. Murray ◽  
Patrick H. Thibodeau ◽  
Daniel C. Devor
Keyword(s):  
Plasma Membrane ◽  
Molecular Mechanisms ◽  
Close Association ◽  
Significant Inhibition ◽  
Dominant Negative ◽  
Human Embryonic Kidney Cells ◽  
Endosomal Sorting ◽  
Escrt Machinery ◽  
Interfering Rna

The number of intermediate-conductance, Ca2+-activated K+ channels (KCa3.1) present at the plasma membrane is deterministic in any physiological response. However, the mechanisms by which KCa3.1 channels are removed from the plasma membrane and targeted for degradation are poorly understood. Recently, we demonstrated that KCa3.1 is rapidly internalized from the plasma membrane, having a short half-life in both human embryonic kidney cells (HEK293) and human microvascular endothelial cells (HMEC-1). In this study, we investigate the molecular mechanisms controlling the degradation of KCa3.1 heterologously expressed in HEK and HMEC-1 cells. Using immunofluorescence and electron microscopy, as well as quantitative biochemical analysis, we demonstrate that membrane KCa3.1 is targeted to the lysosomes for degradation. Furthermore, we demonstrate that either overexpressing a dominant negative Rab7 or short interfering RNA-mediated knockdown of Rab7 results in a significant inhibition of channel degradation rate. Coimmunoprecipitation confirmed a close association between Rab7 and KCa3.1. On the basis of these findings, we assessed the role of the ESCRT machinery in the degradation of heterologously expressed KCa3.1, including TSG101 [endosomal sorting complex required for transport (ESCRT)-I] and CHMP4 (ESCRT-III) as well as VPS4, a protein involved in the disassembly of the ESCRT machinery. We demonstrate that TSG101 is closely associated with KCa3.1 via coimmunoprecipitation and that a dominant negative TSG101 inhibits KCa3.1 degradation. In addition, both dominant negative CHMP4 and VPS4 significantly decrease the rate of membrane KCa3.1 degradation, compared with wild-type controls. These results are the first to demonstrate that plasma membrane-associated KCa3.1 is targeted for lysosomal degradation via a Rab7 and ESCRT-dependent pathway.

scholarly journals Proteasome Inhibitors Block a Late Step in Lysosomal Transport of Selected Membrane but not Soluble Proteins

2001 ◽  
Vol 12 (8) ◽  
pp. 2556-2566 ◽  
Author(s):  
Peter van Kerkhof ◽  
Cristina M. Alves dos Santos ◽  
Martin Sachse ◽  
Judith Klumperman ◽  
Guojun Bu ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Proteasome Inhibitors ◽  
Endocytic Pathway ◽  
Endosomal Sorting ◽  
Ubiquitin Proteasome Pathway ◽  
Late Step ◽  
Ubiquitin Proteasome ◽  
Proteasome Pathway ◽  
Lysosomal Transport

The ubiquitin-proteasome pathway acts as a regulator of the endocytosis of selected membrane proteins. Recent evidence suggests that it may also function in the intracellular trafficking of membrane proteins. In this study, several models were used to address the role of the ubiquitin-proteasome pathway in sorting of internalized proteins to the lysosome. We found that lysosomal degradation of ligands, which remain bound to their receptors within the endocytic pathway, is blocked in the presence of specific proteasome inhibitors. In contrast, a ligand that dissociates from its receptor upon endosome acidification is degraded under the same conditions. Quantitative electron microscopy showed that neither the uptake nor the overall distribution of the endocytic marker bovine serum albumin-gold is substantially altered in the presence of a proteasome inhibitor. The data suggest that the ubiquitin-proteasome pathway is involved in an endosomal sorting step of selected membrane proteins to lysosomes, thereby providing a mechanism for regulated degradation.

scholarly journals Arabidopsis SH3P2 is an ubiquitin-binding protein that functions together with ESCRT-I and the deubiquitylating enzyme AMSH3

2017 ◽  
Vol 114 (34) ◽  
pp. E7197-E7204 ◽  
Author(s):  
Marie-Kristin Nagel ◽  
Kamila Kalinowska ◽  
Karin Vogel ◽  
Gregory D. Reynolds ◽  
Zhixiang Wu ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Membrane Proteins ◽  
Stress Responses ◽  
Binding Protein ◽  
In Planta ◽  
Biotic And Abiotic Stress ◽  
Plasma Membrane Proteins ◽  
Endosomal Sorting ◽  
Escrt Machinery ◽  
Ubiquitin Binding

Clathrin-mediated endocytosis of plasma membrane proteins is an essential regulatory process that controls plasma membrane protein abundance and is therefore important for many signaling pathways, such as hormone signaling and biotic and abiotic stress responses. On endosomal sorting, plasma membrane proteins maybe recycled or targeted for vacuolar degradation, which is dependent on ubiquitin modification of the cargos and is driven by the endosomal sorting complexes required for transport (ESCRTs). Components of the ESCRT machinery are highly conserved among eukaryotes, but homologs of ESCRT-0 that are responsible for recognition and concentration of ubiquitylated proteins are absent in plants. Recently several ubiquitin-binding proteins have been identified that serve in place of ESCRT-0; however, their function in ubiquitin recognition and endosomal trafficking is not well understood yet. In this study, we identified Src homology-3 (SH3) domain-containing protein 2 (SH3P2) as a ubiquitin- and ESCRT-I–binding protein that functions in intracellular trafficking. SH3P2 colocalized with clathrin light chain-labeled punctate structures and interacted with clathrin heavy chain in planta, indicating a role for SH3P2 in clathrin-mediated endocytosis. Furthermore, SH3P2 cofractionates with clathrin-coated vesicles (CCVs), suggesting that it associates with CCVs in planta. Mutants of SH3P2 and VPS23 genetically interact, suggesting that they could function in the same pathway. Based on these results, we suggest a role of SH3P2 as an ubiquitin-binding protein that binds and transfers ubiquitylated proteins to the ESCRT machinery.

scholarly journals Essential Role of hIST1 in Cytokinesis

2009 ◽  
Vol 20 (5) ◽  
pp. 1374-1387 ◽  
Author(s):  
Monica Agromayor ◽  
Jez G. Carlton ◽  
John P. Phelan ◽  
Daniel R. Matthews ◽  
Leo M. Carlin ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Multivesicular Body ◽  
Endosomal Sorting ◽  
Escrt Machinery ◽  
Membrane Fission ◽  
Immunodeficiency Virus ◽  
Positive Modulator ◽  
Essential Function ◽  
Hiv 1

The last steps of multivesicular body (MVB) formation, human immunodeficiency virus (HIV)-1 budding and cytokinesis require a functional endosomal sorting complex required for transport (ESCRT) machinery to facilitate topologically equivalent membrane fission events. Increased sodium tolerance (IST) 1, a new positive modulator of the ESCRT pathway, has been described recently, but an essential function of this highly conserved protein has not been identified. Here, we describe the previously uncharacterized KIAA0174 as the human homologue of IST1 (hIST1), and we report its conserved interaction with VPS4, CHMP1A/B, and LIP5. We also identify a microtubule interacting and transport (MIT) domain interacting motif (MIM) in hIST1 that is necessary for its interaction with VPS4, LIP5 and other MIT domain-containing proteins, namely, MITD1, AMSH, UBPY, and Spastin. Importantly, hIST1 is essential for cytokinesis in mammalian cells but not for HIV-1 budding, thus providing a novel mechanism of functional diversification of the ESCRT machinery. Last, we show that the hIST1 MIM activity is essential for cytokinesis, suggesting possible mechanisms to explain the role of hIST1 in the last step of mammalian cell division.

scholarly journals HIV Assembly and Budding: Ca2+ Signaling and Non-ESCRT Proteins Set the Stage

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Lorna S. Ehrlich ◽  
Carol A. Carter
Keyword(s):  
Protein Trafficking ◽  
Endocytic Pathway ◽  
Host Proteins ◽  
Virus Budding ◽  
Endosomal Sorting ◽  
The Past ◽  
Escrt Machinery ◽  
Cellular Factors ◽  
Hiv 1

More than a decade has elapsed since the link between the endosomal sorting complex required for transport (ESCRT) machinery and HIV-1 protein trafficking and budding was first identified. L domains in HIV-1 Gag mediate recruitment of ESCRT which function in bud abscission releasing the viral particle from the host cell. Beyond virus budding, the ESCRT machinery is also involved in the endocytic pathway, cytokinesis, and autophagy. In the past few years, the number of non-ESCRT host proteins shown to be required in the assembly process has also grown. In this paper, we highlight the role of recently identified cellular factors that link ESCRT machinery to calcium signaling machinery and we suggest that this liaison contributes to setting the stage for productive ESCRT recruitment and mediation of abscission. Parallel paradigms for non-ESCRT roles in virus budding and cytokinesis will be discussed.

scholarly journals Membrane manipulations by the ESCRT machinery

F1000Research ◽  
2015 ◽  
Vol 4 ◽  
pp. 516 ◽  
Author(s):  
Greg Odorizzi
Keyword(s):  
Plasma Membrane ◽  
Transmembrane Proteins ◽  
Membrane Dynamics ◽  
Endocytic Pathway ◽  
Current Understanding ◽  
Eukaryotic Cells ◽  
Major Research ◽  
Endosomal Sorting ◽  
Escrt Machinery ◽  
Research Findings

The endosomal sorting complexes required for transport (ESCRTs) collectively comprise a machinery that was first known for its function in the degradation of transmembrane proteins in the endocytic pathway of eukaryotic cells. Since their discovery, however, ESCRTs have been recognized as playing important roles at the plasma membrane, which appears to be the original site of function for the ESCRT machinery. This article reviews some of the major research findings that have shaped our current understanding of how the ESCRT machinery controls membrane dynamics and considers new roles for the ESCRT machinery that might be driven by these mechanisms.

scholarly journals Deubiquitination Step in the Endocytic Pathway of Yeast Plasma Membrane Proteins: Crucial Role of Doa4p Ubiquitin Isopeptidase

2001 ◽  
Vol 21 (14) ◽  
pp. 4482-4494 ◽  
Author(s):  
S. Dupré ◽  
R. Haguenauer-Tsapis
Keyword(s):  
Plasma Membrane ◽  
Membrane Proteins ◽  
Degradation Products ◽  
Endocytic Pathway ◽  
Plasma Membrane Proteins ◽  
General Role ◽  
Yeast Plasma Membrane ◽  
Membrane Bound ◽  
Vacuolar Protein

ABSTRACT The Fur4p uracil permease, like most yeast plasma membrane proteins, undergoes ubiquitin-dependent endocytosis and is then targeted to the vacuole (equivalent to the mammalian lysosome) for degradation. The cell surface ubiquitination of Fur4p is mediated by the essential Rsp5p ubiquitin ligase. Ubiquitination of Fur4p occurs on two target lysines, which receive two ubiquitin moieties linked through ubiquitin Lys63, a type of linkage (termed UbK63) different from that involved in proteasome recognition. We report that pep4cells deficient for vacuolar protease activities accumulate vacuolar unubiquitinated Fur4p. In contrast, pep4 cells lacking the Doa4p ubiquitin isopeptidase accumulate ubiquitin-conjugated Fur4p. These data suggest that Fur4p undergoes Doa4p-dependent deubiquitination prior to vacuolar degradation. Compared topep4 cells, pep4 doa4 cells have huge amounts of membrane-bound ubiquitin conjugates. This indicates that Doa4p plays a general role in the deubiquitination of membrane-bound proteins, as suggested by reports describing the suppression of somedoa4 phenotypes in endocytosis and vacuolar protein sorting mutants. Some of the small ubiquitin-linked peptides that are a hallmark of Doa4 deficiency are not present in rsp5 mutant cells or after overproduction of a variant ubiquitin modified at Lys 63 (UbK63R). These data suggest that the corresponding peptides are degradation products of Rsp5p substrates and probably of ubiquitin conjugates carrying UbK63 linkages. Doa4p thus appears to be involved in the deubiquitination of endocytosed plasma membrane proteins, some of them carrying UbK63 linkages.

scholarly journals The role of VPS4 in ESCRT-III polymer remodeling

2019 ◽  
Vol 47 (1) ◽  
pp. 441-448 ◽  
Author(s):  
Christophe Caillat ◽  
Sourav Maity ◽  
Nolwenn Miguet ◽  
Wouter H. Roos ◽  
Winfried Weissenhorn
Keyword(s):  
Active Role ◽  
Mechanistic Models ◽  
Membrane Remodeling ◽  
Filament Formation ◽  
Enveloped Viruses ◽  
Endosomal Sorting ◽  
Membrane Fission ◽  
Dynamic Assembly ◽  
Inside Out

Abstract The endosomal sorting complex required for transport-III (ESCRT-III) and VPS4 catalyze a variety of membrane-remodeling processes in eukaryotes and archaea. Common to these processes is the dynamic recruitment of ESCRT-III proteins from the cytosol to the inner face of a membrane neck structure, their activation and filament formation inside or at the membrane neck and the subsequent or concomitant recruitment of the AAA-type ATPase VPS4. The dynamic assembly of ESCRT-III filaments and VPS4 on cellular membranes induces constriction of membrane necks with large diameters such as the cytokinetic midbody and necks with small diameters such as those of intraluminal vesicles or enveloped viruses. The two processes seem to use different sets of ESCRT-III filaments. Constriction is then thought to set the stage for membrane fission. Here, we review recent progress in understanding the structural transitions of ESCRT-III proteins required for filament formation, the functional role of VPS4 in dynamic ESCRT-III assembly and its active role in filament constriction. The recent data will be discussed in the context of different mechanistic models for inside-out membrane fission.

scholarly journals Role of the Endocytic Machinery in the Sorting of Lysosome-associated Membrane Proteins

2005 ◽  
Vol 16 (9) ◽  
pp. 4231-4242 ◽  
Author(s):  
Katy Janvier ◽  
Juan S. Bonifacino
Keyword(s):  
Plasma Membrane ◽  
Coat Protein ◽  
Membrane Proteins ◽  
Adaptor Protein ◽  
The Other ◽  
Sorting Signals ◽  
Efficient Delivery ◽  
Endocytic Machinery

The limiting membrane of the lysosome contains a group of transmembrane glycoproteins named lysosome-associated membrane proteins (Lamps). These proteins are targeted to lysosomes by virtue of tyrosine-based sorting signals in their cytosolic tails. Four adaptor protein (AP) complexes, AP-1, AP-2, AP-3, and AP-4, interact with such signals and are therefore candidates for mediating sorting of the Lamps to lysosomes. However, the role of these complexes and of the coat protein, clathrin, in sorting of the Lamps in vivo has either not been addressed or remains controversial. We have used RNA interference to show that AP-2 and clathrin—and to a lesser extent the other AP complexes—are required for efficient delivery of the Lamps to lysosomes. Because AP-2 is exclusively associated with plasma membrane clathrin coats, our observations imply that a significant population of Lamps traffic via the plasma membrane en route to lysosomes.

scholarly journals Tracking the Fate of Genetically Distinct Vesicular Stomatitis Virus Matrix Proteins Highlights the Role for Late Domains in Assembly

2015 ◽  
Vol 89 (23) ◽  
pp. 11750-11760 ◽  
Author(s):  
Timothy K. Soh ◽  
Sean P. J. Whelan
Keyword(s):  
Plasma Membrane ◽  
Vesicular Stomatitis Virus ◽  
Matrix Protein ◽  
Fluorescent Proteins ◽  
Endosomal Sorting ◽  
Escrt Machinery ◽  
Viral Particles ◽  
The Matrix ◽  
Vesicular Stomatitis ◽  
Late Domains

ABSTRACTVesicular stomatitis virus (VSV) assembly requires condensation of the viral ribonucleoprotein (RNP) core with the matrix protein (M) during budding from the plasma membrane. The RNP core comprises the negative-sense genomic RNA completely coated by the nucleocapsid protein (N) and associated by a phosphoprotein (P) with the large polymerase protein (L). To study the assembly of single viral particles, we tagged M and P with fluorescent proteins. We selected from a library of viruses with insertions in the M gene a replication-competent virus containing a fluorescent M and combined that with our previously described virus containing fluorescent P. Virus particles containing those fusions maintained the same bullet shape appearance as wild-type VSV but had a modest increase in particle length, reflecting the increased genome size. Imaging of the released particles revealed a variation in the amount of M and P assembled into the virions, consistent with a flexible packaging mechanism. We used the recombinants to further study the importance of the late domains in M, which serve to recruit the endosomal sorting complex required for transport (ESCRT) machinery during budding. Mutations in late domains resulted in the accumulation of virions that failed to pinch off from the plasma membrane. Imaging of single virions released from cells that were coinfected with M tagged with enhanced green fluorescent protein and M tagged with mCherry variants in which the late domains of one virus were inactivated by mutation showed a strong bias against the incorporation of the late-domain mutant into the released virions. In contrast, the intracellular expression and membrane association of the two variants were unaltered. These studies provide new tools for imaging particle assembly and enhance our resolution of existing models for assembly of VSV.IMPORTANCEAssembly of vesicular stomatitis virus (VSV) particles requires the separate trafficking of the viral replication machinery, a matrix protein (M) and a glycoprotein, to the plasma membrane. The matrix protein contains a motif termed a “late domain” that engages the host endosomal sorting complex required for transport (ESCRT) machinery to facilitate the release of viral particles. Inactivation of the late domains through mutation results in the accumulation of virions arrested at the point of release. In the study described here, we developed new tools to study VSV assembly by fusing fluorescent proteins to M and to a constituent of the replication machinery, the phosphoprotein (P). We used those tools to show that the late domains of M are required for efficient incorporation into viral particles and that the particles contain a variable quantity of M and P.

Sign in / Sign up

Export Citation Format

Share Document