Multibudded tubules formed by COPII on artificial liposomes

Bacia, Kirsten; Futai, Eugene; Prinz, Simone; Meister, Annette; Daum, Sebastian; Glatte, Daniela; Briggs, John; Schekman, Randy

doi:10.1038/srep00017

Cited by 85 publications

(105 citation statements)

References 30 publications

(51 reference statements)

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“…Our conclusion is that agarose vesicles should not be employed for instance when extracting membrane properties from vesicle deformation (4,35), pore formation by membrane active molecules (8,42,43), protein-induced membrane curvature (44)(45)(46), initial steps in membrane solubilization by detergents (47,48), and vesicle reshaping during changes in the phase state of the bilayer (7,49). On the other hand, studies focusing on membrane properties such as lateral mobility of membrane components and phase separation, or membrane protein reconstitution might still profit from the use of agarose-GUVs.…”

Section: Discussionmentioning

confidence: 96%

Giant Unilamellar Vesicles Formed by Hybrid Films of Agarose and Lipids Display Altered Mechanical Properties

Lira

Dimova

Riske

2014

Biophysical Journal

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Giant unilamellar vesicles (GUVs) are presumably the current most popular biomimetic membrane model. Preparation of GUVs in physiological conditions using the classical electroformation method is challenging. To circumvent these difficulties, a new method was recently reported, by which GUVs spontaneously swell from hybrid films of agarose and lipids. However, agarose is left encapsulated in the vesicles in different amounts. In this work, we thoroughly characterize the mechanical properties of these agarose-GUVs in response to electric pulses, which induce vesicle deformation and can lead to membrane poration. We show that the relaxation dynamics of deformed vesicles, both in the presence and absence of poration, is significantly slowed down for agarose-GUVs when compared to agarose-free GUVs. In the presence of poration, agarose polymers prevent complete pore closure and lead to high membrane permeability. A fraction of the vesicles were found to encapsulate agarose in the form of a gel-like meshwork. These vesicles rupture and open up after electroporation and the meshwork is expelled through a macropore. When the agarose-GUVs are heated above the melting temperature of agarose for 2 h before use, vesicle response is (partially) recovered due to substantial release of encapsulated agarose during temperature treatment. Our findings reveal potential artifactual behavior of agarose-GUVs in processes involving morphological changes in the membrane as well as poration.

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Section: Discussionmentioning

confidence: 96%

Giant Unilamellar Vesicles Formed by Hybrid Films of Agarose and Lipids Display Altered Mechanical Properties

Lira

Dimova

Riske

2014

Biophysical Journal

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“…However, coating of a membrane patch to promote curvature and concentrate cargo at the tip of a transiently produced tubule is a distinct possibility. It has been shown in vitro that COPII components can tubulate liposome membrane (Bacia et al, 2011), and it has even been suggested that COPII coat components have sufficient flexibility to form 300-nm tubular structures that can accommodate large filamentous cargo such as procollagen fibrils (Miller and Schekman, 2013). Such tubes could easily span the narrow greater-than-300-nm interface between ER and cisGolgi in plants.…”

Section: Federica Brandizzi: the Secretory Units Model For Er Proteinmentioning

confidence: 99%

Vesicles versus Tubes: Is Endoplasmic Reticulum-Golgi Transport in Plants Fundamentally Different from Other Eukaryotes?

et al. 2015

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“…Alternatively, TANGO1/cTAGE5 might constitute machinery that switches COPII coat assembly from small spherical vesicles to large carriers, but such a mechanism has not been explored to date. Important in this respect is the observation of tubular COPII carriers with dimensions commensurate with procollagen cargo; such tubules form, along with small vesicles, in budding reactions in vivo and in vitro (14)(15)(16). COPII-coated tubules are observed as straight-sided tubes (17), or with a beads-ona-string appearance in which regular constrictions may arise from aborted attempts at membrane fission (14,16).…”

mentioning

confidence: 99%

“…Important in this respect is the observation of tubular COPII carriers with dimensions commensurate with procollagen cargo; such tubules form, along with small vesicles, in budding reactions in vivo and in vitro (14)(15)(16). COPII-coated tubules are observed as straight-sided tubes (17), or with a beads-ona-string appearance in which regular constrictions may arise from aborted attempts at membrane fission (14,16). Whereas vesicles contain a Sec23/24 inner coat and a self-assembled Sec13/31 cage with isometric (cubic) symmetry, tubules are coated with a distinctive, close-packed Sec23/24 helical lattice and a rhomboidal Sec13/31 cage (17).…”

mentioning

confidence: 99%

TANGO1/cTAGE5 receptor as a polyvalent template for assembly of large COPII coats

Goldberg

2016

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

101

159

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The supramolecular cargo procollagen is loaded into coat protein complex II (COPII)-coated carriers at endoplasmic reticulum (ER) exit sites by the receptor molecule TANGO1/cTAGE5. Electron microscopy studies have identified a tubular carrier of suitable dimensions that is molded by a distinctive helical array of the COPII inner coat protein Sec23/24•Sar1; the helical arrangement is absent from canonical COPII-coated small vesicles. In this study, we combined X-ray crystallographic and biochemical analysis to characterize the association of TANGO1/cTAGE5 with COPII proteins. The affinity for Sec23 is concentrated in the proline-rich domains (PRDs) of TANGO1 and cTAGE5, but Sec23 recognizes merely a PPP motif. The PRDs contain repeated PPP motifs separated by proline-rich linkers, so a single TANGO1/cTAGE5 receptor can bind multiple copies of coat protein in a close-packed array. We propose that TANGO1/cTAGE5 promotes the accretion of inner coat proteins to the helical lattice. Furthermore, we show that PPP motifs in the outer coat protein Sec31 also bind to Sec23, suggesting that stepwise COPII coat assembly will ultimately displace TANGO1/cTAGE5 and compartmentalize its operation to the base of the growing COPII tubule.vesicle traffic | coat protein | procollagen T he coat protein complex II (COPII)-coated vesicles transport secretory and plasma membrane proteins from the endoplasmic reticulum (ER). COPII vesicle budding involves a stepwise assembly reaction: Membrane-bound Sar1-GTP recruits Sec23/24 to form the inner coat complex that, in turn, recruits the Sec13/31 outer coat protein (1). Sec13/31 self-assembles into a polyhedron, and in the process, it sculpts the ER membrane into a bud, producing a COPII-coated vesicle with a diameter of ∼60 nm (2-4).Small cargo molecules are captured during the budding reaction through mechanisms that are well established (5). However, the formation of canonical 60-nm COPII vesicles cannot explain the packaging of large cargos, such as the procollagen fibril with a length of 300-400 nm. Procollagen follows the conventional route of secretion taken by other extracellular proteins, and its ER export evidently depends on COPII carriers because mutations in genes encoding COPII proteins result in collagen secretion blockade, impaired extracellular matrix deposition, and abnormal craniofacial development (6-8). A key discovery was the identification of the receptor TANGO1 and its coreceptor cTAGE5 as ER-localized machinery for loading procollagen into COPII carriers (9, 10). TANGO1 has a luminal SH3 domain shown to interact with collagen VII and a cytosolic domain that interacts with Sec23/24. Both TANGO1 and cTAGE5 are required for collagen export from the ER (9, 10). The TANGO1 knockout mouse has generalized defects in extracellular matrix formation, owing to a block in ER export of multiple collagen types (11).Recent research has implicated post-ER membranes in TANGO1-mediated carrier formation (12, 13); however, the mechanism of action of TANGO1/cTAGE5 in procollagen export...

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Multibudded tubules formed by COPII on artificial liposomes

Cited by 85 publications

References 30 publications

Giant Unilamellar Vesicles Formed by Hybrid Films of Agarose and Lipids Display Altered Mechanical Properties

Giant Unilamellar Vesicles Formed by Hybrid Films of Agarose and Lipids Display Altered Mechanical Properties

Vesicles versus Tubes: Is Endoplasmic Reticulum-Golgi Transport in Plants Fundamentally Different from Other Eukaryotes?

TANGO1/cTAGE5 receptor as a polyvalent template for assembly of large COPII coats

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