A structure of the COPI coat and the role of coat proteins in membrane vesicle assembly

Dodonova, S.O.; Diestelkoetter-Bachert, P.; Appen, Alexander von; Hagen, Wim J. H.; Beck, Rainer; Beck, Martin; Wieland, Felix; Briggs, John

doi:10.1126/science.aab1121

Cited by 158 publications

(205 citation statements)

References 67 publications

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“…The hyper-open conformation of coatomer, in which δ-COP MHD is on the very outside of the coat away from the membrane, would be maintained in the vesicle coat as long as coatomer was bound to Arf1:GTP. After nucleotide hydrolysis and Arf1:GDP disengagement, the F-subcomplex likely would revert to a more closed form; however, because of the COPI B-subcomplex binding to KKxx and KxKxx transmembrane cargoes (29)(30)(31), the coat should not dissociate from the vesicle surface immediately (5). Assuming that the F-subcomplex adopts a closed conformation similar to that of a cytosolic AP complex, modeling suggests that the Wx n (1)(2)(3)(4)(5)(6) [WF] binding site on δ-COP should be accessible when the F-subcomplex is closed (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…However, the open form of F-subcomplexes attached to a membrane in a coat recently has been demonstrated to be even more extreme than the open conformation of AP complexes (27,28) and now is referred to as "hyper-open" (29). The hyper-open conformation of coatomer, in which δ-COP MHD is on the very outside of the coat away from the membrane, would be maintained in the vesicle coat as long as coatomer was bound to Arf1:GTP.…”

Section: Discussionmentioning

confidence: 99%

“…Therefore one intriguing possibility is that the high global negative charge of δ-COP may contribute to the specificity of target membrane fusion of COPI-coated vesicles that in δ-COP could inhibit close apposition and hence fusion with more negatively charged membranes such as the late Golgi/TGN, but not inhibit contact with the comparatively uncharged membranes of the cis-Golgi and ER. Such a mechanism could impart retrograde directionality to COPI vesicle transport through the Golgi toward the ER and also might involve the α-COP CTD /e-COP subcomplex, which likewise is both highly negatively charged (36,37) and located on the outside of the COPI coat (29). It should be noted that for such a scenario to operate, a significant proportion of coatomer must indeed remain associated with vesicles right up to their docking step to allow Dsl1 complex-mediated tethering of COPI-coated vesicles to occur (5,15).…”

Section: Discussionmentioning

confidence: 99%

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Structural basis for the binding of tryptophan-based motifs by δ-COP

Suckling

Poon

Travis

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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Coatomer consists of two subcomplexes: the membrane-targeting, ADP ribosylation factor 1 (Arf1):GTP-binding βγδζ-COP F-subcomplex, which is related to the adaptor protein (AP) clathrin adaptors, and the cargo-binding αβ'e-COP B-subcomplex. We present the structure of the C-terminal μ-homology domain of the yeast δ-COP subunit in complex with the WxW motif from its binding partner, the endoplasmic reticulum-localized Dsl1 tether. The motif binds at a site distinct from that used by the homologous AP μ subunits to bind YxxΦ cargo motifs with its two tryptophan residues sitting in compatible pockets. We also show that the Saccharomyces cerevisiae Arf GTPase-activating protein (GAP) homolog Gcs1p uses a related WxxF motif at its extreme C terminus to bind to δ-COP at the same site in the same way. Mutations designed on the basis of the structure in conjunction with isothermal titration calorimetry confirm the mode of binding and show that mammalian δ-COP binds related tryptophan-based motifs such as that from ArfGAP1 in a similar manner. We conclude that δ-COP subunits bind Wx n(1-6) [WF] motifs within unstructured regions of proteins that influence the lifecycle of COPI-coated vesicles; this conclusion is supported by the observation that, in the context of a sensitizing domain deletion in Dsl1p, mutating the tryptophan-based motif-binding site in yeast causes defects in both growth and carboxypeptidase Y trafficking/processing. C OPI vesicles mediate retrograde trafficking from the Golgi to the endoplasmic reticulum (ER) and within the Golgi (reviewed in refs. 1-3). The COPI vesicle coat consists of two major components, coatomer and the small GTPase ADP ribosylation factor 1 (Arf1). Coatomer is an ∼600 kDa heteroheptameric complex consisting of two linked subcomplexes, the βγδζ-COP F-subcomplex and the αβ'e-COP B-subcomplex, all conserved from yeast to humans.Recent studies have led to a model for COPI-coated vesicle formation in which the F-subcomplex functions as a traditional Arf1:GTP effector but with two membrane-attached Arf1:GTP molecules binding to quasi-equivalent sites on a single F-subcomplex, recruiting F-subcomplex and its associated B-subcomplex onto the membrane en bloc (4). Once the vesicle has budded from its donor membrane, an Arf GTPase-activating protein (ArfGAP) catalyzes the hydrolysis of GTP on Arf1, and the Arf1:GDP dissociates from the membrane, followed later by the dissociation of the coatomer complex that was bound to the transport vesicle (5). ArfGAPs also have been proposed to function at different stages in vesicle biogenesis, both as terminators and, during an earlier cargoediting step, as effectors (reviewed in depth in ref. 6). In the final stages of its life, a COPI-coated vesicle docks with the ER via the Dsl1-tethering complex, completes uncoating, and finally undergoes SNARE-mediated fusion with the ER (7-9).The two main ArfGAPs associated with COPI-dependent retrograde transport in yeast are Gcs1p and Glo3p. These proteins can substitute for one another, at least partially,...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Structural basis for the binding of tryptophan-based motifs by δ-COP

Suckling

Poon

Travis

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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“…ER-derived cargo is first shuttled to the ERGIC in a coat protein (COP) Ⅱ-dependent step and subsequently to the Golgi apparatus in a second vesicular transport step involving COPⅠ-coated vesicles, RAB and ARF GTPases, as well as cytoskeletal networks; incoming vesicles can also be recycled to the ER in a COPⅠ-mediated process [28] . The ERGIC contributes to the concentration, folding, and quality control of newly synthesized proteins and is required for the production of several viral pathogens [29] .…”

Section: Introductionmentioning

confidence: 99%

Assembly and release of infectious hepatitis C virus involving unusual organization of the secretory pathway

Triyatni

Berger

Saunier

2016

WJH

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Institutional review board statement: Approved the use of serum IgG of a patient cured from an HCV infection for in vitro studies (Hôpital and Institut Cochin, Paris).Institutional animal care and use committee statement: Not applicable.Conflict-of-interest statement: Saunier B, Triyatni M and Berger EA are co-inventors on NIH-owned patent #US 9052321 B2 on the HCV particle production system. Triyatni M et al . Unusual secretory pathway of hepatitis C virus in thin section transmission electron microscopy. These findings were compared with the JFH-1 strain/Huh-7.5 cell model. RESULTS:We found that CANX was necessary for the production of HCV particles by BHK-WNV cells. This process involved the recruitment of a subset of HCV proteins, detected by immunoglobulin of an HCV-cured patient, in a compartment of rearranged membranes bypassing the endoplasmic reticulum-Golgi intermediary compartment and surrounded by mitochondria. It also involved the maturation of N-linked glycans on HCV envelope proteins, which was required for assembly and/or secretion of HCV particles. The formation of this specialized compartment required RAB1; upon expression of HCV structural genes, this compartment developed large vesicles with viral particles. RAB1 and alpha-tubulin were required for the release of HCV particles. These cellular factors were also involved in the production of HCVcc in the JFH-1 strain/Huh-7.5 cell system, which involves HCV RNA replication. The secretion of HCV particles by BHK-WNV cells presents similarities with a pathway involving caspase-1; a caspase-1 inhibitor was found to suppress the production of HCV particles from a full-length genome. CONCLUSION:Prior activity of the WNV subgenomic replicon in BHK-21 cells promoted re-wiring of host factors for the assembly and release of infectious HCV in a caspase-1-dependent mechanism. Core tip: Our system for production of authentic infectious hepatitis C virus (HCV) in non-humanized, nonhepatic cells involves the rearrangement of inner cellular membranes triggered by the replication of flaviviruses. The present results suggest that this feature relies on the re-wiring of host factors that usually contribute to the secretion of glycoproteins to generate an unusual secretory pathway. This model offers a new way to study the properties of free HCV particles, i.e. , independently from lipoproteins.Triyatni M, Berger EA, Saunier B. Assembly and release of infectious hepatitis C virus involving unusual organization of the secretory pathway.

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“…To improve the signals and resolution, repetitive molecular features in a 3D tomogram can be further extracted computationally and subjected to averaging and classification using methods similar to those employed in single particle analysis (Asano et al, 2016;Beck & Baumeister, 2016). These methods, called subtomogram averaging, provided valuable insights into biological phenomena such as HIV maturation (Mattei et al, 2016;Schur et al, 2014Schur et al, , 2016, nuclear pore structures (Beck & Glavy, 2014;Beck et al, 2007;Bui et al, 2013), coat protein complex I (Dodonova et al, 2015(Dodonova et al, , 2017, and ribosometranslocation machinery (Pfeffer et al, 2015). However, a major drawback of these Cryo-electron tomography and subtomogram averaging technique is their limited resolution.…”

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confidence: 99%

The Nobel Prize in Chemistry 2017: High-Resolution Cryo-Electron Microscopy

Chung

Kim

2017

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. They all contributed to the development of a Cryo-electron microscopy (EM) technique for determining the highresolution structures of biomolecules in solution, particularly without crystal and with much less amount of biomolecules than X-ray crystallography. In this brief commentary, we address the major advances made by these three Nobel laureates as well as the current status and future prospects of this Cryo-EM technique.

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A structure of the COPI coat and the role of coat proteins in membrane vesicle assembly

Cited by 158 publications

References 67 publications

Structural basis for the binding of tryptophan-based motifs by δ-COP

Structural basis for the binding of tryptophan-based motifs by δ-COP

Assembly and release of infectious hepatitis C virus involving unusual organization of the secretory pathway

The Nobel Prize in Chemistry 2017: High-Resolution Cryo-Electron Microscopy

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