1
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Taylor RJ, Tagiltsev G, Briggs JAG. The structure of COPI vesicles and regulation of vesicle turnover. FEBS Lett 2023; 597:819-835. [PMID: 36513395 DOI: 10.1002/1873-3468.14560] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 11/30/2022] [Accepted: 12/02/2022] [Indexed: 12/15/2022]
Abstract
COPI-coated vesicles mediate transport between Golgi stacks and retrograde transport from the Golgi to the endoplasmic reticulum. The COPI coat exists as a stable heptameric complex in the cytosol termed coatomer and is recruited en bloc to the membrane for vesicle formation. Recruitment of COPI onto membranes is mediated by the Arf family of small GTPases, which, in their GTP-bound state, bind both membrane and coatomer. Arf GTPases also influence cargo selection, vesicle scission and vesicle uncoating. Guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs) regulate nucleotide binding by Arf GTPases. To understand the mechanism of COPI-coated vesicle trafficking, it is necessary to characterize the interplay between coatomer and Arf GTPases and their effectors. It is also necessary to understand interactions between coatomer and cargo, cargo adaptors/receptors and tethers facilitating binding to the target membrane. Here, we summarize current knowledge of COPI coat protein structure; we describe how structural and biochemical studies contributed to this knowledge; we review mechanistic insights into COPI vesicle biogenesis and disassembly; and we discuss the potential to answer open questions in the field.
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Affiliation(s)
- Rebecca J Taylor
- Department of Cell and Virus Structure, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Grigory Tagiltsev
- Department of Cell and Virus Structure, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - John A G Briggs
- Department of Cell and Virus Structure, Max Planck Institute of Biochemistry, Martinsried, Germany
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2
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Arakel EC, Huranova M, Estrada AF, Rau EM, Spang A, Schwappach B. Dissection of GTPase-activating proteins reveals functional asymmetry in the COPI coat of budding yeast. J Cell Sci 2019; 132:jcs.232124. [PMID: 31331965 PMCID: PMC6737914 DOI: 10.1242/jcs.232124] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 07/12/2019] [Indexed: 12/11/2022] Open
Abstract
The Arf GTPase controls formation of the COPI vesicle coat. Recent structural models of COPI revealed the positioning of two Arf1 molecules in contrasting molecular environments. Each of these pockets for Arf1 is expected to also accommodate an Arf GTPase-activating protein (ArfGAP). Structural evidence and protein interactions observed between isolated domains indirectly suggest that each niche preferentially recruits one of the two ArfGAPs known to affect COPI, i.e. Gcs1/ArfGAP1 and Glo3/ArfGAP2/3, although only partial structures are available. The functional role of the unique non-catalytic domain of either ArfGAP has not been integrated into the current COPI structural model. Here, we delineate key differences in the consequences of triggering GTP hydrolysis through the activity of one versus the other ArfGAP. We demonstrate that Glo3/ArfGAP2/3 specifically triggers Arf1 GTP hydrolysis impinging on the stability of the COPI coat. We show that the Snf1 kinase complex, the yeast homologue of AMP-activated protein kinase (AMPK), phosphorylates the region of Glo3 that is crucial for this effect and, thereby, regulates its function in the COPI-vesicle cycle. Our results revise the model of ArfGAP function in the molecular context of COPI. This article has an associated First Person interview with the first author of the paper. Highlighted Article: The regulatory domain of the COPI-associated ArfGAP Glo3 can stabilize the COPI coat. GTP hydrolysis is necessary to resolve the stabilised state. This mechanism is regulated by phosphorylation.
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Affiliation(s)
- Eric C Arakel
- Department of Molecular Biology, Universitätsmedizin Göttingen, Humboldtallee 23, 37073 Göttingen, Germany
| | - Martina Huranova
- Growth and Development, Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland.,Laboratory of Adaptive Immunity, Institute of Molecular Genetics of the Czech Academy of Sciences, Videnska 1083, 142 20 Prague 4, Czech Republic
| | - Alejandro F Estrada
- Growth and Development, Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | - E-Ming Rau
- Growth and Development, Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | - Anne Spang
- Growth and Development, Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | - Blanche Schwappach
- Department of Molecular Biology, Universitätsmedizin Göttingen, Humboldtallee 23, 37073 Göttingen, Germany .,Max-Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
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3
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Assembly-hub function of ER-localized SNARE proteins in biogenesis of tombusvirus replication compartment. PLoS Pathog 2018; 14:e1007028. [PMID: 29746582 PMCID: PMC5963807 DOI: 10.1371/journal.ppat.1007028] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 05/22/2018] [Accepted: 04/13/2018] [Indexed: 01/28/2023] Open
Abstract
Positive-strand RNA viruses assemble numerous membrane-bound viral replicase complexes within large replication compartments to support their replication in infected cells. Yet the detailed mechanism of how given subcellular compartments are subverted by viruses is incompletely understood. Although, Tomato bushy stunt virus (TBSV) uses peroxisomal membranes for replication, in this paper, we show evidence that the ER-resident SNARE (soluble NSF attachment protein receptor) proteins play critical roles in the formation of active replicase complexes in yeast model host and in plants. Depletion of the syntaxin 18-like Ufe1 and Use1, which are components of the ER SNARE complex in the ERAS (ER arrival site) subdomain, in yeast resulted in greatly reduced tombusvirus accumulation. Over-expression of a dominant-negative mutant of either the yeast Ufe1 or the orthologous plant Syp81 syntaxin greatly interferes with tombusvirus replication in yeast and plants, thus further supporting the role of this host protein in tombusvirus replication. Moreover, tombusvirus RNA replication was low in cell-free extracts from yeast with repressed Ufe1 or Use1 expression. We also present evidence for the mislocalization of the tombusviral p33 replication protein to the ER membrane in Ufe1p-depleted yeast cells. The viral p33 replication protein interacts with both Ufe1p and Use1p and co-opts them into the TBSV replication compartment in yeast and plant cells. The co-opted Ufe1 affects the virus-driven membrane contact site formation, sterol-enrichment at replication sites, recruitment of several pro-viral host factors and subversion of the Rab5-positive PE-rich endosomes needed for robust TBSV replication. In summary, we demonstrate a critical role for Ufe1 and Use1 SNARE proteins in TBSV replication and propose that the pro-viral functions of Ufe1 and Use1 are to serve as assembly hubs for the formation of the extensive TBSV replication compartments in cells. Altogether, these findings point clearly at the ERAS subdomain of ER as a critical site for the biogenesis of the TBSV replication compartment. Viral replication organelles are formed in subcellular compartments during positive-strand RNA virus infections to support robust virus replication. TBSV induces multivesicular body-like structures consisting of aggregated peroxisomes. However, endoplasmic reticulum (ER) and early endosomal proteins and membranes also contribute to the biogenesis of the replication compartment. The authors show that the syntaxin 18-like Ufe1 and Use1 ER SNARE proteins, which are present in ER subdomains called ERAS (ER arrival site), are necessary for the formation of the viral replication organelles. By binding to the p33 replication protein of TBSV, Ufe1 and Use1 serve as an assembly hub for biogenesis of the replication compartment and facilitating the transfer of phospholipids and sterols to the growing sites of viral replication. The advantage of co-opting ER resident SNAREs could be that these proteins constitute very active ER subdomains (ERAS), which might be especially suitable for generation of the extensive membranous viral replication compartment.
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4
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Abstract
The coat protein complex I (COPI) allows the precise sorting of lipids and proteins between Golgi cisternae and retrieval from the Golgi to the ER. This essential role maintains the identity of the early secretory pathway and impinges on key cellular processes, such as protein quality control. In this Cell Science at a Glance and accompanying poster, we illustrate the different stages of COPI-coated vesicle formation and revisit decades of research in the context of recent advances in the elucidation of COPI coat structure. By calling attention to an array of questions that have remained unresolved, this review attempts to refocus the perspectives of the field.
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Affiliation(s)
- Eric C Arakel
- Department of Molecular Biology, Universitätsmedizin Göttingen, Humboldtallee 23, 37073 Göttingen, Germany
| | - Blanche Schwappach
- Department of Molecular Biology, Universitätsmedizin Göttingen, Humboldtallee 23, 37073 Göttingen, Germany .,Max-Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
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5
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Zhang S, Liu X, Li L, Yu R, He J, Zhang H, Zheng X, Wang P, Zhang Z. The ArfGAP protein MoGlo3 regulates the development and pathogenicity of Magnaporthe oryzae. Environ Microbiol 2017; 19:3982-3996. [PMID: 28504350 DOI: 10.1111/1462-2920.13798] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Accepted: 05/09/2017] [Indexed: 01/21/2023]
Abstract
The ADP ribosylation factor (Arf) and the coat protein complex I (COPI) are involved in vesicle transport. Together with GTPase-activating proteins (ArfGAPs) and guanine exchange factors (ArfGEFs) that regulate the activity of Arf, they govern vesicle formation, COPI trafficking and the maintenance of the Golgi complex. In an ongoing effort to study the role of membrane trafficking in pathogenesis of the rice blast fungus Magnaporthe oryzae, we identified MoGlo3 as an ArfGAP protein that is homologous to Glo3p of the budding yeast Saccharomyces cerevisiae. As suspected, MoGlo3 partially complements the function of yeast Glo3p. Consistent with findings in S. cerevisiae, MoGlo3 is localized to the Golgi, and that the localization is dependent on the conserved BoCCS domain. We found that MoGlo3 is highly expressed during conidiation and early infection stages and is required for vegetative growth, conidial production and sexual development. We further found that the ΔMoglo3 mutant is defective in endocytosis, scavenging of the reactive oxygen species, and in the response to endoplasmic reticulum (ER) stress. The combined effects result in failed appressorium function and decreased pathogenicity. Moreover, we provided evidence showing that the domains including the GAP, BoCCS and GRM are all important for normal MoGlo3 functions. Our studies further illustrate the importance of normal membrane trafficking in the physiology and pathogenicity of the rice blast fungus.
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Affiliation(s)
- Shengpei Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, People's Republic of China
| | - Xiu Liu
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, People's Republic of China
| | - Lianwei Li
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, People's Republic of China
| | - Rui Yu
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, People's Republic of China
| | - Jialiang He
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, People's Republic of China
| | - Haifeng Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, People's Republic of China
| | - Xiaobo Zheng
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, People's Republic of China
| | - Ping Wang
- Departments of Pediatrics and Microbiology, Immunology, and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
| | - Zhengguang Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing 210095, People's Republic of China
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6
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Dodonova SO, Aderhold P, Kopp J, Ganeva I, Röhling S, Hagen WJH, Sinning I, Wieland F, Briggs JAG. 9Å structure of the COPI coat reveals that the Arf1 GTPase occupies two contrasting molecular environments. eLife 2017. [PMID: 28621666 PMCID: PMC5482573 DOI: 10.7554/elife.26691] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
COPI coated vesicles mediate trafficking within the Golgi apparatus and between the Golgi and the endoplasmic reticulum. Assembly of a COPI coated vesicle is initiated by the small GTPase Arf1 that recruits the coatomer complex to the membrane, triggering polymerization and budding. The vesicle uncoats before fusion with a target membrane. Coat components are structurally conserved between COPI and clathrin/adaptor proteins. Using cryo-electron tomography and subtomogram averaging, we determined the structure of the COPI coat assembled on membranes in vitro at 9 Å resolution. We also obtained a 2.57 Å resolution crystal structure of βδ-COP. By combining these structures we built a molecular model of the coat. We additionally determined the coat structure in the presence of ArfGAP proteins that regulate coat dissociation. We found that Arf1 occupies contrasting molecular environments within the coat, leading us to hypothesize that some Arf1 molecules may regulate vesicle assembly while others regulate coat disassembly. DOI:http://dx.doi.org/10.7554/eLife.26691.001
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Affiliation(s)
- Svetlana O Dodonova
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany.,Molecular Biology Department, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Patrick Aderhold
- Heidelberg University Biochemistry Center, Heidelberg University, Heidelberg, Germany
| | - Juergen Kopp
- Heidelberg University Biochemistry Center, Heidelberg University, Heidelberg, Germany
| | - Iva Ganeva
- Heidelberg University Biochemistry Center, Heidelberg University, Heidelberg, Germany
| | - Simone Röhling
- Heidelberg University Biochemistry Center, Heidelberg University, Heidelberg, Germany
| | - Wim J H Hagen
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Irmgard Sinning
- Heidelberg University Biochemistry Center, Heidelberg University, Heidelberg, Germany
| | - Felix Wieland
- Heidelberg University Biochemistry Center, Heidelberg University, Heidelberg, Germany
| | - John A G Briggs
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany.,Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany.,MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
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7
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Spang A. Retrograde traffic from the Golgi to the endoplasmic reticulum. Cold Spring Harb Perspect Biol 2013; 5:5/6/a013391. [PMID: 23732476 DOI: 10.1101/cshperspect.a013391] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Proteins to be secreted are transported from the endoplasmic reticulum (ER) to the Golgi apparatus. The transport of these proteins requires the localization and activity of proteins that create ER exit sites, coat proteins to collect cargo and to reshape the membrane into a transport container, and address labels--SNARE proteins--to target the vesicles specifically to the Golgi apparatus. In addition some proteins may need export chaperones or export receptors to enable their exit into transport vesicles. ER export factors, SNAREs, and misfolded Golgi-resident proteins must all be retrieved from the Golgi to the ER again. This retrieval is also part of the organellar homeostasis pathway essential to maintaining the identity of the ER and of the Golgi apparatus. In this review, I will discuss the different processes in retrograde transport from the Golgi to the ER and highlight the mechanistic insights we have obtained in the last couple of years.
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Affiliation(s)
- Anne Spang
- University of Basel, Biozentrum, Growth & Development, Klingelbergstrasse 70, 4056 Basel, Switzerland.
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8
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Delic M, Valli M, Graf AB, Pfeffer M, Mattanovich D, Gasser B. The secretory pathway: exploring yeast diversity. FEMS Microbiol Rev 2013; 37:872-914. [PMID: 23480475 DOI: 10.1111/1574-6976.12020] [Citation(s) in RCA: 140] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Revised: 02/14/2013] [Accepted: 02/17/2013] [Indexed: 12/11/2022] Open
Abstract
Protein secretion is an essential process for living organisms. In eukaryotes, this encompasses numerous steps mediated by several hundred cellular proteins. The core functions of translocation through the endoplasmic reticulum membrane, primary glycosylation, folding and quality control, and vesicle-mediated secretion are similar from yeasts to higher eukaryotes. However, recent research has revealed significant functional differences between yeasts and mammalian cells, and even among diverse yeast species. This review provides a current overview of the canonical protein secretion pathway in the model yeast Saccharomyces cerevisiae, highlighting differences to mammalian cells as well as currently unresolved questions, and provides a genomic comparison of the S. cerevisiae pathway to seven other yeast species where secretion has been investigated due to their attraction as protein production platforms, or for their relevance as pathogens. The analysis of Candida albicans, Candida glabrata, Kluyveromyces lactis, Pichia pastoris, Hansenula polymorpha, Yarrowia lipolytica, and Schizosaccharomyces pombe reveals that many - but not all - secretion steps are more redundant in S. cerevisiae due to duplicated genes, while some processes are even absent in this model yeast. Recent research obviates that even where homologous genes are present, small differences in protein sequence and/or differences in the regulation of gene expression may lead to quite different protein secretion phenotypes.
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Affiliation(s)
- Marizela Delic
- Department of Biotechnology, University of Natural Resources and Life Sciences (BOKU), Vienna, Austria; Austrian Centre of Industrial Biotechnology (ACIB GmbH), Vienna, Austria
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9
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Tu L, Chen L, Banfield DK. A conserved N-terminal arginine-motif in GOLPH3-family proteins mediates binding to coatomer. Traffic 2012; 13:1496-507. [PMID: 22889169 DOI: 10.1111/j.1600-0854.2012.01403.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Revised: 08/05/2012] [Accepted: 08/13/2012] [Indexed: 01/08/2023]
Abstract
Vps74p, a member of the GOLPH3 protein family, binds directly to coatomer and the cytoplasmic tails of a subset of Golgi-resident glycosyltransferases to mediate their Golgi retention. We identify a cluster of arginine residues at the N-terminal end of GOLPH3 proteins that are necessary and sufficient to mediate coatomer binding. While loss of coatomer binding renders Vps74p non-functional for glycosyltransferase retention, the Golgi membrane-binding capabilities of the mutant protein are not significantly reduced. We establish that the oligomerization status and phosphatidylinositol-4-phosphate-binding properties of Vps74p largely account for the membrane-binding capacity of the protein and identify an Arf1p-Vps74p interaction as a potential contributing factor in Vps74p Golgi membrane association.
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Affiliation(s)
- Linna Tu
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, SAR of China
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10
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Stefano G, Renna L, Rossi M, Azzarello E, Pollastri S, Brandizzi F, Baluska F, Mancuso S. AGD5 is a GTPase-activating protein at the trans-Golgi network. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2010; 64:790-799. [PMID: 21105926 DOI: 10.1111/j.1365-313x.2010.04369.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
ARF-GTPases are important proteins that control membrane trafficking events. Their activity is largely influenced by the interplay between guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs), which facilitate the activation or inactivation of ARF-GTPases, respectively. There are 15 predicted proteins that contain an ARF-GAP domain within the Arabidopsis thaliana genome, and these are classified as ARF-GAP domain (AGD) proteins. The function and subcellular distribution of AGDs, including the ability to activate ARF-GTPases in vivo, that remain largely uncharacterized to date. Here we show that AGD5 is localised to the trans-Golgi network (TGN), where it co-localises with ARF1, a crucial GTPase that is involved in membrane trafficking and which was previously shown to be distributed on Golgi and post-Golgi structures of unknown nature. Taking advantage of the in vivo AGD5-ARF1 interaction at the TGN, we show that mutation of an arginine residue that is critical for ARF-GAP activity of AGD5 leads to longer residence of ARF1 on the membranes, as expected if GTP hydrolysis on ARF1 was impaired due to a defective GAP. Our results establish the nature of the post-Golgi compartments in which ARF1 localises, as well as identifying the role of AGD5 in vivo as a TGN-localised GAP. Furthermore, in vitro experiments established the promiscuous interaction between AGD5 and the plasma membrane-localised ADP ribosylation factor B (ARFB), confirming that ARF-GAP specificity for ARF-GTPases within the cell environment may be spatially regulated.
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Affiliation(s)
- Giovanni Stefano
- Department of Plant, Soil and Environmental Science, viale delle Idee, University of Florence, Sesto Fiorentino, FI 50019, Italy.
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11
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The antibiotic gentamicin inhibits specific protein trafficking functions of the Arf1/2 family of GTPases. Antimicrob Agents Chemother 2010; 55:246-54. [PMID: 20956596 DOI: 10.1128/aac.00450-10] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Gentamicin is a highly efficacious antibiotic against Gram-negative bacteria. However, its usefulness in treating infections is compromised by its poorly understood renal toxicity. Toxic effects are also seen in a variety of other organisms. While the yeast Saccharomyces cerevisiae is relatively insensitive to gentamicin, mutations in any one of ∼20 genes cause a dramatic decrease in resistance. Many of these genes encode proteins important for translation termination or specific protein-trafficking complexes. Subsequent inspection of the physical and genetic interactions of the remaining gentamicin-sensitive mutants revealed a network centered on chitin synthase and the Arf GTPases. Further analysis has demonstrated that some conditional arf1 and gea1 alleles make cells hypersensitive to gentamicin under permissive conditions. These results suggest that one consequence of gentamicin exposure is disruption of Arf-dependent protein trafficking.
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12
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Kartberg F, Asp L, Dejgaard SY, Smedh M, Fernandez-Rodriguez J, Nilsson T, Presley JF. ARFGAP2 and ARFGAP3 are essential for COPI coat assembly on the Golgi membrane of living cells. J Biol Chem 2010; 285:36709-20. [PMID: 20858901 DOI: 10.1074/jbc.m110.180380] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Coat protein complex I (COPI) vesicles play a central role in the recycling of proteins in the early secretory pathway and transport of proteins within the Golgi stack. Vesicle formation is initiated by the exchange of GDP for GTP on ARF1 (ADP-ribosylation factor 1), which, in turn, recruits the coat protein coatomer to the membrane for selection of cargo and membrane deformation. ARFGAP1 (ARF1 GTPase-activating protein 1) regulates the dynamic cycling of ARF1 on the membrane that results in both cargo concentration and uncoating for the generation of a fusion-competent vesicle. Two human orthologues of the yeast ARFGAP Glo3p, termed ARFGAP2 and ARFGAP3, have been demonstrated to be present on COPI vesicles generated in vitro in the presence of guanosine 5'-3-O-(thio)triphosphate. Here, we investigate the function of these two proteins in living cells and compare it with that of ARFGAP1. We find that ARFGAP2 and ARFGAP3 follow the dynamic behavior of coatomer upon stimulation of vesicle budding in vivo more closely than does ARFGAP1. Electron microscopy of ARFGAP2 and ARFGAP3 knockdowns indicated Golgi unstacking and cisternal shortening similarly to conditions where vesicle uncoating was blocked. Furthermore, the knockdown of both ARFGAP2 and ARFGAP3 prevents proper assembly of the COPI coat lattice for which ARFGAP1 does not seem to play a major role. This suggests that ARFGAP2 and ARFGAP3 are key components of the COPI coat lattice and are necessary for proper vesicle formation.
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Affiliation(s)
- Fredrik Kartberg
- Department of Medical and Clinical Genetics, Institute of Biomedicine, University of Gothenburg, 405 30 Göteborg, Sweden
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13
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Spang A, Shiba Y, Randazzo PA. Arf GAPs: gatekeepers of vesicle generation. FEBS Lett 2010; 584:2646-51. [PMID: 20394747 DOI: 10.1016/j.febslet.2010.04.005] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2010] [Revised: 03/26/2010] [Accepted: 04/03/2010] [Indexed: 11/17/2022]
Abstract
Arf GAP proteins are a versatile and diverse group of proteins. They control the activity of the GTP-binding proteins of the ARF family by inducing the hydrolysis of GTP that is bound to Arf proteins. The best-studied role of Arf GAPs is in intracellular traffic. In this review, we will focus mainly on the Arf GAPs that play a role in vesicle formation, Arf GAP1, Arf GAP2 and Arf GAP3 and their yeast homologues, Gcs1p and Glo3p. We discuss the roles of Arf GAPs as regulators and effectors for Arf GTP-binding proteins.
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Affiliation(s)
- Anne Spang
- University of Basel, Growth and Development, Biozentrum, Switzerland.
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14
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Schindler C, Rodriguez F, Poon PP, Singer RA, Johnston GC, Spang A. The GAP domain and the SNARE, coatomer and cargo interaction region of the ArfGAP2/3 Glo3 are sufficient for Glo3 function. Traffic 2009; 10:1362-75. [PMID: 19602196 DOI: 10.1111/j.1600-0854.2009.00952.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The ArfGAP Glo3 is required for coat protein I vesicle generation in the Golgi-endoplasmic reticulum (ER) shuttle. The best-understood role of Glo3 is the stimulation of the GTPase activity of Arf1. In this study, we characterized functional domains of the ArfGAP Glo3 and identified an interaction interface for coatomer, SNAREs and cargo in the central region of Glo3 (BoCCS region). The GAP domain together with the BoCCS region is necessary and sufficient for all vital Glo3 functions. Expression of a truncated Glo3 lacking the GAP domain results in a dominant negative growth phenotype in glo3Delta cells at 37 degrees C. This phenotype was alleviated by mutating either the BoCCS region or the Glo3 regulatory motif (GRM), or by overexpression of ER-Golgi SNAREs or the ArfGAP Gcs1. The GRM is not essential for Glo3 function; it may act as an intrinsic sensor coupling GAP activity to SNARE binding to avoid dead-end complex formation at the Golgi membrane. Our data suggest that membrane-interaction modules and cargo-sensing regions have evolved independently in ArfGAP1s versus ArfGAP2/3s.
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Affiliation(s)
- Christina Schindler
- Biozentrum, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland
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15
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Saitoh A, Shin HW, Yamada A, Waguri S, Nakayama K. Three homologous ArfGAPs participate in coat protein I-mediated transport. J Biol Chem 2009; 284:13948-13957. [PMID: 19299515 DOI: 10.1074/jbc.m900749200] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
ArfGAP1 is a prototype of GTPase-activating proteins for ADP-ribosylation factors (ARFs) and has been proposed to be involved in retrograde transport from the Golgi apparatus to the endoplasmic reticulum (ER) by regulating the uncoating of coat protein I (COPI)-coated vesicles. Depletion of ArfGAP1 by RNA interference, however, causes neither a discernible phenotypic change in the COPI localization nor a change in the Golgi-to-ER retrograde transport. Therefore, we also examined ArfGAP2 and ArfGAP3, closely related homologues of ArfGAP1. Cells in which ArfGAP1, ArfGAP2, and ArfGAP3 are simultaneously knocked down show an increase in the GTP-bound ARF level. Furthermore, in these cells proteins resident in or cycling through the cis-Golgi, including ERGIC-53, beta-COP, and GM130, accumulate in the ER-Golgi intermediate compartment, and Golgi-to-ER retrograde transport is blocked. The phenotypes observed in the triple ArfGAP knockdown cells are similar to those seen in beta-COP-depleted cells. Both the triple ArfGAP- and beta-COP-depleted cells accumulate characteristic vacuolar structures that are visible under electron microscope. Furthermore, COPI is concentrated at rims of the vacuolar structures in the ArfGAP-depleted cells. On the basis of these observations, we conclude that ArfGAP1, ArfGAP2, and ArfGAP3 have overlapping roles in regulating COPI function in Golgi-to-ER retrograde transport.
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Affiliation(s)
- Akina Saitoh
- Graduate School of Pharmaceutical Sciences and Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Hye-Won Shin
- Graduate School of Pharmaceutical Sciences and Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan; Career-Path Promotion Unit for Young Life Scientists, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Akane Yamada
- Department of Anatomy and Histology, Fukushima Medical University, School of Medicine, Fukushima City, Fukushima 960-1295, Japan
| | - Satoshi Waguri
- Department of Anatomy and Histology, Fukushima Medical University, School of Medicine, Fukushima City, Fukushima 960-1295, Japan
| | - Kazuhisa Nakayama
- Graduate School of Pharmaceutical Sciences and Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.
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Kliouchnikov L, Bigay J, Mesmin B, Parnis A, Rawet M, Goldfeder N, Antonny B, Cassel D. Discrete determinants in ArfGAP2/3 conferring Golgi localization and regulation by the COPI coat. Mol Biol Cell 2008; 20:859-69. [PMID: 19109418 DOI: 10.1091/mbc.e08-10-1010] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
From yeast to mammals, two types of GTPase-activating proteins, ArfGAP1 and ArfGAP2/3, control guanosine triphosphate (GTP) hydrolysis on the small G protein ADP-ribosylation factor (Arf) 1 at the Golgi apparatus. Although functionally interchangeable, they display little similarity outside the catalytic GTPase-activating protein (GAP) domain, suggesting differential regulation. ArfGAP1 is controlled by membrane curvature through its amphipathic lipid packing sensor motifs, whereas Golgi targeting of ArfGAP2 depends on coatomer, the building block of the COPI coat. Using a reporter fusion approach and in vitro assays, we identified several functional elements in ArfGAP2/3. We show that the Golgi localization of ArfGAP3 depends on both a central basic stretch and a carboxy-amphipathic motif. The basic stretch interacts directly with coatomer, which we found essential for the catalytic activity of ArfGAP3 on Arf1-GTP, whereas the carboxy-amphipathic motif interacts directly with lipid membranes but has minor role in the regulation of ArfGAP3 activity. Our findings indicate that the two types of ArfGAP proteins that reside at the Golgi use a different combination of protein-protein and protein-lipid interactions to promote GTP hydrolysis in Arf1-GTP.
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Affiliation(s)
- Lena Kliouchnikov
- Department of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel
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17
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Weimer C, Beck R, Eckert P, Reckmann I, Moelleken J, Brügger B, Wieland F. Differential roles of ArfGAP1, ArfGAP2, and ArfGAP3 in COPI trafficking. ACTA ACUST UNITED AC 2008; 183:725-35. [PMID: 19015319 PMCID: PMC2582887 DOI: 10.1083/jcb.200806140] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The formation of coat protein complex I (COPI)–coated vesicles is regulated by the small guanosine triphosphatase (GTPase) adenosine diphosphate ribosylation factor 1 (Arf1), which in its GTP-bound form recruits coatomer to the Golgi membrane. Arf GTPase-activating protein (GAP) catalyzed GTP hydrolysis in Arf1 triggers uncoating and is required for uptake of cargo molecules into vesicles. Three mammalian ArfGAPs are involved in COPI vesicle trafficking; however, their individual functions remain obscure. ArfGAP1 binds to membranes depending on their curvature. In this study, we show that ArfGAP2 and ArfGAP3 do not bind directly to membranes but are recruited via interactions with coatomer. In the presence of coatomer, ArfGAP2 and ArfGAP3 activities are comparable with or even higher than ArfGAP1 activity. Although previously speculated, our results now demonstrate a function for coatomer in ArfGAP-catalyzed GTP hydrolysis by Arf1. We suggest that ArfGAP2 and ArfGAP3 are coat protein–dependent ArfGAPs, whereas ArfGAP1 has a more general function.
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Affiliation(s)
- Carolin Weimer
- Heidelberg University Biochemistry Center, Heidelberg, Germany
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18
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Aguilera-Romero A, Kaminska J, Spang A, Riezman H, Muñiz M. The yeast p24 complex is required for the formation of COPI retrograde transport vesicles from the Golgi apparatus. ACTA ACUST UNITED AC 2008; 180:713-20. [PMID: 18283113 PMCID: PMC2265561 DOI: 10.1083/jcb.200710025] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The p24 family members are transmembrane proteins assembled into heteromeric complexes that continuously cycle between the ER and the Golgi apparatus. These cargo proteins were assumed to play a structural role in COPI budding because of their major presence in mammalian COPI vesicles. However, this putative function has not been proved conclusively so far. Furthermore, deletion of all eight yeast p24 family members does not produce severe transport phenotypes, suggesting that the p24 complex is not essential for COPI function. In this paper we provide direct evidence that the yeast p24 complex plays an active role in retrograde transport from Golgi to ER by facilitating the formation of COPI-coated vesicles. Therefore, our results demonstrate that p24 proteins are important for vesicle formation instead of simply being a passive traveler, supporting the model in which cargo together with a small GTPase of the ARF superfamily and coat subunits act as primer for vesicle formation.
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DeRegis CJ, Rahl PB, Hoffman GR, Cerione RA, Collins RN. Mutational analysis of betaCOP (Sec26p) identifies an appendage domain critical for function. BMC Cell Biol 2008; 9:3. [PMID: 18211691 PMCID: PMC2262067 DOI: 10.1186/1471-2121-9-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2007] [Accepted: 01/22/2008] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The appendage domain of the gammaCOP subunit of the COPI vesicle coat bears a striking structural resemblance to adaptin-family appendages despite limited primary sequence homology. Both the gammaCOP appendage domain and an equivalent region on betaCOP contain the FxxxW motif; the conservation of this motif suggested the existence of a functional appendage domain in betaCOP. RESULTS Sequence comparisons in combination with structural prediction tools show that the fold of the COOH-terminus of Sec26p is strongly predicted to closely mimic that of adaptin-family appendages. Deletion of the appendage domain of Sec26p results in inviability in yeast, over-expression of the deletion construct is dominant negative and mutagenesis of this region identifies residues critical for function. The ArfGAP Glo3p was identified via suppression screening as a potential downstream modulator of Sec26p in a manner that is independent of the GAP activity of Glo3p but requires the presence of the COOH-terminal ISS motifs. CONCLUSION Together, these results indicate an essential function for the predicted betaCOP appendage and suggest that both COPI appendages perform a biologically active regulatory role with a structure related to adaptin-family appendage domains.
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Affiliation(s)
- Carol J DeRegis
- Graduate Program in Comparative Biomedical Sciences, Cornell University, Ithaca NY 14853, USA
| | - Peter B Rahl
- Graduate Program in Pharmacology, Cornell University, Ithaca, NY 14853, USA
| | - Gregory R Hoffman
- Graduate Program in Biophysics, Cornell University, Ithaca, NY 14853, USA
| | - Richard A Cerione
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853, USA
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
| | - Ruth N Collins
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853, USA
- Department of Molecular Medicine, Cornell University, C4-109 Veterinary Medical Center, Ithaca, NY 14853, USA
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20
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Abstract
ADP-ribosylation factors (ARFs) are critical regulators of vesicular trafficking pathways and act at multiple intracellular sites. ADP-ribosylation factor-GTPase-activating proteins (ARFGAPs) are proposed to contribute to site-specific regulation. In yeast, two distinct proteins, Glo3p and Gcs1p, together provide overlapping, essential ARFGAP function required for coat protein (COP)-I-dependent trafficking. In mammalian cells, only the Gcs1p orthologue, named ARFGAP1, has been characterized in detail. However, Glo3p is known to make the stronger contribution to COP I traffic in yeast. Here, based on a conserved signature motif close to the carboxy terminus, we identify ARFGAP2 and ARFGAP3 as the human orthologues of yeast Glo3p. By immunofluorescence (IF), ARFGAP2 and ARFGAP3 are closely colocalized with coatomer subunits in NRK cells in the Golgi complex and peripheral punctate structures. In contrast to ARFGAP1, both ARFGAP2 and ARFGAP3 are associated with COP-I-coated vesicles generated from Golgi membranes in the presence of GTP-γ-S in vitro. ARFGAP2 lacking its zinc finger domain directly binds to coatomer. Expression of this truncated mutant (ΔN-ARFGAP2) inhibits COP-I-dependent Golgi-to-endoplasmic reticulum transport of cholera toxin (CTX-K63) in vivo. Silencing of ARFGAP1 or a combination of ARFGAP2 and ARFGAP3 in HeLa cells does not decrease cell viability. However, silencing all three ARFGAPs causes cell death. Our data provide strong evidence that ARFGAP2 and ARFGAP3 function in COP I traffic.
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Affiliation(s)
- Gabriella Frigerio
- Department of Clinical Biochemistry, Cambridge Institute for Medical Research, University of CambridgeHills Road, Cambridge CB2 2XY, United Kingdom
- European Bioinformatics Institute, Wellcome Trust Genome CampusHinxton, Cambridge CB10 1SD, United Kingdom
| | - Neil Grimsey
- Department of Clinical Biochemistry, Cambridge Institute for Medical Research, University of CambridgeHills Road, Cambridge CB2 2XY, United Kingdom
| | - Martin Dale
- Department of Clinical Biochemistry, Cambridge Institute for Medical Research, University of CambridgeHills Road, Cambridge CB2 2XY, United Kingdom
| | - Irina Majoul
- Department of Clinical Biochemistry, Cambridge Institute for Medical Research, University of CambridgeHills Road, Cambridge CB2 2XY, United Kingdom
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of LondonEgham TW20 0EX, United Kingdom
| | - Rainer Duden
- Department of Clinical Biochemistry, Cambridge Institute for Medical Research, University of CambridgeHills Road, Cambridge CB2 2XY, United Kingdom
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of LondonEgham TW20 0EX, United Kingdom
- Rainer Duden,
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