1
|
Tang X, Wang T, Guo Y. Export of polybasic motif-containing secretory proteins BMP8A and SFRP1 from the endoplasmic reticulum is regulated by surfeit locus protein 4. J Biol Chem 2022; 298:102687. [PMID: 36370847 PMCID: PMC9731852 DOI: 10.1016/j.jbc.2022.102687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 10/29/2022] [Accepted: 11/01/2022] [Indexed: 11/11/2022] Open
Abstract
In the conventional secretory pathway, cargo receptors play important roles in exporting newly synthesized secretory proteins from the endoplasmic reticulum (ER). We previously showed that a cargo receptor, surfeit locus protein 4 (SURF4), promotes ER export of a soluble signaling molecule, sonic hedgehog, via recognizing the polybasic residues within its Cardin-Weintraub motif. In addition to sonic hedgehog, we found 30 more secretory proteins containing the polybasic motif (K/R)(K/R)(K/R)XX(K/R)(K/R), but whether SURF4 plays a general role in mediating ER export of these secretory proteins is unclear. Here, we analyzed the trafficking of four of these secretory proteins: desert hedgehog, Indian hedgehog, bone morphogenetic protein 8A (BMP8A), and secreted frizzled-related protein 1 (SFRP1). We found that the polybasic motifs contained in these cargo proteins are important for their ER export. Further analyses indicated that the polybasic motifs of BMP8A and SFRP1 interact with the triacidic motif on the predicted first luminal domain of SURF4. These interactions with SURF4 are essential and sufficient for the ER-to-Golgi trafficking of BMP8A and SFRP1. Moreover, we demonstrated that SURF4 localizes at a subpopulation of ER exit sites to regulate the ER export of its clients. Taken together, these results suggest that SURF4 is recruited to specific ER exit sites and plays a general role in capturing polybasic motif-containing secretory cargo proteins through electrostatic interactions.
Collapse
Affiliation(s)
- Xiao Tang
- College of Life Sciences, Anhui Normal University, Wuhu, Anhui, China,Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Tingxuan Wang
- Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Yusong Guo
- Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong, China,Hong Kong University of Science and Technology Shenzhen Research Institute, Shenzhen, China,Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China,For correspondence: Yusong Guo
| |
Collapse
|
2
|
VanWinkle PE, Parish F, Edwards YJK, Sztul E. JAGN1, tetraspanins, and Erv proteins: is common topology indicative of common function in cargo sorting? Am J Physiol Cell Physiol 2020; 319:C667-C674. [PMID: 32783652 DOI: 10.1152/ajpcell.00436.2019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The endoplasmic reticulum protein Jagunal (JAGN1) was first identified as a requirement for Drosophila melanogaster oocyte development. Subsequent studies in human patients linked mutations in JAGN1 to severe congenital neutropenia, as well as a broad range of additional symptoms, suggesting that JAGN1 function is required in many tissues. Moreover, JAGN1 orthologs are found throughout animal and plant phylogeny, suggesting that JAGN1 supports fundamental cellular processes not restricted to egg development or neutrophil function. JAGN1 lacks sequence similarity or recognizable domains other than a coatomer protein complex I-binding motif, and its cellular function is currently unknown. JAGN1 shares a tetraspanning membrane topology with two families of known cargo transporters: the tetraspanins and the endoplasmic reticulum vesicle (Erv) proteins. Herein, we discuss the similarities between JAGN1, tetraspanins, and Ervs and, based on those, suggest a role for JAGN1 in facilitating the traffic of cell-restricted and ubiquitously expressed proteins at the endoplasmic reticulum-Golgi interface.
Collapse
Affiliation(s)
- Peyton E VanWinkle
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Felicia Parish
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Yvonne J K Edwards
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama.,Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama
| | - Elizabeth Sztul
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
| |
Collapse
|
3
|
Lopez S, Perez-Linero AM, Manzano-Lopez J, Sabido-Bozo S, Cortes-Gomez A, Rodriguez-Gallardo S, Aguilera-Romero A, Goder V, Muñiz M. Dual Independent Roles of the p24 Complex in Selectivity of Secretory Cargo Export from the Endoplasmic Reticulum. Cells 2020; 9:cells9051295. [PMID: 32456004 PMCID: PMC7291304 DOI: 10.3390/cells9051295] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 05/18/2020] [Accepted: 05/20/2020] [Indexed: 11/22/2022] Open
Abstract
The cellular mechanisms that ensure the selectivity and fidelity of secretory cargo protein transport from the endoplasmic reticulum (ER) to the Golgi are still not well understood. The p24 protein complex acts as a specific cargo receptor for GPI-anchored proteins by facilitating their ER exit through a specialized export pathway in yeast. In parallel, the p24 complex can also exit the ER using the general pathway that exports the rest of secretory proteins with their respective cargo receptors. Here, we show biochemically that the p24 complex associates at the ER with other cargo receptors in a COPII-dependent manner, forming high-molecular weight multireceptor complexes. Furthermore, live cell imaging analysis reveals that the p24 complex is required to retain in the ER secretory cargos when their specific receptors are absent. This requirement does not involve neither the unfolded protein response nor the retrograde transport from the Golgi. Our results suggest that, in addition to its role as a cargo receptor in the specialized GPI-anchored protein pathway, the p24 complex also plays an independent role in secretory cargo selectivity during its exit through the general ER export pathway, preventing the non-selective bulk flow of native secretory cargos. This mechanism would ensure receptor-regulated cargo transport, providing an additional layer of regulation of secretory cargo selectivity during ER export.
Collapse
Affiliation(s)
- Sergio Lopez
- Department of Cell Biology, University of Seville, 41012 Seville, Spain; (S.L.); (A.M.P.-L.); (J.M.-L.); (S.S.-B.); (A.C.-G.); (S.R.-G.); (A.A.-R.)
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, 41012 Seville, Spain
| | - Ana Maria Perez-Linero
- Department of Cell Biology, University of Seville, 41012 Seville, Spain; (S.L.); (A.M.P.-L.); (J.M.-L.); (S.S.-B.); (A.C.-G.); (S.R.-G.); (A.A.-R.)
| | - Javier Manzano-Lopez
- Department of Cell Biology, University of Seville, 41012 Seville, Spain; (S.L.); (A.M.P.-L.); (J.M.-L.); (S.S.-B.); (A.C.-G.); (S.R.-G.); (A.A.-R.)
| | - Susana Sabido-Bozo
- Department of Cell Biology, University of Seville, 41012 Seville, Spain; (S.L.); (A.M.P.-L.); (J.M.-L.); (S.S.-B.); (A.C.-G.); (S.R.-G.); (A.A.-R.)
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, 41012 Seville, Spain
| | - Alejandro Cortes-Gomez
- Department of Cell Biology, University of Seville, 41012 Seville, Spain; (S.L.); (A.M.P.-L.); (J.M.-L.); (S.S.-B.); (A.C.-G.); (S.R.-G.); (A.A.-R.)
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, 41012 Seville, Spain
| | - Sofia Rodriguez-Gallardo
- Department of Cell Biology, University of Seville, 41012 Seville, Spain; (S.L.); (A.M.P.-L.); (J.M.-L.); (S.S.-B.); (A.C.-G.); (S.R.-G.); (A.A.-R.)
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, 41012 Seville, Spain
| | - Auxiliadora Aguilera-Romero
- Department of Cell Biology, University of Seville, 41012 Seville, Spain; (S.L.); (A.M.P.-L.); (J.M.-L.); (S.S.-B.); (A.C.-G.); (S.R.-G.); (A.A.-R.)
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, 41012 Seville, Spain
| | - Veit Goder
- Department of Genetics, University of Seville, 41012 Seville, Spain;
| | - Manuel Muñiz
- Department of Cell Biology, University of Seville, 41012 Seville, Spain; (S.L.); (A.M.P.-L.); (J.M.-L.); (S.S.-B.); (A.C.-G.); (S.R.-G.); (A.A.-R.)
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, 41012 Seville, Spain
- Correspondence: ; Tel.: +34-954556529
| |
Collapse
|
4
|
Tanabe Y, Arai S, Wada I, Adachi H, Kamakura T, Yoda K, Noda Y. Svp26 facilitates ER exit of mannosyltransferases Mnt2 and Mnt3 in Saccharomyces cerevisiae. J GEN APPL MICROBIOL 2019; 65:180-187. [PMID: 30700649 DOI: 10.2323/jgam.2018.09.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
After being translocated into the ER lumen, membrane and secretory proteins are transported from the ER to the early Golgi by COPII vesicles. Incorporation of these cargo proteins into COPII vesicles are facilitated either by direct interaction of cargo proteins with COPII coat proteins or by ER exit adaptor proteins which mediate the interaction of cargo proteins with COPII coat proteins. Svp26 is one of the ER exit adaptor proteins in yeast Saccharomyces cerevisiae. ER exit of several type II membrane proteins have been reported to be facilitated by Svp26. We demonstrate here that efficient incorporation of Mnt2 and Mnt3 into COPII vesicles is also dependent on the function of Svp26. Mnt2 and Mnt3 are Golgi-localized α-1,3-mannosyltransferases with type II membrane topology involved in protein O-glycosylation. Immunoisolation of the yeast Golgi subcompartments quantitatively showed that Mnt2 and Mnt3 are more abundant in the early Golgi fraction than in the late Golgi fraction. Subcellular fractionation and fluorescence microscopy showed that deletion of the SVP26 gene results in the accumulation of Mnt2 and Mnt3 in ER. Using an in vitro COPII vesicle formation assay, we further demonstrate that Svp26 facilitates incorporation of Mnt2 and Mnt3 into COPII vesicles. Finally, we showed that Mnt2 and Mnt3 were co-immunoprecipitated with Svp26 from digitonin-solubilized membranes. These results indicate that Svp26 functions as an ER exit adaptor protein of Mnt2 and Mnt3.
Collapse
Affiliation(s)
- Yuuki Tanabe
- Department of Biotechnology, The University of Tokyo.,Department of Applied Biological Science, Tokyo University of Science
| | - Seisuke Arai
- Department of Cell Science, Institute of Biomedical Sciences, Fukushima Medical University School of Medicine
| | - Ikuo Wada
- Department of Cell Science, Institute of Biomedical Sciences, Fukushima Medical University School of Medicine
| | - Hiroyuki Adachi
- Department of Biotechnology, The University of Tokyo.,Collaborative Research Institute for Innovative Microbiology, The University of Tokyo
| | - Takashi Kamakura
- Department of Applied Biological Science, Tokyo University of Science
| | - Koji Yoda
- Department of Biotechnology, The University of Tokyo
| | - Yoichi Noda
- Department of Biotechnology, The University of Tokyo.,Collaborative Research Institute for Innovative Microbiology, The University of Tokyo
| |
Collapse
|
5
|
Marinko J, Huang H, Penn WD, Capra JA, Schlebach JP, Sanders CR. Folding and Misfolding of Human Membrane Proteins in Health and Disease: From Single Molecules to Cellular Proteostasis. Chem Rev 2019; 119:5537-5606. [PMID: 30608666 PMCID: PMC6506414 DOI: 10.1021/acs.chemrev.8b00532] [Citation(s) in RCA: 160] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2018] [Indexed: 12/13/2022]
Abstract
Advances over the past 25 years have revealed much about how the structural properties of membranes and associated proteins are linked to the thermodynamics and kinetics of membrane protein (MP) folding. At the same time biochemical progress has outlined how cellular proteostasis networks mediate MP folding and manage misfolding in the cell. When combined with results from genomic sequencing, these studies have established paradigms for how MP folding and misfolding are linked to the molecular etiologies of a variety of diseases. This emerging framework has paved the way for the development of a new class of small molecule "pharmacological chaperones" that bind to and stabilize misfolded MP variants, some of which are now in clinical use. In this review, we comprehensively outline current perspectives on the folding and misfolding of integral MPs as well as the mechanisms of cellular MP quality control. Based on these perspectives, we highlight new opportunities for innovations that bridge our molecular understanding of the energetics of MP folding with the nuanced complexity of biological systems. Given the many linkages between MP misfolding and human disease, we also examine some of the exciting opportunities to leverage these advances to address emerging challenges in the development of therapeutics and precision medicine.
Collapse
Affiliation(s)
- Justin
T. Marinko
- Department
of Biochemistry, Vanderbilt University, Nashville, Tennessee 37240, United States
- Center
for Structural Biology, Vanderbilt University, Nashville, Tennessee 37240, United States
| | - Hui Huang
- Department
of Biochemistry, Vanderbilt University, Nashville, Tennessee 37240, United States
- Center
for Structural Biology, Vanderbilt University, Nashville, Tennessee 37240, United States
| | - Wesley D. Penn
- Department
of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - John A. Capra
- Center
for Structural Biology, Vanderbilt University, Nashville, Tennessee 37240, United States
- Department
of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37245, United States
| | - Jonathan P. Schlebach
- Department
of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Charles R. Sanders
- Department
of Biochemistry, Vanderbilt University, Nashville, Tennessee 37240, United States
| |
Collapse
|
6
|
Noda Y, Arai S, Wada I, Yoda K. Both Svp26 and Mnn6 are required for the efficient ER exit of Mnn4 in Saccharomyces cerevisiae. J GEN APPL MICROBIOL 2019; 65:215-224. [PMID: 30842360 DOI: 10.2323/jgam.2018.10.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Incorporation of membrane and secretory proteins into COPII vesicles are facilitated either by the direct interaction of cargo proteins with COPII coat proteins, or by ER exit adaptor proteins which mediate the interaction of cargo proteins with COPII coat proteins. Svp26 is one of the ER exit adaptor proteins in the yeast Saccharomyces cerevisiae. The ER exit of several type II membrane proteins have been reported to be facilitated by Svp26. We demonstrate here that the efficient incorporation of Mnn4, a type II membrane protein required for mannosyl phosphate transfer to glycoprotein-linked oligosaccharides, into COPII vesicles is also dependent on the function of Svp26. We show that Mnn4 is localized to the Golgi. In addition to Mnn4, Mnn6 is known to be also required for the transfer of mannosyl phosphate to the glycans. We show, by indirect immunofluorescence, that Mnn6 localizes to the ER. As in the case with Svp26, deletion of the MNN6 gene results in the accumulation of Mnn4 in ER. In vitro COPII vesicle budding assays show that Svp26 and Mnn6 facilitate the incorporation of Mnn4 into COPII vesicles. In contrast to Svp26, which is itself efficiently captured into the COPII vesicles, Mnn6 was not incorporated into the COPII vesicles. Mnn4 and Mnn6 have the DXD motif which is often found in the many glycosyltransferases and functions to coordinate a divalent cation essential for the reaction. Alcian blue dye binding assay shows that substitution of the first D in this motif present in Mnn4 by A impairs the Mnn4 function. In contrast, amino acid substitutions in DXD motifs present in Mnn6 did not affect the function of Mnn6. These results suggest that Mnn4 may be directly involved in the mannosyl phosphate transfer reaction.
Collapse
Affiliation(s)
- Yoichi Noda
- Department of Biotechnology, The University of Tokyo.,Collaborative Research Institute for Innovative Microbiology, The University of Tokyo
| | - Seisuke Arai
- Department of Cell Science, Institute of Biomedical Sciences, Fukushima Medical University School of Medicine
| | - Ikuo Wada
- Department of Cell Science, Institute of Biomedical Sciences, Fukushima Medical University School of Medicine
| | - Koji Yoda
- Department of Biotechnology, The University of Tokyo
| |
Collapse
|
7
|
Geva Y, Crissman J, Arakel EC, Gómez-Navarro N, Chuartzman SG, Stahmer KR, Schwappach B, Miller EA, Schuldiner M. Two novel effectors of trafficking and maturation of the yeast plasma membrane H + -ATPase. Traffic 2017; 18:672-682. [PMID: 28727280 PMCID: PMC5607100 DOI: 10.1111/tra.12503] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Revised: 07/17/2017] [Accepted: 07/17/2017] [Indexed: 11/28/2022]
Abstract
The endoplasmic reticulum (ER) is the entry site of proteins into the endomembrane system. Proteins exit the ER via coat protein II (COPII) vesicles in a selective manner, mediated either by direct interaction with the COPII coat or aided by cargo receptors. Despite the fundamental role of such receptors in protein sorting, only a few have been identified. To further define the machinery that packages secretory cargo and targets proteins from the ER to Golgi membranes, we used multiple systematic approaches, which revealed 2 uncharacterized proteins that mediate the trafficking and maturation of Pma1, the essential yeast plasma membrane proton ATPase. Ydl121c (Exp1) is an ER protein that binds Pma1, is packaged into COPII vesicles, and whose deletion causes ER retention of Pma1. Ykl077w (Psg1) physically interacts with Exp1 and can be found in the Golgi and coat protein I (COPI) vesicles but does not directly bind Pma1. Loss of Psg1 causes enhanced degradation of Pma1 in the vacuole. Our findings suggest that Exp1 is a Pma1 cargo receptor and that Psg1 aids Pma1 maturation in the Golgi or affects its retrieval. More generally our work shows the utility of high content screens in the identification of novel trafficking components.
Collapse
Affiliation(s)
- Yosef Geva
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Jonathan Crissman
- Department of Biological Sciences, Columbia University, New York, NY
| | - Eric C Arakel
- Department of Molecular Biology, Universitätsmedizin Göttingen, Göttingen, Germany
| | | | - Silvia G Chuartzman
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Kyle R Stahmer
- Department of Biological Sciences, Columbia University, New York, NY
| | - Blanche Schwappach
- Department of Molecular Biology, Universitätsmedizin Göttingen, Göttingen, Germany
| | - Elizabeth A Miller
- Department of Biological Sciences, Columbia University, New York, NY.,MRC Laboratory of Molecular Biology, Cell Biology Division, Cambridge, UK
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| |
Collapse
|
8
|
Anderson NS, Mukherjee I, Bentivoglio CM, Barlowe C. The Golgin protein Coy1 functions in intra-Golgi retrograde transport and interacts with the COG complex and Golgi SNAREs. Mol Biol Cell 2017; 28:mbc.E17-03-0137. [PMID: 28794270 PMCID: PMC5620376 DOI: 10.1091/mbc.e17-03-0137] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 07/12/2017] [Accepted: 07/31/2017] [Indexed: 01/09/2023] Open
Abstract
Extended coiled-coil proteins of the Golgin family play prominent roles in maintaining the structure and function of the Golgi complex. Here we further investigate the Golgin protein Coy1 and document its function in retrograde transport between early Golgi compartments. Cells that lack Coy1 displayed a reduced half-life of the Och1 mannosyltransferase, an established cargo of intra-Golgi retrograde transport. Combining the coy1Δ mutation with deletions in other putative retrograde Golgins (sgm1Δ and rud3Δ) caused strong glycosylation and growth defects and reduced membrane association of the Conserved Oligomeric Golgi complex. In contrast, overexpression of COY1 inhibited the growth of mutant strains deficient in fusion activity at the Golgi (sed5-1 and sly1-ts). To map Coy1 protein interactions, co-immunoprecipitation experiments revealed an association with the Conserved Oliogmeric Golgi (COG) complex and with intra-Golgi SNARE proteins. These physical interactions are direct, as Coy1 was efficiently captured in vitro by Lobe A of the COG complex and the purified SNARE proteins Gos1, Sed5 and Sft1. Thus, our genetic, in vivo, and biochemical data indicate a role for Coy1 in regulating COG complex-dependent fusion of retrograde-directed COPI vesicles.
Collapse
Affiliation(s)
- Nadine S Anderson
- Department of Biochemistry & Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| | - Indrani Mukherjee
- Department of Biochemistry & Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| | - Christine M Bentivoglio
- Department of Biochemistry & Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| | - Charles Barlowe
- Department of Biochemistry & Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| |
Collapse
|
9
|
Abstract
Transport of newly synthesized proteins from the endoplasmic reticulum (ER) to the Golgi complex is highly selective. As a general rule, such transport is limited to soluble and membrane-associated secretory proteins that have reached properly folded and assembled conformations. To secure the efficiency, fidelity, and control of this crucial transport step, cells use a combination of mechanisms. The mechanisms are based on selective retention of proteins in the ER to prevent uptake into transport vesicles, on selective capture of proteins in COPII carrier vesicles, on inclusion of proteins in these vesicles by default as part of fluid and membrane bulk flow, and on selective retrieval of proteins from post-ER compartments by retrograde vesicle transport.
Collapse
Affiliation(s)
- Charles Barlowe
- Biochemistry Department, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755;
| | - Ari Helenius
- Institute of Biochemistry, ETH Zurich, Zurich CH-8093, Switzerland
| |
Collapse
|
10
|
Carapito C, Lane L, Benama M, Opsomer A, Mouton-Barbosa E, Garrigues L, Gonzalez de Peredo A, Burel A, Bruley C, Gateau A, Bouyssié D, Jaquinod M, Cianferani S, Burlet-Schiltz O, Van Dorsselaer A, Garin J, Vandenbrouck Y. Computational and Mass-Spectrometry-Based Workflow for the Discovery and Validation of Missing Human Proteins: Application to Chromosomes 2 and 14. J Proteome Res 2015; 14:3621-34. [PMID: 26132440 DOI: 10.1021/pr5010345] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
In the framework of the C-HPP, our Franco-Swiss consortium has adopted chromosomes 2 and 14, coding for a total of 382 missing proteins (proteins for which evidence is lacking at protein level). Over the last 4 years, the French proteomics infrastructure has collected high-quality data sets from 40 human samples, including a series of rarely studied cell lines, tissue types, and sample preparations. Here we described a step-by-step strategy based on the use of bioinformatics screening and subsequent mass spectrometry (MS)-based validation to identify what were up to now missing proteins in these data sets. Screening database search results (85,326 dat files) identified 58 of the missing proteins (36 on chromosome 2 and 22 on chromosome 14) by 83 unique peptides following the latest release of neXtProt (2014-09-19). PSMs corresponding to these peptides were thoroughly examined by applying two different MS-based criteria: peptide-level false discovery rate calculation and expert PSM quality assessment. Synthetic peptides were then produced and used to generate reference MS/MS spectra. A spectral similarity score was then calculated for each pair of reference-endogenous spectra and used as a third criterion for missing protein validation. Finally, LC-SRM assays were developed to target proteotypic peptides from four of the missing proteins detected in tissue/cell samples, which were still available and for which sample preparation could be reproduced. These LC-SRM assays unambiguously detected the endogenous unique peptide for three of the proteins. For two of these, identification was confirmed by additional proteotypic peptides. We concluded that of the initial set of 58 proteins detected by the bioinformatics screen, the consecutive MS-based validation criteria led to propose the identification of 13 of these proteins (8 on chromosome 2 and 5 on chromosome 14) that passed at least two of the three MS-based criteria. Thus, a rigorous step-by-step approach combining bioinformatics screening and MS-based validation assays is particularly suitable to obtain protein-level evidence for proteins previously considered as missing. All MS/MS data have been deposited in ProteomeXchange under identifier PXD002131.
Collapse
Affiliation(s)
- Christine Carapito
- Laboratoire de Spectrométrie de Masse BioOrganique (LSMBO), IPHC, Université de Strasbourg, CNRS, UMR7178 , 25 Rue Becquerel, 67087 Strasbourg, France
| | - Lydie Lane
- CALIPHO Group, SIB-Swiss Institute of Bioinformatics, CMU , rue Michel-Servet 1, CH-1211 Geneva 4, Switzerland.,Department of Human Protein Sciences, Faculty of Medicine, rue Michel-Servet 1, CH-1211 Geneva 4, Switzerland
| | - Mohamed Benama
- CEA, DSV, iRTSV, Laboratoire de Biologie à Grande Echelle, 17 rue des martyrs, Grenoble, F-38054, France.,INSERM U1038 , 17, rue des Martyrs, Grenoble F-38054, France.,Université Grenoble , Grenoble F-38054, France
| | - Alisson Opsomer
- Laboratoire de Spectrométrie de Masse BioOrganique (LSMBO), IPHC, Université de Strasbourg, CNRS, UMR7178 , 25 Rue Becquerel, 67087 Strasbourg, France
| | - Emmanuelle Mouton-Barbosa
- CNRS UMR5089 Institut de Pharmacologie et de Biologie Structurale, 118 route de Narbonne, 31077 Toulouse, France.,Université de Toulouse , 205, route de Narbonne, 31077 Toulouse, France
| | - Luc Garrigues
- CNRS UMR5089 Institut de Pharmacologie et de Biologie Structurale, 118 route de Narbonne, 31077 Toulouse, France.,Université de Toulouse , 205, route de Narbonne, 31077 Toulouse, France
| | - Anne Gonzalez de Peredo
- CNRS UMR5089 Institut de Pharmacologie et de Biologie Structurale, 118 route de Narbonne, 31077 Toulouse, France.,Université de Toulouse , 205, route de Narbonne, 31077 Toulouse, France
| | - Alexandre Burel
- Laboratoire de Spectrométrie de Masse BioOrganique (LSMBO), IPHC, Université de Strasbourg, CNRS, UMR7178 , 25 Rue Becquerel, 67087 Strasbourg, France
| | - Christophe Bruley
- CEA, DSV, iRTSV, Laboratoire de Biologie à Grande Echelle, 17 rue des martyrs, Grenoble, F-38054, France.,INSERM U1038 , 17, rue des Martyrs, Grenoble F-38054, France.,Université Grenoble , Grenoble F-38054, France
| | - Alain Gateau
- CALIPHO Group, SIB-Swiss Institute of Bioinformatics, CMU , rue Michel-Servet 1, CH-1211 Geneva 4, Switzerland.,Department of Human Protein Sciences, Faculty of Medicine, rue Michel-Servet 1, CH-1211 Geneva 4, Switzerland
| | - David Bouyssié
- CNRS UMR5089 Institut de Pharmacologie et de Biologie Structurale, 118 route de Narbonne, 31077 Toulouse, France.,Université de Toulouse , 205, route de Narbonne, 31077 Toulouse, France
| | - Michel Jaquinod
- CEA, DSV, iRTSV, Laboratoire de Biologie à Grande Echelle, 17 rue des martyrs, Grenoble, F-38054, France.,INSERM U1038 , 17, rue des Martyrs, Grenoble F-38054, France.,Université Grenoble , Grenoble F-38054, France
| | - Sarah Cianferani
- Laboratoire de Spectrométrie de Masse BioOrganique (LSMBO), IPHC, Université de Strasbourg, CNRS, UMR7178 , 25 Rue Becquerel, 67087 Strasbourg, France
| | - Odile Burlet-Schiltz
- CNRS UMR5089 Institut de Pharmacologie et de Biologie Structurale, 118 route de Narbonne, 31077 Toulouse, France.,Université de Toulouse , 205, route de Narbonne, 31077 Toulouse, France
| | - Alain Van Dorsselaer
- Laboratoire de Spectrométrie de Masse BioOrganique (LSMBO), IPHC, Université de Strasbourg, CNRS, UMR7178 , 25 Rue Becquerel, 67087 Strasbourg, France
| | - Jérôme Garin
- CEA, DSV, iRTSV, Laboratoire de Biologie à Grande Echelle, 17 rue des martyrs, Grenoble, F-38054, France.,INSERM U1038 , 17, rue des Martyrs, Grenoble F-38054, France.,Université Grenoble , Grenoble F-38054, France
| | - Yves Vandenbrouck
- CEA, DSV, iRTSV, Laboratoire de Biologie à Grande Echelle, 17 rue des martyrs, Grenoble, F-38054, France.,INSERM U1038 , 17, rue des Martyrs, Grenoble F-38054, France.,Université Grenoble , Grenoble F-38054, France
| |
Collapse
|
11
|
Rosas-Santiago P, Lagunas-Gómez D, Barkla BJ, Vera-Estrella R, Lalonde S, Jones A, Frommer WB, Zimmermannova O, Sychrová H, Pantoja O. Identification of rice cornichon as a possible cargo receptor for the Golgi-localized sodium transporter OsHKT1;3. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:2733-48. [PMID: 25750424 PMCID: PMC4986874 DOI: 10.1093/jxb/erv069] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Membrane proteins are synthesized and folded in the endoplasmic reticulum (ER), and continue their path to their site of residence along the secretory pathway. The COPII system has been identified as a key player for selecting and directing the fate of membrane and secretory cargo proteins. Selection of cargo proteins within the COPII vesicles is achieved by cargo receptors. The cornichon cargo receptor belongs to a conserved protein family found in eukaryotes that has been demonstrated to participate in the selection of integral membrane proteins as cargo for their correct targeting. Here it is demonstrated at the cellular level that rice cornichon OsCNIH1 interacts with OsHKT1;3 and, in yeast cells, enables the expression of the sodium transporter to the Golgi apparatus. Physical and functional HKT-cornichon interactions are confirmed by the mating-based split ubiquitin system, bimolecular fluorescence complementation, and Xenopus oocyte and yeast expression systems. The interaction between the two proteins occurs in the ER of plant cells and their co-expression in oocytes leads to the sequestration of the transporter in the ER. In the yeast cornichon mutant erv14, OsHKT1;3 is mistargeted, preventing the toxic effects of sodium transport in the cell observed in wild-type cells or in the erv14 mutant that co-expressed OsHKT1;3 with either OsCNIH1 or Erv14p. Identification and characterization of rice cornichon as a possible cargo receptor opens up the opportunity to improve our knowledge on membrane protein targeting in plant cells.
Collapse
Affiliation(s)
- Paul Rosas-Santiago
- Instituto de Biotecnología, Universidad Nacional de Autónoma de México, Cuernavaca, Morelos 62250, México Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305, USA
| | - Daniel Lagunas-Gómez
- Instituto de Biotecnología, Universidad Nacional de Autónoma de México, Cuernavaca, Morelos 62250, México
| | - Bronwyn J Barkla
- Southern Cross Plant Science, Southern Cross University, Lismore, Australia
| | - Rosario Vera-Estrella
- Instituto de Biotecnología, Universidad Nacional de Autónoma de México, Cuernavaca, Morelos 62250, México
| | - Sylvie Lalonde
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305, USA
| | - Alexander Jones
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305, USA
| | - Wolf B Frommer
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305, USA
| | - Olga Zimmermannova
- Southern Cross Plant Science, Southern Cross University, Lismore, Australia
| | - Hana Sychrová
- Department of Membrane Transport, Institute of Physiology, Academy of Sciences of the Czech Republic, v.v.i., 142 20 Prague 4, Czech Republic
| | - Omar Pantoja
- Instituto de Biotecnología, Universidad Nacional de Autónoma de México, Cuernavaca, Morelos 62250, México
| |
Collapse
|
12
|
Abstract
Endoplasmic reticulum (ER) to Golgi trafficking is an essential step in sorting mature, correctly folded, processed and assembled proteins (cargo) from immature proteins and ER-resident proteins. However, the mechanisms governing trafficking selectivity, specificity and regulation are not yet fully understood. To date, three complementary mechanisms have been described that enable regulation of this trafficking step: ER retention of immature proteins in the ER; selective uptake of fully mature proteins into Golgi-bound vesicles; and retrieval from the Golgi of immature cargo that has erroneously exited the ER. Together, these three mechanisms allow incredible specificity and enable the cell to carry out protein quality control and regulate protein processing, oligomerization and expression. This review will focus on the current knowledge of selectivity mechanisms acting during the ER-to-Golgi sorting step and their significance in health and disease. The review will also highlight several key questions that have remained unanswered and discuss the future frontiers.
Collapse
Affiliation(s)
- Yosef Geva
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 761001, Israel
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 761001, Israel.
| |
Collapse
|
13
|
Molecular Mechanisms of the Localization of Membrane Proteins in the Yeast Golgi Compartments. Biosci Biotechnol Biochem 2014; 77:435-45. [DOI: 10.1271/bbb.120982] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
|
14
|
Noda Y, Hara T, Ishii M, Yoda K. Distinct adaptor proteins assist exit of Kre2-family proteins from the yeast ER. Biol Open 2014; 3:209-24. [PMID: 24585773 PMCID: PMC4001239 DOI: 10.1242/bio.20146312] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Svp26 protein of S. cerevisiae is an ER- and Golgi-localized integral membrane protein with 4 potential membrane-spanning domains. It functions as an adaptor protein that facilitates the ER exit of Ktr3, a mannosyltransferase required for biosynthesis of O-linked oligosaccharides, and the ER exit of Mnn2 and Mnn5, mannosyltransferases, which participate in the biosynthesis of N-linked oligosaccharides. Ktr3 belongs to the Kre2 family, which consists of 9 members of type-II membrane proteins sharing sequence similarities. In this report, we examined all Kre2 family members and found that the Golgi localizations of two others, Kre2 and Ktr1, were dependent on Svp26 by immunofluorescence microscopy and cell fractionations in sucrose density gradients. We show that Svp26 functions in facilitating the ER exit of Kre2 and Ktr1 by an in vitro COPII budding assay. Golgi localization of Ktr4 was not dependent on Svp26. Screening null mutants of the genes encoding abundant COPII membrane proteins for those showing mislocalization of Ktr4 in the ER revealed that Erv41 and Erv46 are required for the correct Golgi localization of Ktr4. We provide biochemical evidence that the Erv41-Erv46 complex functions as an adaptor protein for ER exit of Ktr4. This is the first demonstration of the molecular function of this evolutionally conserved protein complex. The domain switching experiments show that the lumenal domain of Ktr4 is responsible for recognition by the Erv41-Erv46 complex. Thus, ER exit of Kre2-family proteins is dependent on distinct adaptor proteins and our results provide new insights into the traffic of Kre2-family mannosyltransferases.
Collapse
Affiliation(s)
- Yoichi Noda
- Department of Biotechnology, University of Tokyo, Yayoi, Bunkyo-Ku, Tokyo 113-8657, Japan
| | | | | | | |
Collapse
|
15
|
Serra-Soriano M, Pallás V, Navarro JA. A model for transport of a viral membrane protein through the early secretory pathway: minimal sequence and endoplasmic reticulum lateral mobility requirements. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2014; 77:863-79. [PMID: 24438546 DOI: 10.1111/tpj.12435] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Revised: 12/30/2013] [Accepted: 01/09/2014] [Indexed: 05/19/2023]
Abstract
Viral movement proteins exploit host endomembranes and the cytoskeleton to move within the cell via routes that, in some cases, are dependent on the secretory pathway. For example, melon necrotic spot virus p7B, a type II transmembrane protein, leaves the endoplasmic reticulum (ER) through the COPII-dependent Golgi pathway to reach the plasmodesmata. Here we investigated the sequence requirements and putative mechanisms governing p7B transport through the early secretory pathway. Deletion of either the cytoplasmic N-terminal region (CR) or the luminal C-terminal region (LR) led to ER retention, suggesting that they are both essential for ER export. Through alanine-scanning mutagenesis, we identified residues in the CR and LR that are critical for both ER export and for viral cell-to-cell movement. Within the CR, alanine substitution of aspartic and proline residues in the DSSP β-turn motif (D7 AP10 A) led to movement of discrete structures along the cortical ER in an actin-dependent manner. In contrast, alanine substitution of a lysine residue in the LR (K49 A) resulted in a homogenous ER distribution of the movement protein and inhibition of ER-Golgi traffic. Moreover, the ability of p7B to recruit Sar1 to the ER membrane is lost in the D7 AP10 A mutant, but enhanced in the K49 A mutant. In addition, fluorescence recovery after photobleaching revealed that K49 A but not D7 AP10 A dramatically diminished protein lateral mobility. From these data, we propose a model whereby the LR directs actin-dependent mobility toward the cortical ER, where the cytoplasmic DSSP β-turn favors assembly of COPII vesicles for export of p7B from the ER.
Collapse
Affiliation(s)
- Marta Serra-Soriano
- Instituto de Biología Molecular y Celular de Plantas, Universitat Politècnica de València/Consejo Superior de Investigaciones Científicas, Avenida Ingeniero Fausto Elio s/n, 46022, Valencia, Spain
| | | | | |
Collapse
|
16
|
Hirata R, Nihei CI, Nakano A. Isoform-selective oligomer formation of Saccharomyces cerevisiae p24 family proteins. J Biol Chem 2013; 288:37057-70. [PMID: 24217251 DOI: 10.1074/jbc.m113.518340] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
p24 family proteins are evolutionarily conserved transmembrane proteins involved in the early secretory pathway. Saccharomyces cerevisiae has 8 known p24 proteins that are classified into four subfamilies (p24α, -β, -γ, and -δ). Emp24 and Erv25 are the sole members of p24β and -δ, respectively, and deletion of either destabilizes the remaining p24 proteins, resulting in p24 null phenotype (p24Δ). We studied genetic and physical interactions of p24α (Erp1, -5, and -6) and γ (Erp2, -3, and -4). Deletion of the major p24α (Erp1) partially inhibited p24 activity as reported previously. A second mutation in either Erp5 or Erp6 aggravated the erp1Δ phenotype, and the triple mutation gave a full p24Δ phenotype. Similar genetic interactions were observed among the major p24γ (Erp2) and the other two γ members. All the p24α/γ isoforms interacted with both p24β and -δ. Interaction between p24β and -δ was isoform-selective, and five major α/γ pairs were detected. These results suggest that the yeast p24 proteins form functionally redundant αβγδ complexes. We also identified Rrt6 as a novel p24δ isoform. Rrt6 shows only limited sequence identity (∼15%) to known p24 proteins but was found to have structural properties characteristic of p24. Rrt6 was induced when cells were grown on glycerol and form an additional αβγδ complex with Erp3, Erp5, and Emp24. This complex was mainly localized to the Golgi, whereas the p24 complex containing Erv25, instead of Rrt6 but otherwise with the same isoform composition, was found mostly in the ER.
Collapse
Affiliation(s)
- Ryogo Hirata
- From the Live Cell Molecular Imaging Research Team, RIKEN Center for Advanced Photonics and
| | | | | |
Collapse
|
17
|
Abstract
The secretory pathway is responsible for the synthesis, folding, and delivery of a diverse array of cellular proteins. Secretory protein synthesis begins in the endoplasmic reticulum (ER), which is charged with the tasks of correctly integrating nascent proteins and ensuring correct post-translational modification and folding. Once ready for forward traffic, proteins are captured into ER-derived transport vesicles that form through the action of the COPII coat. COPII-coated vesicles are delivered to the early Golgi via distinct tethering and fusion machineries. Escaped ER residents and other cycling transport machinery components are returned to the ER via COPI-coated vesicles, which undergo similar tethering and fusion reactions. Ultimately, organelle structure, function, and cell homeostasis are maintained by modulating protein and lipid flux through the early secretory pathway. In the last decade, structural and mechanistic studies have added greatly to the strong foundation of yeast genetics on which this field was built. Here we discuss the key players that mediate secretory protein biogenesis and trafficking, highlighting recent advances that have deepened our understanding of the complexity of this conserved and essential process.
Collapse
|
18
|
D'Arcangelo JG, Stahmer KR, Miller EA. Vesicle-mediated export from the ER: COPII coat function and regulation. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:2464-72. [PMID: 23419775 DOI: 10.1016/j.bbamcr.2013.02.003] [Citation(s) in RCA: 110] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Revised: 02/04/2013] [Accepted: 02/05/2013] [Indexed: 11/26/2022]
Abstract
Vesicle trafficking from the endoplasmic reticulum (ER) is a vital cellular process in all eukaryotes responsible for moving secretory cargoes from the ER to the Golgi apparatus. To accomplish this feat, the cell employs a set of conserved cytoplasmic coat proteins - the coat protein II (COPII) complex - that recruit cargo into nascent buds and deform the ER membrane to drive vesicle formation. While our understanding of COPII coat mechanics has developed substantially since its discovery, we have only recently begun to appreciate the factors that regulate this complex and, in turn, ER-to-Golgi trafficking. Here, we describe these factors and their influences on COPII vesicle formation. Properties intrinsic to the GTP cycle of the coat, as well as coat structure, have critical implications for COPII vesicle trafficking. Extrinsic factors in the cytosol can modulate COPII activity through direct interaction with the coat or with scaffolding components, or by changing composition of the ER membrane. Further, lumenal and membrane-bound cargoes and cargo receptors can influence COPII-mediated trafficking in equally profound ways. Together, these factors work in concert to ensure proper cargo movement in this first step of the secretory pathway. This article is part of a Special Issue entitled: Functional and structural diversity of endoplasmic reticulum.
Collapse
|
19
|
Abstract
The function of the human proteome is defined by the proteostasis network (PN) (Science 2008;319:916; Science 2010;329:766), a biological system that generates, protects, and, where necessary, degrades a protein to optimize the cell, tissue, and organismal response to diet, stress, and aging. Numerous human diseases result from the failure of proteins to fold properly in response to mutation, disrupting the proteome. In the case of the exocytic pathway, this includes proteostasis components that direct folding, and export of proteins from the endoplasmic reticulum (ER). Included here are serpin deficiencies, a class of related diseases that result in a significant reduction of secretion of serine proteinase inhibitors from the liver into serum. In response to misfolding, variants of the serine protease α(1)-antitrypsin (α1AT) fail to exit the ER and are targeted for either ER-associated degradation or autophagic pathways. The challenge for developing α1AT deficiency therapeutics is to understand the PN pathways involved in folding and export. Herein, we review the role of the PN in managing the protein fold and function during synthesis in the ER and trafficking to the cell surface or extracellular space. We highlight the role of the proteostasis boundary to define the operation of the proteome (Annu Rev Biochem 2009;78:959). We discuss how manipulation of folding energetics or the PN by pharmacological intervention could provide multiple routes for restoration of variant α1AT function to the benefit of human health.
Collapse
|
20
|
Abstract
Estimates based on proteomic analyses indicate that a third of translated proteins in eukaryotic genomes enter the secretory pathway. After folding and assembly of nascent secretory proteins in the endoplasmic reticulum (ER), the coat protein complex II (COPII) selects folded cargo for export in membrane-bound vesicles. To accommodate the great diversity in secretory cargo, protein sorting receptors are required in a number of instances for efficient ER export. These transmembrane sorting receptors couple specific secretory cargo to COPII through interactions with both cargo and coat subunits. After incorporation into COPII transport vesicles, protein sorting receptors release bound cargo in pre-Golgi or Golgi compartments, and receptors are then recycled back to the ER for additional rounds of cargo export. Distinct types of protein sorting receptors that recognize carbohydrate and/or polypeptide signals in secretory cargo have been characterized. Our current understanding of the molecular mechanisms underlying cargo receptor function are described.
Collapse
Affiliation(s)
- Julia Dancourt
- Department of Biochemistry, Dartmouth Medical School, Hanover, New Hampshire 03755, USA
| | | |
Collapse
|
21
|
Noda Y, Yoda K. Svp26 facilitates endoplasmic reticulum to golgi transport of a set of mannosyltransferases in Saccharomyces cerevisiae. J Biol Chem 2010; 285:15420-15429. [PMID: 20236934 DOI: 10.1074/jbc.m109.086272] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Svp26 is a polytopic integral membrane protein found in the ER and early Golgi compartment. In the Deltasvp26 cell, the Golgi mannosyltransferase Ktr3 remains in the ER. Here, we report that two other Golgi mannosyltransferases, Mnn2 and Mnn5 are also mislocalized and found in the ER in the absence of Svp26 and that localization of other mannosyltransferases including Mnn1 are not affected. Mnn2 and Mnn5 bind to Svp26 in vivo as Ktr3 does. Using an in vitro budding assay, the incorporation of Ktr3 and Mnn2 in the COPII vesicles is greatly stimulated by the presence of Svp26. As Svp26 itself is an efficient cargo, Svp26 is likely to support selective incorporation of a set of mannosyltransferases into COPII vesicles by working as their adaptor protein. The domain switching between Svp26-dependent Mnn2 or Ktr3 and Svp26-independent Mnn1 suggests that the lumenal domain of mannosyltransferases, but not the cytoplasmic or transmembrane domain, is responsible for recognition by Svp26.
Collapse
Affiliation(s)
- Yoichi Noda
- Department of Biotechnology, University of Tokyo, Yayoi, Bunkyo-Ku, Tokyo 113-8657, Japan
| | - Koji Yoda
- Department of Biotechnology, University of Tokyo, Yayoi, Bunkyo-Ku, Tokyo 113-8657, Japan.
| |
Collapse
|
22
|
Field MC, Sergeenko T, Wang YN, Böhm S, Carrington M. Chaperone requirements for biosynthesis of the trypanosome variant surface glycoprotein. PLoS One 2010; 5:e8468. [PMID: 20052285 PMCID: PMC2797082 DOI: 10.1371/journal.pone.0008468] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2009] [Accepted: 12/03/2009] [Indexed: 11/27/2022] Open
Abstract
Background Trypanosoma brucei does not respond transcriptionally to several endoplasmic reticulum (ER) stress conditions, including tunicamycin or dithiothreitol, indicating the absence of a conventional unfolded protein response. This suggests divergent mechanisms for quality control (QC) of ER protein folding and export may be present in trypanosomes. As the variant surface glycoprotein (VSG) represents ∼90% of trypanosome plasma membrane protein, it is possible that VSG has evolved to fold efficiently to minimize ER folding burden. Methodology/Principal Findings We demonstrate the presence of a QC system by pharmacological inhibition of the trypanosome 26S proteasome. This indicates active proteasome-mediated VSG turnover as ∼2.5 fold more VSG is recovered from cell lysates following MG132 inhibition. An in silico scan of the trypanosome genome identified 28 open reading frames likely to encode polypeptides participating in ER nascent chain maturation. By RNA interference we monitored the importance of these gene products to proliferation, VSG abundance and cell morphology. 68% of the cohort were required for normal proliferation, and depletion of most of these factors resulted in increased VSG abundance, suggesting involvement in ERQC and degradation. Conclusions/Significance The retention of genes for, and the involvement of many gene products in, VSG folding indicates a substantial complexity within the pathways required to perform this role. Counterintuitively, for a super-abundant antigen VSG is apparently made in excess. The biosynthetic excess VSG appears to be turned over efficiently by the proteasome, implying that considerable VSG is rejected by the trypanosome ERQC mechanism. Accordingly, the VSG polypeptide is not well optimized for folding, as only ∼30% attains the native state. Finally as much of the core ERQC system is functionally conserved in trypanosomes, the pathway has an ancient evolutionary origin, and was present in the last common eukaryotic ancestor.
Collapse
Affiliation(s)
- Mark C Field
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom.
| | | | | | | | | |
Collapse
|