1
|
Iswanto ABB, Vu MH, Shon JC, Kumar R, Wu S, Kang H, Kim DR, Son GH, Kim WY, Kwak YS, Liu KH, Kim SH, Kim JY. α1-COP modulates plasmodesmata function through sphingolipid enzyme regulation. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2024. [PMID: 38888228 DOI: 10.1111/jipb.13711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Accepted: 04/30/2024] [Indexed: 06/20/2024]
Abstract
Callose, a β-1,3-glucan plant cell wall polymer, regulates symplasmic channel size at plasmodesmata (PD) and plays a crucial role in a variety of plant processes. However, elucidating the molecular mechanism of PD callose homeostasis is limited. We screened and identified an Arabidopsis mutant plant with excessive callose deposition at PD and found that the mutated gene was α1-COP, a member of the coat protein I (COPI) coatomer complex. We report that loss of function of α1-COP elevates the callose accumulation at PD by affecting subcellular protein localization of callose degradation enzyme PdBG2. This process is linked to the functions of ERH1, an inositol phosphoryl ceramide synthase, and glucosylceramide synthase through physical interactions with the α1-COP protein. Additionally, the loss of function of α1-COP alters the subcellular localization of ERH1 and GCS proteins, resulting in a reduction of GlcCers and GlcHCers molecules, which are key sphingolipid (SL) species for lipid raft formation. Our findings suggest that α1-COP protein, together with SL modifiers controlling lipid raft compositions, regulates the subcellular localization of GPI-anchored PDBG2 proteins, and hence the callose turnover at PD and symplasmic movement of biomolecules. Our findings provide the first key clue to link the COPI-mediated intracellular trafficking pathway to the callose-mediated intercellular signaling pathway through PD.
Collapse
Affiliation(s)
- Arya Bagus Boedi Iswanto
- Division of Applied Life Science (BK21 FOUR Program), Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, 52828, Korea
| | - Minh Huy Vu
- Division of Applied Life Science (BK21 FOUR Program), Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, 52828, Korea
| | - Jong Cheol Shon
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Kyungpook National University, Daegu, 702-701, Korea
| | - Ritesh Kumar
- Division of Applied Life Science (BK21 FOUR Program), Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, 52828, Korea
| | - Shuwei Wu
- Division of Applied Life Science (BK21 FOUR Program), Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, 52828, Korea
| | - Hobin Kang
- Division of Applied Life Science (BK21 FOUR Program), Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, 52828, Korea
| | - Da-Ran Kim
- Departement of Plant Medicine, Gyeongsang National University, Jinju, 52828, Korea
| | - Geon Hui Son
- Division of Applied Life Science (BK21 FOUR Program), Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, 52828, Korea
| | - Woe Yoen Kim
- Division of Applied Life Science (BK21 FOUR Program), Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, 52828, Korea
| | - Youn-Sig Kwak
- Departement of Plant Medicine, Gyeongsang National University, Jinju, 52828, Korea
| | - Kwang Hyeon Liu
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Kyungpook National University, Daegu, 702-701, Korea
| | - Sang Hee Kim
- Division of Applied Life Science (BK21 FOUR Program), Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, 52828, Korea
- Division of Life Science, Gyeongsang National University, Jinju, 52828, Korea
| | - Jae-Yean Kim
- Division of Applied Life Science (BK21 FOUR Program), Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, 52828, Korea
- Division of Life Science, Gyeongsang National University, Jinju, 52828, Korea
| |
Collapse
|
2
|
Dutta T, Chakraborty B, Nigam A, Minocha S, Koner AL. A small-molecule probe to decipher stress-induced ER microenvironments and ER-Golgi communication. J Mater Chem B 2024. [PMID: 38808376 DOI: 10.1039/d4tb00572d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2024]
Abstract
Cellular stress is a crucial factor in regulating and maintaining both organismal and microenvironmental homeostasis. It induces a response that also affects the micropolarity of specific cellular compartments, which is essential for early disease diagnosis. In this contribution, we present a quantitative study of micropolarity changes inside the endoplasmic reticulum (ER) during the G1/S and G2/M phases, using a biocompatible small-molecule fluorophore called ER-Oct. This probe is selectively driven to the ER by its hydrophobicity, and it has the fastest diffusion properties among a series of analogous probes. We found that induced ER stress caused cell cycle arrests leading to an increase in ER micropolarity which is well supported by lambda scanning experiments and fluorescence lifetime imaging microscopy (FLIM) as well. ER-Oct is a versatile staining agent that could effectively stain the ER in various living/fixed mammalian cells, isolated ER, Caenorhabditis elegans, and mice tissues. Furthermore, we used this probe to visualize a well-known biological event, ER to Golgi transport, by live-cell fluorescence microscopy. Our exhaustive investigation of micropolarity using ER-staining dye provides a new way to study ER stress, which could provide a deeper understanding of proteostasis in model systems and even in fixed patient samples.
Collapse
Affiliation(s)
- Tanoy Dutta
- Bionanotechnology Lab, Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal Bypass Road, Bhauri, Bhopal, Madhya Pradesh - 462066, India.
- Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
| | - Barsha Chakraborty
- Bionanotechnology Lab, Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal Bypass Road, Bhauri, Bhopal, Madhya Pradesh - 462066, India.
| | - Aditya Nigam
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, Hauz Khas, New Delhi - 110016, India
| | - Shilpi Minocha
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, Hauz Khas, New Delhi - 110016, India
| | - Apurba Lal Koner
- Bionanotechnology Lab, Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal Bypass Road, Bhauri, Bhopal, Madhya Pradesh - 462066, India.
| |
Collapse
|
3
|
Walton K, Nawara TJ, Angermeier AR, Rosengrant H, Lee E, Wynn B, Victorova E, Belov G, Sztul E. Site-specific phosphorylations of the Arf activator GBF1 differentially regulate GBF1 function in Golgi homeostasis and secretion versus cytokinesis. Sci Rep 2023; 13:13609. [PMID: 37604968 PMCID: PMC10442430 DOI: 10.1038/s41598-023-40705-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Accepted: 08/16/2023] [Indexed: 08/23/2023] Open
Abstract
Diverse cellular processes, including membrane traffic, lipid homeostasis, cytokinesis, mitochondrial positioning, and cell motility are critically dependent on the Sec7 domain guanine nucleotide exchange factor GBF1. Yet, how the participation of GBF1 in a particular cellular function is regulated is unknown. Here, we show that the phosphorylation of specific highly conserved serine and tyrosine residues within the N-terminal domain of GBF1 differentially regulates its function in maintaining Golgi homeostasis and facilitating secretion versus its role in cytokinesis. Specifically, GBF1 mutants containing single amino acid substitutions that mimic a stably phosphorylated S233, S371, Y377, and Y515 or the S233A mutant that can't be phosphorylated are fully able to maintain Golgi architecture and support cargo traffic through the secretory pathway when assessed in multiple functional assays. However, the same mutants cause multi-nucleation when expressed in cells, and appear to inhibit the progression through mitosis and the resolution of cytokinetic bridges. Thus, GBF1 participates in distinct interactive networks when mediating Golgi homeostasis and secretion versus facilitating cytokinesis, and GBF1 integration into such networks is differentially regulated by the phosphorylation of specific GBF1 residues.
Collapse
Affiliation(s)
- Kendall Walton
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, 1918 University Boulevard, MCLM 668, Birmingham, AL, 35233-2008, USA.
| | - Tomasz J Nawara
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, 1918 University Boulevard, MCLM 668, Birmingham, AL, 35233-2008, USA
| | - Allyson R Angermeier
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, 1918 University Boulevard, MCLM 668, Birmingham, AL, 35233-2008, USA
| | - Hadley Rosengrant
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, 1918 University Boulevard, MCLM 668, Birmingham, AL, 35233-2008, USA
| | - Eunjoo Lee
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, 1918 University Boulevard, MCLM 668, Birmingham, AL, 35233-2008, USA
| | - Bridge Wynn
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, 1918 University Boulevard, MCLM 668, Birmingham, AL, 35233-2008, USA
| | - Ekaterina Victorova
- Department of Veterinary Medicine, Virginia-Maryland College of Veterinary Medicine, University of Maryland, College Park, MD, 20742, USA
| | - George Belov
- Department of Veterinary Medicine, Virginia-Maryland College of Veterinary Medicine, University of Maryland, College Park, MD, 20742, USA
| | - Elizabeth Sztul
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, 1918 University Boulevard, MCLM 668, Birmingham, AL, 35233-2008, USA
| |
Collapse
|
4
|
Durmusoglu D, Al'Abri I, Li Z, Islam Williams T, Collins LB, Martínez JL, Crook N. Improving therapeutic protein secretion in the probiotic yeast Saccharomyces boulardii using a multifactorial engineering approach. Microb Cell Fact 2023; 22:109. [PMID: 37287064 PMCID: PMC10245609 DOI: 10.1186/s12934-023-02117-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 05/20/2023] [Indexed: 06/09/2023] Open
Abstract
The probiotic yeast Saccharomyces boulardii (Sb) is a promising chassis to deliver therapeutic proteins to the gut due to Sb's innate therapeutic properties, resistance to phage and antibiotics, and high protein secretion capacity. To maintain therapeutic efficacy in the context of challenges such as washout, low rates of diffusion, weak target binding, and/or high rates of proteolysis, it is desirable to engineer Sb strains with enhanced levels of protein secretion. In this work, we explored genetic modifications in both cis- (i.e. to the expression cassette of the secreted protein) and trans- (i.e. to the Sb genome) that enhance Sb's ability to secrete proteins, taking a Clostridioides difficile Toxin A neutralizing peptide (NPA) as our model therapeutic. First, by modulating the copy number of the NPA expression cassette, we found NPA concentrations in the supernatant could be varied by sixfold (76-458 mg/L) in microbioreactor fermentations. In the context of high NPA copy number, we found a previously-developed collection of native and synthetic secretion signals could further tune NPA secretion between 121 and 463 mg/L. Then, guided by prior knowledge of S. cerevisiae's secretion mechanisms, we generated a library of homozygous single gene deletion strains, the most productive of which achieved 2297 mg/L secretory production of NPA. We then expanded on this library by performing combinatorial gene deletions, supplemented by proteomics experiments. We ultimately constructed a quadruple protease-deficient Sb strain that produces 5045 mg/L secretory NPA, an improvement of > tenfold over wild-type Sb. Overall, this work systematically explores a broad collection of engineering strategies to improve protein secretion in Sb and highlights the ability of proteomics to highlight under-explored mediators of this process. In doing so, we created a set of probiotic strains that are capable of delivering a wide range of protein titers and therefore furthers the ability of Sb to deliver therapeutics to the gut and other settings to which it is adapted.
Collapse
Affiliation(s)
- Deniz Durmusoglu
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC, USA
| | - Ibrahim Al'Abri
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC, USA
| | - Zidan Li
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC, USA
| | - Taufika Islam Williams
- Molecular Education, Technology and Research Innovation Center (METRIC), North Carolina State University, Raleigh, NC, USA
- Department of Chemistry, North Carolina State University, Raleigh, NC, USA
| | - Leonard B Collins
- Molecular Education, Technology and Research Innovation Center (METRIC), North Carolina State University, Raleigh, NC, USA
| | - José L Martínez
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Nathan Crook
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC, USA.
| |
Collapse
|
5
|
Wang H, Pang AP, Wang W, Li B, Li C, Wu FG, Lin F. Discovery of ER-localized sugar transporters for cellulase production with lac1 being essential. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2022; 15:132. [PMID: 36443855 PMCID: PMC9706901 DOI: 10.1186/s13068-022-02230-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Accepted: 11/12/2022] [Indexed: 11/30/2022]
Abstract
BACKGROUND In the process of cellulose hydrolysis, carbohydrate hydrolysates are transported into cells through membrane transporters, and then affect the expression of cellulase-encoding genes. Sugar transporters play a crucial role in cellulase production in lignocellulolytic fungi, of which relatively few have been functionally validated to date and are all reported to be on cell membrane. RESULT Through transcriptome analysis and qRT-PCR, three putative MFS sugar transporters GST, MFS, and LAC1 were found to display significantly higher mRNA levels in T. reesei grown on cellulose than on glucose. The individual deletion of these three genes compromised cellulase production and delayed sugar absorption by 24 h in T. reesei. Nevertheless, they transported pretty low level of sugars, including galactose, lactose, and mannose, and did not transport glucose, when expressed in yeast system. Meanwhile, all three transporters were unexpectedly found to be intracellular, being located in endoplasmic reticulum (ER). Particularly, the knockout of lac1 almost abolished cellulase production, and significantly inhibited biomass generation regardless of sugar types, indicating that lac1 is essential for cellulase production and biomass formation. The absence of lac1 upregulated genes involved in ribosome biogenesis, while downregulated genes in cellulase production, protein processing in ER (particularly protein glycosylation), and lipid biosynthesis. The inhibition of lac1 deletion on the transcriptional levels of genes related to cellulase biosynthesis was restored after 72 h, but the cellulase production was still inhibited, indicating lac1 might pose a post-transcription regulation on cellulase production that are independent on the known cellulase regulation mediated by CRT1 and XYR1. CONCLUSION For the first time, intracellular sugar transporters (mfs, gst, and lac1) facilitating cellulase production were identified, which was distributed in ER. Their sugar transporting ability was very weak, indicating that they might be related to sugar utilization inside cells rather than the cellular sugar uptake. More importantly, sugar transporter lac1 is first found to be essential for cellulase production and biomass formation by affecting protein processing in ER (particularly protein glycosylation) and lipid biosynthesis. The effect of LAC1 on cellulase production seems to be post-transcriptional at late stage of cellulase production, independent on the well-known cellulase regulation mediated by CRT1 and XYR1. These findings improve the understanding of intracellular sugar transporters in fungi and their important role in cellulase synthesis.
Collapse
Affiliation(s)
- Haiyan Wang
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing, China
| | - Ai-Ping Pang
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing, China
| | - Wei Wang
- State Key Lab of Bioreactor Engineering, New World Institute of Biotechnology, East China University of Science and Technology, Shanghai, China
| | - Bingzhi Li
- Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin, China
| | - Chengcheng Li
- School of Light Ind. & Food Sci. and Joint International Research Lab of Lignocellulosic Functional Materials, Nanjing Forestry University, Nanjing, 210037, China
| | - Fu-Gen Wu
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing, China
| | - Fengming Lin
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing, China.
| |
Collapse
|
6
|
Malis Y, Hirschberg K, Kaether C. Hanging the coat on a collar: Same function but different localization and mechanism for COPII. Bioessays 2022; 44:e2200064. [DOI: 10.1002/bies.202200064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 07/25/2022] [Accepted: 07/26/2022] [Indexed: 11/09/2022]
Affiliation(s)
- Yehonathan Malis
- Department of Pathology, Sackler School of Medicine Tel‐Aviv University Tel Aviv Israel
| | - Koret Hirschberg
- Department of Pathology, Sackler School of Medicine Tel‐Aviv University Tel Aviv Israel
| | - Christoph Kaether
- Leibniz Institute for Age Research – Fritz Lipmann Institute Jena Germany
| |
Collapse
|
7
|
Casler JC, Johnson N, Krahn AH, Pantazopoulou A, Day KJ, Glick BS. Clathrin adaptors mediate two sequential pathways of intra-Golgi recycling. J Cell Biol 2022; 221:212747. [PMID: 34739034 PMCID: PMC8576872 DOI: 10.1083/jcb.202103199] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 09/16/2021] [Accepted: 10/26/2021] [Indexed: 01/11/2023] Open
Abstract
The pathways of membrane traffic within the Golgi apparatus are not fully known. This question was addressed using the yeast Saccharomyces cerevisiae, in which the maturation of individual Golgi cisternae can be visualized. We recently proposed that the AP-1 clathrin adaptor mediates intra-Golgi recycling late in the process of cisternal maturation. Here, we demonstrate that AP-1 cooperates with the Ent5 clathrin adaptor to recycle a set of Golgi transmembrane proteins, including some that were previously thought to pass through endosomes. This recycling can be detected by removing AP-1 and Ent5, thereby diverting the AP-1/Ent5-dependent Golgi proteins into an alternative recycling loop that involves traffic to the plasma membrane followed by endocytosis. Unexpectedly, various AP-1/Ent5-dependent Golgi proteins show either intermediate or late kinetics of residence in maturing cisternae. We infer that the AP-1/Ent5 pair mediates two sequential intra-Golgi recycling pathways that define two classes of Golgi proteins. This insight can explain the polarized distribution of transmembrane proteins in the Golgi.
Collapse
Affiliation(s)
- Jason C Casler
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL
| | - Natalie Johnson
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL
| | - Adam H Krahn
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL
| | - Areti Pantazopoulou
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL
| | - Kasey J Day
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL
| | - Benjamin S Glick
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL
| |
Collapse
|
8
|
Khakurel A, Kudlyk T, Bonifacino JS, Lupashin VV. The Golgi-associated retrograde protein (GARP) complex plays an essential role in the maintenance of the Golgi glycosylation machinery. Mol Biol Cell 2021; 32:1594-1610. [PMID: 34161137 PMCID: PMC8351751 DOI: 10.1091/mbc.e21-04-0169] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 05/24/2021] [Accepted: 06/14/2021] [Indexed: 11/18/2022] Open
Abstract
The Golgi complex is a central hub for intracellular protein trafficking and glycosylation. Steady-state localization of glycosylation enzymes is achieved by a combination of mechanisms involving retention and recycling, but the machinery governing these mechanisms is poorly understood. Herein we show that the Golgi-associated retrograde protein (GARP) complex is a critical component of this machinery. Using multiple human cell lines, we show that depletion of GARP subunits impairs Golgi modification of N- and O-glycans and reduces the stability of glycoproteins and Golgi enzymes. Moreover, GARP-knockout (KO) cells exhibit reduced retention of glycosylation enzymes in the Golgi. A RUSH assay shows that, in GARP-KO cells, the enzyme beta-1,4-galactosyltransferase 1 is not retained at the Golgi complex but instead is missorted to the endolysosomal system. We propose that the endosomal system is part of the trafficking itinerary of Golgi enzymes or their recycling adaptors and that the GARP complex is essential for recycling and stabilization of the Golgi glycosylation machinery. [Media: see text].
Collapse
Affiliation(s)
- Amrita Khakurel
- University of Arkansas for Medical Sciences, Department of Physiology and Cell Biology, Little Rock, AR 72205
| | - Tetyana Kudlyk
- University of Arkansas for Medical Sciences, Department of Physiology and Cell Biology, Little Rock, AR 72205
| | - Juan S. Bonifacino
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892
| | - Vladimir V. Lupashin
- University of Arkansas for Medical Sciences, Department of Physiology and Cell Biology, Little Rock, AR 72205
| |
Collapse
|
9
|
Aspergillus fumigatus Cyp51A and Cyp51B Proteins Are Compensatory in Function and Localize Differentially in Response to Antifungals and Cell Wall Inhibitors. Antimicrob Agents Chemother 2020; 64:AAC.00735-20. [PMID: 32660997 DOI: 10.1128/aac.00735-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 07/06/2020] [Indexed: 02/02/2023] Open
Abstract
Triazole antifungals are the primary therapeutic option against invasive aspergillosis. However, resistance to azoles has increased dramatically over the last decade. Azole resistance is known to primarily occur due to point mutations in the azole target protein Cyp51A, one of two paralogous 14-α sterol demethylases found in Aspergillus fumigatus Despite the importance of Cyp51A, little is known about the function of its paralog, Cyp51B, and the behavior of these proteins within the cell or their functional interrelationship. In this study, we addressed two important aspects of the Cyp51 proteins: (i) we characterized their localization patterns under normal growth versus stress conditions, and (ii) we determined how the proteins compensate for each other's absence and respond to azole treatment. Both the Cyp51A and Cyp51B proteins were found to localize in distinct endoplasmic reticulum (ER) domains, including the perinuclear ER and the peripheral ER. Occasionally, the Cyp51 proteins concentrated in the peripheral ER network of tubules along the hyphal septa and at the hyphal tips. Exposure to voriconazole, caspofungin, and Congo red led to significant increases in fluorescence intensity in these alternative localization sites, indicative of Cyp51 protein translocation in response to cell wall stress. Furthermore, deletion of either Cyp51 paralog increased susceptibility to voriconazole, though a greater effect was observed following deletion of cyp51A, indicating a compensatory response to stress conditions.
Collapse
|
10
|
Abstract
Intracellular trafficking and localization studies of spike protein from SARS and OC43 showed that SARS spike protein is localized in the ER or ERGIC compartment and OC43 spike protein is predominantly localized in the lysosome. Differential localization can be explained by signal sequence. The sequence alignment using Clustal W shows that the signal sequence present at the cytoplasmic tail plays an important role in spike protein localization. A unique GYQEL motif is identified at the cytoplasmic terminal of OC43 spike protein which helps in localization in the lysosome, and a novel KLHYT motif is identified in the cytoplasmic tail of SARS spike protein which helps in ER or ERGIC localization. This study sheds some light on the role of cytoplasmic tail of spike protein in cell-to-cell fusion, coronavirus host cell fusion and subsequent pathogenicity.
Collapse
|
11
|
Cox NJ, Luo PM, Smith TJ, Bisnett BJ, Soderblom EJ, Boyce M. A Novel Glycoproteomics Workflow Reveals Dynamic O-GlcNAcylation of COPγ1 as a Candidate Regulator of Protein Trafficking. Front Endocrinol (Lausanne) 2018; 9:606. [PMID: 30459710 PMCID: PMC6232944 DOI: 10.3389/fendo.2018.00606] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 09/24/2018] [Indexed: 02/04/2023] Open
Abstract
O-linked β-N-acetylglucosamine (O-GlcNAc) is an abundant and essential intracellular form of protein glycosylation in animals and plants. In humans, dysregulation of O-GlcNAcylation occurs in a wide range of diseases, including cancer, diabetes, and neurodegeneration. Since its discovery more than 30 years ago, great strides have been made in understanding central aspects of O-GlcNAc signaling, including identifying thousands of its substrates and characterizing the enzymes that govern it. However, while many O-GlcNAcylated proteins have been reported, only a small subset of these change their glycosylation status in response to a typical stimulus or stress. Identifying the functionally important O-GlcNAcylation changes in any given signaling context remains a significant challenge in the field. To address this need, we leveraged chemical biology and quantitative mass spectrometry methods to create a new glycoproteomics workflow for profiling stimulus-dependent changes in O-GlcNAcylated proteins. In proof-of-principle experiments, we used this new workflow to interrogate changes in O-GlcNAc substrates in mammalian protein trafficking pathways. Interestingly, our results revealed dynamic O-GlcNAcylation of COPγ1, an essential component of the coat protein I (COPI) complex that mediates Golgi protein trafficking. Moreover, we detected 11 O-GlcNAc moieties on COPγ1 and found that this modification is reduced by a model secretory stress that halts COPI trafficking. Our results suggest that O-GlcNAcylation may regulate the mammalian COPI system, analogous to its previously reported roles in other protein trafficking pathways. More broadly, our glycoproteomics workflow is applicable to myriad systems and stimuli, empowering future studies of O-GlcNAc in a host of biological contexts.
Collapse
Affiliation(s)
- Nathan J. Cox
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, United States
| | - Peter M. Luo
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, United States
| | - Timothy J. Smith
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, United States
| | - Brittany J. Bisnett
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, United States
| | - Erik J. Soderblom
- Proteomics and Metabolomics Core Facility, Center for Genomic and Computational Biology, Duke University, Durham, NC, United States
| | - Michael Boyce
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, United States
- *Correspondence: Michael Boyce
| |
Collapse
|
12
|
Genome-Wide Screen Reveals sec21 Mutants of Saccharomyces cerevisiae Are Methotrexate-Resistant. G3-GENES GENOMES GENETICS 2017; 7:1251-1257. [PMID: 28235825 PMCID: PMC5386873 DOI: 10.1534/g3.116.038117] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Drug resistance is a consequence of how most modern medicines work. Drugs exert pressure on cells that causes death or the evolution of resistance. Indeed, highly specific drugs are rendered ineffective by a single DNA mutation. In this study, we apply the drug methotrexate, which is widely used in cancer and rheumatoid arthritis, and perform evolution experiments on Baker's yeast to ask the different ways in which cells become drug resistant. Because of the conserved nature of biological pathways between yeast and man, our results can inform how the same mechanism may operate to render human cells resistant to treatment. Exposure of cells to small molecules and drug therapies imposes a strong selective pressure. As a result, cells rapidly acquire mutations in order to survive. These include resistant variants of the drug target as well as those that modulate drug transport and detoxification. To systematically explore how cells acquire drug resistance in an unbiased manner, rapid cost-effective approaches are required. Methotrexate, as one of the first rationally designed anticancer drugs, has served as a prototypic example of such acquired resistance. Known methotrexate resistance mechanisms include mutations that increase expression of the dihydrofolate reductase (DHFR) target as well as those that maintain function yet reduce the drug's binding affinity. Recent evidence suggests that target-independent, epistatic mutations can also result in resistance to methotrexate. Currently, however, the relative contribution of such unlinked resistance mutations is not well understood. To address this issue, we took advantage of Saccharomyces cerevisiae as a model eukaryotic system that combined with whole-genome sequencing and a rapid screening methodology, allowed the identification of causative mutations that modulate resistance to methotrexate. We found a recurrent missense mutation in SEC21 (orthologous to human COPG1), which we confirmed in 10 de novo methotrexate-resistant strains. This sec21 allele (S96L) behaves as a recessive, gain-of-function allele, conferring methotrexate resistance that is abrogated by the presence of a wild-type copy of SEC21 These observations indicate that the Sec21p/COPI transport complex has previously uncharacterized roles in modulating methotrexate stress.
Collapse
|
13
|
Bean BDM, Davey M, Conibear E. Cargo selectivity of yeast sorting nexins. Traffic 2017; 18:110-122. [PMID: 27883263 DOI: 10.1111/tra.12459] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Revised: 11/21/2016] [Accepted: 11/21/2016] [Indexed: 01/09/2023]
Abstract
Sorting nexins are PX domain-containing proteins that bind phospholipids and often act in membrane trafficking where they help to select cargo. However, the functions and cargo specificities of many sorting nexins are unknown. Here, a high-throughput imaging screen was used to identify new sorting nexin cargo in the yeast Saccharomyces cerevisiae. Deletions of 9 different sorting nexins were screened for mislocalization of a set of green fluorescent protein (GFP)-tagged membrane proteins found at the plasma membrane, Golgi or endosomes. This identified 27 proteins that require 1 or more sorting nexins for their correct localization, 23 of which represent novel sorting nexin cargo. Nine hits whose sorting was dependent on Snx4, the sorting nexin-containing retromer complex, or both retromer and Snx3, were examined in detail to search for potential sorting motifs. We identified cytosolic domains of Ear1, Ymd8 and Ymr010w that conferred retromer-dependent sorting on a chimeric reporter and identified conserved residues required for this sorting in a functional assay. This work defined a consensus sequence for retromer and Snx3-dependent sorting.
Collapse
Affiliation(s)
- Björn D M Bean
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, University of British Columbia, Vancouver, Canada
| | - Michael Davey
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, University of British Columbia, Vancouver, Canada
| | - Elizabeth Conibear
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, University of British Columbia, Vancouver, Canada
| |
Collapse
|
14
|
Dysfunction of Wntless triggers the retrograde Golgi-to-ER transport of Wingless and induces ER stress. Sci Rep 2016; 6:19418. [PMID: 26887613 PMCID: PMC4757895 DOI: 10.1038/srep19418] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Accepted: 12/14/2015] [Indexed: 01/02/2023] Open
Abstract
Secreted Wnts play diverse roles in a non-cell-autonomous fashion. However, the cell-autonomous effect of unsecreted Wnts remains unknown. Endoplasmic reticulum (ER) stress is observed in specialized secretory cells and participates in pathophysiological processes. The correlation between Wnt secretion and ER stress remains poorly understood. Here, we demonstrated that Drosophila miR-307a initiates ER stress specifically in wingless (wg)-expressing cells through targeting wntless (wls/evi). This phenotype could be mimicked by retromer loss-of-function or porcupine (porc) depletion, and rescued by wg knockdown, arguing that unsecreted Wg triggers ER stress. Consistently, we found that disrupting the secretion of human Wnt5a also induced ER stress in mammalian cells. Furthermore, we showed that a C-terminal KKVY-motif of Wg is required for its retrograde Golgi-to-ER transport, thus inducing ER stress. Next, we investigated if COPI, the regulator of retrograde transport, is responsible for unsecreted Wg to induce ER stress. To our surprise, we found that COPI acts as a novel regulator of Wg secretion. Taken together, this study reveals a previously unknown Golgi-to-ER retrograde route of Wg, and elucidates a correlation between Wnt secretion and ER stress during development.
Collapse
|
15
|
Papanikou E, Day KJ, Austin J, Glick BS. COPI selectively drives maturation of the early Golgi. eLife 2015; 4. [PMID: 26709839 PMCID: PMC4758959 DOI: 10.7554/elife.13232] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Accepted: 12/27/2015] [Indexed: 12/12/2022] Open
Abstract
COPI coated vesicles carry material between Golgi compartments, but the role of COPI in the secretory pathway has been ambiguous. Previous studies of thermosensitive yeast COPI mutants yielded the surprising conclusion that COPI was dispensable both for the secretion of certain proteins and for Golgi cisternal maturation. To revisit these issues, we optimized the anchor-away method, which allows peripheral membrane proteins such as COPI to be sequestered rapidly by adding rapamycin. Video fluorescence microscopy revealed that COPI inactivation causes an early Golgi protein to remain in place while late Golgi proteins undergo cycles of arrival and departure. These dynamics generate partially functional hybrid Golgi structures that contain both early and late Golgi proteins, explaining how secretion can persist when COPI has been inactivated. Our findings suggest that cisternal maturation involves a COPI-dependent pathway that recycles early Golgi proteins, followed by multiple COPI-independent pathways that recycle late Golgi proteins. DOI:http://dx.doi.org/10.7554/eLife.13232.001 Proteins play many important roles for cells, and these roles often require the proteins to be in particular locations in or around the cells. A set of cell compartments called the Golgi packages certain proteins into bubble-like structures called vesicles to enable the proteins to be used elsewhere in the cell or released to the outside of the cell, in a process called the secretory pathway. The operation of the secretory pathway requires the Golgi compartments to be continually remodeled. Proteins and other materials can be ferried between the compartments of the Golgi by another type of vesicle. These vesicles are coated with a group, or complex, of proteins called COPI, which forms a curved lattice around the vesicles and helps them to capture the materials they will transport. However, it is not clear whether COPI is also involved in remodeling of the Golgi compartments. Papanikou, Day et al. addressed this question using a technique called the “anchor-away method” combined with microscopy to study COPI in yeast cells. The yeast were genetically engineered so that COPI activity was effectively shut down in the presence of a drug called rapamycin. The experiments show that COPI is involved in the early stages of remodeling the Golgi compartments, but not the later stages. This finding supports the emerging view of the Golgi as a self-organizing cellular machine, and it provides a framework for uncovering the engineering principles that underlie the secretory pathway. DOI:http://dx.doi.org/10.7554/eLife.13232.002
Collapse
Affiliation(s)
- Effrosyni Papanikou
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, United States
| | - Kasey J Day
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, United States
| | - Jotham Austin
- Electron Microscopy Core Facility, The University of Chicago, Chicago, United States
| | - Benjamin S Glick
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, United States
| |
Collapse
|
16
|
Tan J, Brill JA. Cinderella story: PI4P goes from precursor to key signaling molecule. Crit Rev Biochem Mol Biol 2013; 49:33-58. [PMID: 24219382 DOI: 10.3109/10409238.2013.853024] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Phosphatidylinositol lipids are signaling molecules involved in nearly all aspects of cellular regulation. Production of phosphatidylinositol 4-phosphate (PI4P) has long been recognized as one of the first steps in generating poly-phosphatidylinositol phosphates involved in actin organization, cell migration, and signal transduction. In addition, progress over the last decade has brought to light independent roles for PI4P in membrane trafficking and lipid homeostasis. Here, we describe recent advances that reveal the breadth of processes regulated by PI4P, the spectrum of PI4P effectors, and the mechanisms of spatiotemporal control that coordinate crosstalk between PI4P and cellular signaling pathways.
Collapse
Affiliation(s)
- Julie Tan
- Department of Molecular Genetics, University of Toronto , Toronto, Ontario , Canada and
| | | |
Collapse
|
17
|
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.
Collapse
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
| | | | | | | | | | | |
Collapse
|
18
|
Claerhout S, Dutta B, Bossuyt W, Zhang F, Nguyen-Charles C, Dennison JB, Yu Q, Yu S, Balázsi G, Lu Y, Mills GB. Abortive autophagy induces endoplasmic reticulum stress and cell death in cancer cells. PLoS One 2012; 7:e39400. [PMID: 22745748 PMCID: PMC3383753 DOI: 10.1371/journal.pone.0039400] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2011] [Accepted: 05/21/2012] [Indexed: 11/19/2022] Open
Abstract
Autophagic cell death or abortive autophagy has been proposed to eliminate damaged as well as cancer cells, but there remains a critical gap in our knowledge in how this process is regulated. The goal of this study was to identify modulators of the autophagic cell death pathway and elucidate their effects on cellular signaling and function. The result of our siRNA library screenings show that an intact coatomer complex I (COPI) is obligatory for productive autophagy. Depletion of COPI complex members decreased cell survival and impaired productive autophagy which preceded endoplasmic reticulum stress. Further, abortive autophagy provoked by COPI depletion significantly altered growth factor signaling in multiple cancer cell lines. Finally, we show that COPI complex members are overexpressed in an array of cancer cell lines and several types of cancer tissues as compared to normal cell lines or tissues. In cancer tissues, overexpression of COPI members is associated with poor prognosis. Our results demonstrate that the coatomer complex is essential for productive autophagy and cellular survival, and thus inhibition of COPI members may promote cell death of cancer cells when apoptosis is compromised.
Collapse
Affiliation(s)
- Sofie Claerhout
- Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas, United States of America.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Jeong K, Kwon H, Lee J, Jang D, Hwang EM, Park JY, Pak Y. Rab6-mediated retrograde transport regulates inner nuclear membrane targeting of caveolin-2 in response to insulin. Traffic 2012; 13:1218-33. [PMID: 22607032 DOI: 10.1111/j.1600-0854.2012.01378.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2011] [Revised: 05/14/2012] [Accepted: 05/18/2012] [Indexed: 01/05/2023]
Abstract
Here, we have identified a retrograde transport pathway of caveolin-2 (cav-2) for its regulatory function in the nucleus. Confocal microscopy analysis, photoactivation experiments and subcellular fractionation revealed that cav-2 localized in the Golgi was transported to the inner nuclear membrane (INM) in response to insulin. Exogenous caveolin-1 (cav-1) and P132L-cav-1 expression did not affect the Golgi localization and insulin-induced INM targeting of cav-2. Cav-2(DKV) mutant in the endoplasmic reticulum (ER) was unable to translocate to the INM in response to insulin. The GTP-bound form of Rab6 promoted, but Rab6 siRNA and the GDP-bound form of Rab6 abrogated, retrograde trafficking of cav-2 from the Golgi to ER. Colchicine or nocodazole treatment abolished insulin-induced INM targeting of cav-2. Knock down of gp210 inhibited insulin-induced import of cav-2 from ER/outer nuclear membrane (ONM) to the INM. The INM-targeted cav-2 prevented heterochromatinization and promoted transcriptional activation of Elk-1 and signal transducer and activator of transcription 3 (STAT3). The results provide molecular mechanisms for insulin-induced INM translocation of cav-2 initiated (i) by Golgi-to-ER retrograde trafficking of cav-2 via microtubule-based Rab6-GTP-dependent transport and subsequently processed (ii) by gp210-mediated import of cav-2 from ER/ONM to INM.
Collapse
Affiliation(s)
- Kyuho Jeong
- Department of Biochemistry, Division of Applied Life Science (BK21 Program), PMBBRC, Gyeongsang National University, Jinju 660-701, Korea
| | | | | | | | | | | | | |
Collapse
|
20
|
Zwiewka M, Friml J. Fluorescence imaging-based forward genetic screens to identify trafficking regulators in plants. FRONTIERS IN PLANT SCIENCE 2012; 3:97. [PMID: 22654887 PMCID: PMC3359526 DOI: 10.3389/fpls.2012.00097] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2012] [Accepted: 04/25/2012] [Indexed: 05/25/2023]
Abstract
Coordinated, subcellular trafficking of proteins is one of the fundamental properties of the multicellular eukaryotic organisms. Trafficking involves a large diversity of compartments, pathways, cargo molecules, and vesicle-sorting events. It is also crucial in regulating the localization and, thus, the activity of various proteins, but the process is still poorly genetically defined in plants. In the past, forward genetics screens had been used to determine the function of genes by searching for a specific morphological phenotype in the organism population in which mutations had been induced chemically or by irradiation. Unfortunately, these straightforward genetic screens turned out to be limited in identifying new regulators of intracellular protein transport, because mutations affecting essential trafficking pathways often lead to lethality. In addition, the use of these approaches has been restricted by functional redundancy among trafficking regulators. Screens for mutants that rely on the observation of changes in the cellular localization or dynamics of fluorescent subcellular markers enable, at least partially, to circumvent these issues. Hence, such image-based screens provide the possibility to identify either alleles with weak effects or components of the subcellular trafficking machinery that have no strong impact on the plant growth.
Collapse
Affiliation(s)
- Marta Zwiewka
- Department of Plant Systems Biology, VIB Life Sciences Research InstituteGent, Belgium
- Department of Plant Biotechnology and Genetics, Ghent UniversityGent, Belgium
| | - Jiří Friml
- Department of Plant Systems Biology, VIB Life Sciences Research InstituteGent, Belgium
- Department of Plant Biotechnology and Genetics, Ghent UniversityGent, Belgium
| |
Collapse
|
21
|
Abstract
A variety of secretory cargoes move through the Golgi, but the pathways and mechanisms of this traffic are still being debated. Here, we evaluate the strengths and weaknesses of five current models for Golgi traffic: (1) anterograde vesicular transport between stable compartments, (2) cisternal progression/maturation, (3) cisternal progression/maturation with heterotypic tubular transport, (4) rapid partitioning in a mixed Golgi, and (5) stable compartments as cisternal progenitors. Each model is assessed for its ability to explain a set of key observations encompassing multiple cell types. No single model can easily explain all of the observations from diverse organisms. However, we propose that cisternal progression/maturation is the best candidate for a conserved core mechanism of Golgi traffic, and that some cells elaborate this core mechanism by means of heterotypic tubular transport between cisternae.
Collapse
Affiliation(s)
- Benjamin S Glick
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, Illinois 60637, USA.
| | | |
Collapse
|
22
|
Langhans M, Förster S, Helmchen G, Robinson DG. Differential effects of the brefeldin A analogue (6R)-hydroxy-BFA in tobacco and Arabidopsis. JOURNAL OF EXPERIMENTAL BOTANY 2011; 62:2949-57. [PMID: 21357769 DOI: 10.1093/jxb/err007] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The effects of two brefeldin A (BFA) analogues (BFA lactam; 6(R)-hydroxy-BFA) on plant cells were tested. Although these two compounds elicited BFA-like effects in mammalian cells, the lactam analogue failed to elicit a response in plant cells. By contrast, while the 6(R)-hydroxy-BFA analogue gave rise to a classic BFA response in tobacco mesophyll protoplasts and true leaves of Arabidopsis (redistribution of Golgi enzymes into the ER), it failed to cause the formation of BFA-compartments in Arabidopsis root cells and cotyledonary leaves. Even when the GNL1-LM mutant of Arabidopsis, which has a cis-Golgi located BFA-sensitive ARF-GEF, was used, the 6(R)-hydroxy analogue failed to elicit a response at conventional BFA concentrations. Only at concentrations of over 200 μM did 6(R)-hydroxy-BFA elicit a BFA-like effect. These differences are interpreted in terms of the different properties of the respective TGN- (Arabidopsis roots) and cis-Golgi- (tobacco mesophyll) localized BFA-sensitive ARF-GEFs.
Collapse
Affiliation(s)
- Markus Langhans
- Department of Cell Biology, Heidelberg Institute for Plant Sciences, University of Heidelberg, D-69120 Heidelberg, Germany
| | | | | | | |
Collapse
|
23
|
Sahlmüller MC, Strating JRPM, Beck R, Eckert P, Popoff V, Haag M, Hellwig A, Berger I, Brügger B, Wieland FT. Recombinant Heptameric Coatomer Complexes: Novel Tools to Study Isoform-Specific Functions. Traffic 2011; 12:682-92. [DOI: 10.1111/j.1600-0854.2011.01177.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
|
24
|
Migration-associated secretion of melanoma inhibitory activity at the cell rear is supported by KCa3.1 potassium channels. Cell Res 2010; 20:1224-38. [DOI: 10.1038/cr.2010.121] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
|
25
|
Crystal structure of alpha-COP in complex with epsilon-COP provides insight into the architecture of the COPI vesicular coat. Proc Natl Acad Sci U S A 2010; 107:11271-6. [PMID: 20534429 DOI: 10.1073/pnas.1006297107] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The heptameric coatomer complex forms the protein shell of membrane-bound vesicles that are involved in transport from the Golgi to the endoplasmatic reticulum and in intraGolgi trafficking. The heptamer can be dissected into a heterotetrameric F-subcomplex, which displays similarities to the adapter complex of the "inner" coat in clathrin-coated vesicles, and a heterotrimeric B-subcomplex, which is believed to form an "outer" coat with a morphology distinct from that of clathrin-coated vesicles. We have determined the crystal structure of the complex between the C-terminal domain (CTD) of alpha-COP and full-length epsilon-COP, two components of the B-subcomplex, at a 2.9 A resolution. The alpha-COP(CTD) x epsilon-COP heterodimer forms a rod-shaped structure, in which epsilon-COP adopts a tetratricopeptide repeat (TPR) fold that deviates substantially from the canonical superhelical conformation. The alpha-COP CTD adopts a U-shaped architecture that complements the TPR fold of epsilon-COP. The epsilon-COP TPRs form a circular bracelet that wraps around a protruding beta-hairpin of the alpha-COP CTD, thus interlocking the two proteins. The alpha-COP(CTD) x epsilon-COP complex forms heterodimers in solution, and we demonstrate biochemically that the heterodimer directly interacts with the Dsl1 tethering complex. These data suggest that the heterodimer is exposed on COPI vesicles, while the remaining part of the B-subcomplex oligomerizes underneath into a cage.
Collapse
|
26
|
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
|
27
|
Papanikou E, Glick BS. The yeast Golgi apparatus: insights and mysteries. FEBS Lett 2009; 583:3746-51. [PMID: 19879270 DOI: 10.1016/j.febslet.2009.10.072] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2009] [Revised: 10/26/2009] [Accepted: 10/27/2009] [Indexed: 11/28/2022]
Abstract
The Golgi apparatus is known to modify and sort newly synthesized secretory proteins. However, fundamental mysteries remain about the structure, operation, and dynamics of this organelle. Important insights have emerged from studying the Golgi in yeasts. For example, yeasts have provided direct evidence for Golgi cisternal maturation, a mechanism that is likely to be broadly conserved. Here, we highlight features of the yeast Golgi as well as challenges that lie ahead.
Collapse
Affiliation(s)
- Effrosyni Papanikou
- The University of Chicago, Molecular Genetics and Cell Biology, 920 East 58th St., Chicago, IL 60637, USA
| | | |
Collapse
|
28
|
Kano F, Yamauchi S, Yoshida Y, Watanabe-Takahashi M, Nishikawa K, Nakamura N, Murata M. Yip1A regulates the COPI-independent retrograde transport from the Golgi complex to the ER. J Cell Sci 2009; 122:2218-27. [PMID: 19509059 DOI: 10.1242/jcs.043414] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Yip1A, a mammalian homologue of yeast Yip1p, is a multi-spanning membrane protein that is considered to be involved in transport between the endoplasmic reticulum (ER) and the Golgi. However, the precise role of Yip1A in mammalian cells remains unclear. We show here that endogenous Yip1A is localized to the ER-Golgi intermediate compartment (ERGIC). Knockdown of Yip1A by RNAi did not induce morphological changes in the Golgi, ER, or ERGIC. By analyzing a number of intracellular transport pathways, we found that Yip1A knockdown delayed the transport of Shiga toxin from the Golgi to the ER, but did not affect the anterograde transport of VSVGts045. We also found that a recombinant protein that corresponded to the N-terminal domain of Yip1A inhibited the COPI-independent retrograde transport of GFP-tagged galactosyltransferase, GT-GFP, but not the COPI-dependent retrograde transport of p58/ERGIC53. Furthermore, we found that Yip1A knockdown resulted in the dissociation of Rab6 from the membranes. These results suggested that Yip1A has a role in COPI-independent retrograde transport from the Golgi to the ER and regulates the membrane recruitment of Rab6.
Collapse
Affiliation(s)
- Fumi Kano
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo 153-8902, Japan
| | | | | | | | | | | | | |
Collapse
|
29
|
Grieder NC, Caussinus E, Parker DS, Cadigan K, Affolter M, Luschnig S. gammaCOP is required for apical protein secretion and epithelial morphogenesis in Drosophila melanogaster. PLoS One 2008; 3:e3241. [PMID: 18802472 PMCID: PMC2532760 DOI: 10.1371/journal.pone.0003241] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2008] [Accepted: 08/20/2008] [Indexed: 11/19/2022] Open
Abstract
Background There is increasing evidence that tissue-specific modifications of basic cellular functions play an important role in development and disease. To identify the functions of COPI coatomer-mediated membrane trafficking in Drosophila development, we were aiming to create loss-of-function mutations in the γCOP gene, which encodes a subunit of the COPI coatomer complex. Principal Findings We found that γCOP is essential for the viability of the Drosophila embryo. In the absence of zygotic γCOP activity, embryos die late in embryogenesis and display pronounced defects in morphogenesis of the embryonic epidermis and of tracheal tubes. The coordinated cell rearrangements and cell shape changes during tracheal tube morphogenesis critically depend on apical secretion of certain proteins. Investigation of tracheal morphogenesis in γCOP loss-of-function mutants revealed that several key proteins required for tracheal morphogenesis are not properly secreted into the apical lumen. As a consequence, γCOP mutants show defects in cell rearrangements during branch elongation, in tube dilation, as well as in tube fusion. We present genetic evidence that a specific subset of the tracheal defects in γCOP mutants is due to the reduced secretion of the Zona Pellucida protein Piopio. Thus, we identified a critical target protein of COPI-dependent secretion in epithelial tube morphogenesis. Conclusions/Significance These studies highlight the role of COPI coatomer-mediated vesicle trafficking in both general and tissue-specific secretion in a multicellular organism. Although COPI coatomer is generally required for protein secretion, we show that the phenotypic effect of γCOP mutations is surprisingly specific. Importantly, we attribute a distinct aspect of the γCOP phenotype to the effect on a specific key target protein.
Collapse
Affiliation(s)
- Nicole C Grieder
- Abteilung Zellbiologie, Biozentrum der Universität Basel, Basel, Switzerland.
| | | | | | | | | | | |
Collapse
|
30
|
Aspergillus nidulans hypB encodes a Sec7-domain protein important for hyphal morphogenesis. Fungal Genet Biol 2008; 45:749-59. [DOI: 10.1016/j.fgb.2007.11.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2007] [Revised: 11/07/2007] [Accepted: 11/19/2007] [Indexed: 01/31/2023]
|
31
|
Jain P, Mostoller K, Flaig KE, Ahuja J, Lepoutre V, Alefantis T, Khan ZK, Wigdahl B. Identification of Human T Cell Leukemia Virus Type 1 Tax Amino Acid Signals and Cellular Factors Involved in Secretion of the Viral Oncoprotein. J Biol Chem 2007; 282:34581-93. [PMID: 17897946 DOI: 10.1074/jbc.m707317200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Human T cell leukemia virus type 1 (HTLV-1) is the etiologic agent of a number of pathologic abnormalities, including adult T cell leukemia (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The viral oncoprotein Tax has been implicated in the pathogenesis of these diseases. Recently, cell-free Tax was detected in the cerebrospinal fluid of HAM/TSP patients, implying that extracellular Tax may be relevant to neurologic disease. Additionally, the presence of a nuclear export signal within Tax and its active secretion has been demonstrated in vitro. However, the mechanism of Tax secretion remains to be established. Studies reported herein elucidate the process of Tax secretion and identify domains of Tax critical to its subcellular localization and secretion. Tax was shown to interact with a number of cellular secretory pathway proteins in both the model cell line BHK (baby hamster kidney)-21 and an HTLV-1-infected T cell line, C8166, physiologically relevant to HTLV-1-induced disease. Silencing of selected components of the secretory pathway affected Tax secretion, further confirming regulated secretion of Tax. Additionally, mutations in two putative secretory signals within Tax DHE and YTNI resulted in aberrant subcellular localization of Tax and significantly altered protein secretion. Together, these studies demonstrate that Tax secretion is a regulated event facilitated by its interactions with proteins of the cellular secretory pathway and the presence of secretory signals within the carboxyl-terminal domain of the protein.
Collapse
MESH Headings
- Animals
- Cricetinae
- Gene Products, tax/cerebrospinal fluid
- Gene Products, tax/genetics
- Gene Products, tax/metabolism
- Gene Silencing
- Human T-lymphotropic virus 1/genetics
- Human T-lymphotropic virus 1/metabolism
- Human T-lymphotropic virus 1/pathogenicity
- Humans
- Jurkat Cells
- Leukemia-Lymphoma, Adult T-Cell/cerebrospinal fluid
- Leukemia-Lymphoma, Adult T-Cell/genetics
- Leukemia-Lymphoma, Adult T-Cell/virology
- Nuclear Export Signals/physiology
- Paraparesis, Tropical Spastic/cerebrospinal fluid
- Paraparesis, Tropical Spastic/genetics
- Paraparesis, Tropical Spastic/virology
- Protein Structure, Tertiary/physiology
- Protein Transport/physiology
Collapse
Affiliation(s)
- Pooja Jain
- Department of Microbiology and Immunology, Center for Molecular Virology and Neuroimmunology, Drexel University College of Medicine, 2900 Queen Lane, Philadelphia, PA 19129, USA
| | | | | | | | | | | | | | | |
Collapse
|
32
|
Villanueva RA, Rouillé Y, Dubuisson J. Interactions between virus proteins and host cell membranes during the viral life cycle. ACTA ACUST UNITED AC 2006; 245:171-244. [PMID: 16125548 PMCID: PMC7112339 DOI: 10.1016/s0074-7696(05)45006-8] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The structure and function of cells are critically dependent on membranes, which not only separate the interior of the cell from its environment but also define the internal compartments. It is therefore not surprising that the major steps of the life cycle of viruses of animals and plants also depend on cellular membranes. Indeed, interactions of viral proteins with host cell membranes are important for viruses to enter into host cells, replicate their genome, and produce progeny particles. To replicate its genome, a virus first needs to cross the plasma membrane. Some viruses can also modify intracellular membranes of host cells to create a compartment in which genome replication will take place. Finally, some viruses acquire an envelope, which is derived either from the plasma membrane or an internal membrane of the host cell. This paper reviews recent findings on the interactions of viral proteins with host cell membranes during the viral life cycle.
Collapse
Affiliation(s)
- Rodrigo A Villanueva
- CNRS-UPR2511, Institut de Biologie de Lille, Institut Pasteur de Lille, 59021 Lille Cedex, France
| | | | | |
Collapse
|
33
|
Ungar D, Oka T, Krieger M, Hughson FM. Retrograde transport on the COG railway. Trends Cell Biol 2006; 16:113-20. [PMID: 16406524 DOI: 10.1016/j.tcb.2005.12.004] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2005] [Revised: 10/21/2005] [Accepted: 12/12/2005] [Indexed: 11/18/2022]
Abstract
The conserved oligomeric Golgi (COG) complex is essential for establishing and/or maintaining the structure and function of the Golgi apparatus. The Golgi apparatus, in turn, has a central role in protein sorting and glycosylation within the eukaryotic secretory pathway. As a consequence, COG mutations can give rise to human genetic diseases known as congenital disorders of glycosylation. We review recent results from studies of yeast, worm, fly and mammalian COG that provide evidence that COG might function in retrograde vesicular trafficking within the Golgi apparatus. This hypothesis explains the impact of COG mutations by postulating that they impair the retrograde flow of resident Golgi proteins needed to maintain normal Golgi structure and function.
Collapse
Affiliation(s)
- Daniel Ungar
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | | | | | | |
Collapse
|
34
|
Grieder NC, Kloter U, Gehring WJ. Expression of COPI components during development of Drosophila melanogaster. Gene Expr Patterns 2005; 6:11-21. [PMID: 16169286 DOI: 10.1016/j.modgep.2005.06.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2005] [Revised: 05/29/2005] [Accepted: 06/04/2005] [Indexed: 01/02/2023]
Abstract
In a P{lArB} enhancer detector collection, a line was found that showed upregulated expression within centrally to posteriorly located germarial cysts. It was inserted in the gammaCOP locus on chromosome 3R. GammaCOP is a component of the COPI coatomer involved in membrane traffic. Most of the other known components of the COPI coatomer also showed higher expression in the posterior half of the germarium. Not only meiotic germline cysts but also migrating follicle cells upregulate the COPI subunits. During embryonic and larval development, the COPI subunits are expressed ubiquitously as expected for genes required for cell viability. In addition, they are strongly expressed in the salivary glands and the proventriculus. Whether tissue-specific transcriptional upregulation of COPI subunits is required for the reorganization of membranous compartments that are needed for the developmental processes that confer cyst polarity and follicle maturation will have to be addressed in a genetic study.
Collapse
Affiliation(s)
- Nicole C Grieder
- Biozentrum der Universität Basel, Abteilung Zellbiologie, Klingelbergstrasse 50-70, CH-4056 Basel, Switzerland.
| | | | | |
Collapse
|
35
|
Valdivia RH. Modeling the function of bacterial virulence factors in Saccharomyces cerevisiae. EUKARYOTIC CELL 2005; 3:827-34. [PMID: 15302815 PMCID: PMC500883 DOI: 10.1128/ec.3.4.827-834.2004] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Raphael H Valdivia
- Mailing address: Department of Molecular Genetics and Microbiology, Center for Microbial Pathogenesis, Duke University Medical Center, Durham, NC 27710, USA.
| |
Collapse
|
36
|
Ungar D, Oka T, Vasile E, Krieger M, Hughson FM. Subunit Architecture of the Conserved Oligomeric Golgi Complex. J Biol Chem 2005; 280:32729-35. [PMID: 16020545 DOI: 10.1074/jbc.m504590200] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The conserved oligomeric Golgi (COG) complex is thought to function in intra-Golgi retrograde trafficking mediated by coat protein I vesicles, a pathway essential for the proper structure and function of the Golgi apparatus. Previous work suggested that COG might act as a tethering factor to mediate the initial attachment between coat protein I vesicles and Golgi membranes. Here, we present extensive in vitro co-translation and immunoprecipitation experiments leading to a new model for the overall architecture of the mammalian COG complex. The eight COG subunits (Cog1-8) are found to form two heterotrimeric subassemblies (Cog2/3/4 and Cog5/6/7) linked by a heterodimer composed of the remaining subunits (Cog1/8). This model is in excellent agreement with in vivo data presented in an accompanying paper (Oka, T., Vasile, E., Penman, M., Novina, C. D., Dykxhoorn, D. M., Ungar, D., Hughson, F. M., and Krieger, M. (2005) J. Biol. Chem. 280, 32736-32745).
Collapse
Affiliation(s)
- Daniel Ungar
- Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544, USA
| | | | | | | | | |
Collapse
|
37
|
Ottschytsch N, Raes AL, Timmermans JP, Snyders DJ. Domain analysis of Kv6.3, an electrically silent channel. J Physiol 2005; 568:737-47. [PMID: 16096342 PMCID: PMC1464172 DOI: 10.1113/jphysiol.2005.090142] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The subunit Kv6.3 encodes a voltage-gated potassium channel belonging to the group of electrically silent Kv subunits, i.e. subunits that do not form functional homotetrameric channels. The lack of current, caused by retention in the endoplasmic reticulum (ER), was overcome by coexpression with Kv2.1. To investigate whether a specific section of Kv6.3 was responsible for ER retention, we constructed chimeric subunits between Kv6.3 and Kv2.1, and analysed their subcellular localization and functionality. The results demonstrate that the ER retention of Kv6.3 is not caused by the N-terminal A and B box (NAB) domain nor the intracellular N- or C-termini, but rather by the S1-S6 core protein. Introduction of individual transmembrane segments of Kv6.3 in Kv2.1 was tolerated, with the exception of S6. Indeed, introduction of the S6 domain of Kv6.3 in Kv2.1 was enough to cause ER retention, which was due to the C-terminal section of S6. The S4 segment of Kv6.3 could act as a voltage sensor in the Kv2.1 context, albeit with a major hyperpolarizing shift in the voltage dependence of activation and inactivation, apparently caused by the presence of a tyrosine in Kv6.3 instead of a conserved arginine. This study suggests that the silent behaviour of Kv6.3 is largely caused by the C-terminal part of its sixth transmembrane domain that causes ER retention of the subunit.
Collapse
Affiliation(s)
- Natacha Ottschytsch
- Laboratory for Molecular Biophysics, Physiology and Pharmacology, Department of Biomedical Sciences, University of Antwerp (CDE), Universiteitsplein 1, T4.21, 2610 Antwerp, Belgium
| | | | | | | |
Collapse
|
38
|
Agaphonov MO, Sokolov SS, Romanova NV, Sohn JH, Kim SY, Kalebina TS, Choi ES, Ter-Avanesyan MD. Mutation of the protein-O-mannosyltransferase enhances secretion of the human urokinase-type plasminogen activator inHansenula polymorpha. Yeast 2005; 22:1037-47. [PMID: 16200504 DOI: 10.1002/yea.1297] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Human urokinase-type plasminogen activator (uPA) is poorly secreted and aggregates in the endoplasmic reticulum of yeast cells due to inefficient folding. A screen for Hansenula polymorpha mutants with improved uPA secretion revealed a gene encoding a homologue of the Saccharomyces cerevisiae protein-O-mannosyltransferase Pmt1p. Expression of the H. polymorpha PMT1 gene (HpPMT1) abolished temperature sensitivity of the S. cerevisiae pmt1 pmt2 double mutant. As in S. cerevisiae, inactivation of the HpPMT1 gene affected electrophoretic mobility of the O-glycosylated protein, extracellular chitinase. In contrast to S. cerevisiae, disruption of HpPMT1 alone caused temperature sensitivity. Inactivation of the HpPMT1 gene decreased intracellular aggregation of uPA, suggesting that enhanced secretion of uPA was due to improvement of its folding in the endoplasmic reticulum. Unlike most of the endoplasmic reticulum membrane proteins, HpPmt1p possesses the C-terminal KDEL retention signal.
Collapse
Affiliation(s)
- Michael O Agaphonov
- Institute of Experimental Cardiology, Cardiology Research Center, 3rd Cherepkovskaya Str. 15A, Moscow 121552, Russia.
| | | | | | | | | | | | | | | |
Collapse
|
39
|
Chechenova MB, Romanova NV, Deev AV, Packeiser AN, Smirnov VN, Agaphonov MO, Ter-Avanesyan MD. C-terminal truncation of alpha-COP affects functioning of secretory organelles and calcium homeostasis in Hansenula polymorpha. EUKARYOTIC CELL 2004; 3:52-60. [PMID: 14871936 PMCID: PMC329505 DOI: 10.1128/ec.3.1.52-60.2004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In eukaryotic cells, COPI vesicles retrieve resident proteins to the endoplasmic reticulum and mediate intra-Golgi transport. Here, we studied the Hansenula polymorpha homologue of the Saccharomyces cerevisiae RET1 gene, encoding alpha-COP, a subunit of the COPI protein complex. H. polymorpha ret1 mutants, which expressed truncated alpha-COP lacking more than 300 C-terminal amino acids, manifested an enhanced ability to secrete human urokinase-type plasminogen activator (uPA) and an inability to grow with a shortage of Ca2+ ions, whereas a lack of alpha-COP expression was lethal. The alpha-COP defect also caused alteration of intracellular transport of the glycosylphosphatidylinositol-anchored protein Gas1p, secretion of abnormal uPA forms, and reductions in the levels of Pmr1p, a Golgi Ca2+-ATPase. Overexpression of Pmr1p suppressed some ret1 mutant phenotypes, namely, Ca2+ dependence and enhanced uPA secretion. The role of COPI-dependent vesicular transport in cellular Ca2+ homeostasis is discussed.
Collapse
Affiliation(s)
- Maria B Chechenova
- Institute of Experimental Cardiology, Cardiology Research Center, 121552 Moscow, Russia
| | | | | | | | | | | | | |
Collapse
|
40
|
Lontok E, Corse E, Machamer CE. Intracellular targeting signals contribute to localization of coronavirus spike proteins near the virus assembly site. J Virol 2004; 78:5913-22. [PMID: 15140989 PMCID: PMC415842 DOI: 10.1128/jvi.78.11.5913-5922.2004] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Coronavirus budding at the endoplasmic reticulum-Golgi intermediate compartment (ERGIC) requires accumulation of the viral envelope proteins at this point in the secretory pathway. Here we demonstrate that the spike (S) protein from the group 3 coronavirus infectious bronchitis virus (IBV) contains a canonical dilysine endoplasmic reticulum retrieval signal (-KKXX-COOH) in its cytoplasmic tail. This signal can retain a chimeric reporter protein in the ERGIC and when mutated allows transport of the full-length S protein as well as the chimera to the plasma membrane. Interestingly, the IBV S protein also contains a tyrosine-based endocytosis signal in its cytoplasmic tail, suggesting that any S protein that escapes the ERGIC will be rapidly endocytosed when it reaches the plasma membrane. We also identified a novel dibasic motif (-KXHXX-COOH) in the cytoplasmic tails of S proteins from group 1 coronaviruses and from the newly identified coronavirus implicated in severe acute respiratory syndrome. This dibasic motif also retained a reporter protein in the ERGIC, similar to the dilysine motif in IBV S. The cytoplasmic tails of S proteins from group 2 coronaviruses lack an intracellular localization signal. The inherent differences in S-protein trafficking could point to interesting variations in pathogenesis of coronaviruses, since increased levels of surface S protein could promote syncytium formation and direct cell-to-cell spread of the infection.
Collapse
Affiliation(s)
- Erik Lontok
- Department of Cell Biology, The Johns Hopkins University School of Medicine, 725 N. Wolfe St., Baltimore, MD 21205, USA
| | | | | |
Collapse
|
41
|
Oka T, Ungar D, Hughson FM, Krieger M. The COG and COPI complexes interact to control the abundance of GEARs, a subset of Golgi integral membrane proteins. Mol Biol Cell 2004; 15:2423-35. [PMID: 15004235 PMCID: PMC404034 DOI: 10.1091/mbc.e03-09-0699] [Citation(s) in RCA: 118] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The conserved oligomeric Golgi (COG) complex is a soluble hetero-octamer associated with the cytoplasmic surface of the Golgi. Mammalian somatic cell mutants lacking the Cog1 (ldlB) or Cog2 (ldlC) subunits exhibit pleiotropic defects in Golgi-associated glycoprotein and glycolipid processing that suggest COG is involved in the localization, transport, and/or function of multiple Golgi processing proteins. We have identified a set of COG-sensitive, integral membrane Golgi proteins called GEARs (mannosidase II, GOS-28, GS15, GPP130, CASP, giantin, and golgin-84) whose abundances were reduced in the mutant cells and, in some cases, increased in COG-overexpressing cells. In the mutants, some GEARs were abnormally localized in the endoplasmic reticulum and were degraded by proteasomes. The distributions of the GEARs were altered by small interfering RNA depletion of epsilon-COP in wild-type cells under conditions in which COG-insensitive proteins were unaffected. Furthermore, synthetic phenotypes arose in mutants deficient in both epsilon-COP and either Cog1 or Cog2. COG and COPI may work in concert to ensure the proper retention or retrieval of a subset of proteins in the Golgi, and COG helps prevent the endoplasmic reticulum accumulation and degradation of some GEARs.
Collapse
Affiliation(s)
- Toshihiko Oka
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | | | | | | |
Collapse
|
42
|
Abstract
COPI-coated vesicles mediate retrograde transport from the Golgi back to the ER and intra-Golgi transport. The cytosolic precursor of the COPI coat, the heptameric coatomer complex, can be thought of as composed of two subcomplexes. The first consists of the beta-, gamma-, delta- and zeta-COP subunits which are distantly homologous to AP clathrin adaptor subunits. The second consists of the alpha-, beta'- and epsilon-COP subunits. Here, we present the structure of the appendage domain of gamma-COP and show that it has a similar overall fold as the alpha-appendage of AP2. Again, like the alpha-appendage the gamma-COP appendage possesses a single protein/protein interaction site on its platform subdomain. We show that in yeast this site binds to the ARFGAP Glo3p, and in mammalian gamma-COP this site binds to a Glo3p orthologue, ARFGAP2. On the basis of mutations in the yeast homologue of gamma-COP, Sec21p, a second binding site is proposed to exist on the gamma-COP appendage that interacts with the alpha,beta',epsilon COPI subcomplex.
Collapse
Affiliation(s)
- Peter J Watson
- Cambridge Institute for Medical Research & Department of Clinical Biochemistry, University of Cambridge, Hills Road, Cambridge CB2 2XY, UK
| | | | | | | | | |
Collapse
|
43
|
Eugster A, Frigerio G, Dale M, Duden R. The alpha- and beta'-COP WD40 domains mediate cargo-selective interactions with distinct di-lysine motifs. Mol Biol Cell 2003; 15:1011-23. [PMID: 14699056 PMCID: PMC363058 DOI: 10.1091/mbc.e03-10-0724] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Coatomer is required for the retrieval of proteins from an early Golgi compartment back to the endoplasmic reticulum. The WD40 domain of alpha-COP is required for the recruitment of KKTN-tagged proteins into coatomer-coated vesicles. However, lack of the domain has only minor effects on growth in yeast. Here, we show that the WD40 domain of beta'-COP is required for the recycling of the KTKLL-tagged Golgi protein Emp47p. The protein is degraded more rapidly in cells with a point mutation in the WD40 domain of beta'-COP (sec27-95) or in cells lacking the domain altogether, whereas a point mutation in the Clathrin Heavy Chain Repeat (sec27-1) does not affect the turnover of Emp47p. Lack of the WD40 domain of beta'-COP has only minor effects on growth of yeast cells; however, absence of both WD40 domains of alpha- and beta'-COP is lethal. Two hybrid studies together with our analysis of the maturation of KKTN-tagged invertase and the turnover of Emp47p in alpha- and beta'-COP mutants suggest that the two WD40 domains of alpha- and beta'-COP bind distinct but overlapping sets of di-lysine signals and hence both contribute to recycling of proteins with di-lysine signals.
Collapse
Affiliation(s)
- Anne Eugster
- Department of Clinical Biochemistry, Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 2XY, United Kingdom
| | | | | | | |
Collapse
|
44
|
Wickert H, Rohrbach P, Scherer SJ, Krohne G, Lanzer M. A putative Sec23 homologue of Plasmodium falciparum is located in Maurer's clefts. Mol Biochem Parasitol 2003; 129:209-13. [PMID: 12850265 DOI: 10.1016/s0166-6851(03)00117-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Hannes Wickert
- Divison of Electron Microscopy, Biocenter of the University of Würzburg, Am Hubland, D-97094 Würzburg, Germany
| | | | | | | | | |
Collapse
|
45
|
Abstract
COP I and COP II coat proteins direct protein and membrane trafficking in between early compartments of the secretory pathway in eukaryotic cells. These coat proteins perform the dual, essential tasks of selecting appropriate cargo proteins and deforming the lipid bilayer of appropriate donor membranes into buds and vesicles. COP II proteins are required for selective export of newly synthesized proteins from the endoplasmic reticulum (ER). COP I proteins mediate a retrograde transport pathway that selectively recycles proteins from the cis-Golgi complex to the ER. Additionally, COP I coat proteins have complex functions in intra-Golgi trafficking and in maintaining the normal structure of the mammalian interphase Golgi complex.
Collapse
Affiliation(s)
- Rainer Duden
- Cambridge Institute for Medical Research, Department of Clinical Biochemistry, University of Cambridge, Hills Road, Cambridge CB2 2XY, UK.
| |
Collapse
|
46
|
Washburn MP, Koller A, Oshiro G, Ulaszek RR, Plouffe D, Deciu C, Winzeler E, Yates JR. Protein pathway and complex clustering of correlated mRNA and protein expression analyses in Saccharomyces cerevisiae. Proc Natl Acad Sci U S A 2003; 100:3107-12. [PMID: 12626741 PMCID: PMC152254 DOI: 10.1073/pnas.0634629100] [Citation(s) in RCA: 300] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2002] [Indexed: 11/18/2022] Open
Abstract
The mRNA and protein expression in Saccharomyces cerevisiae cultured in rich or minimal media was analyzed by oligonucleotide arrays and quantitative multidimensional protein identification technology. The overall correlation between mRNA and protein expression was weakly positive with a Spearman rank correlation coefficient of 0.45 for 678 loci. To place the data sets in a proper biological context, a clustering approach based on protein pathways and protein complexes was implemented. Protein expression levels were transcriptionally controlled for not only single loci but for entire protein pathways (e.g., Met, Arg, and Leu biosynthetic pathways). In contrast, the protein expression of loci in several protein complexes (e.g., SPT, COPI, and ribosome) was posttranscriptionally controlled. The coupling of the methods described provided insight into the biology of S. cerevisiae and a clustering strategy by which future studies should be based.
Collapse
Affiliation(s)
- Michael P Washburn
- Proteomics, Torrey Mesa Research Institute, 3115 Merryfield Row, San Diego, CA 92121, USA.
| | | | | | | | | | | | | | | |
Collapse
|
47
|
Ram RJ, Li B, Kaiser CA. Identification of Sec36p, Sec37p, and Sec38p: components of yeast complex that contains Sec34p and Sec35p. Mol Biol Cell 2002; 13:1484-500. [PMID: 12006647 PMCID: PMC111121 DOI: 10.1091/mbc.01-10-0495] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The Saccharomyces cerevisiae proteins Sec34p and Sec35p are components of a large cytosolic complex involved in protein transport through the secretory pathway. Characterization of a new secretion mutant led us to identify SEC36, which encodes a new component of this complex. Sec36p binds to Sec34p and Sec35p, and mutation of SEC36 disrupts the complex, as determined by gel filtration. Missense mutations of SEC36 are lethal with mutations in COPI subunits, indicating a functional connection between the Sec34p/sec35p complex and the COPI vesicle coat. Affinity purification of proteins that bind to Sec35p-myc allowed identification of two additional proteins in the complex. We call these two conserved proteins Sec37p and Sec38p. Disruption of either SEC37 or SEC38 affects the size of the complex that contains Sec34p and Sec35p. We also examined COD4, COD5, and DOR1, three genes recently reported to encode proteins that bind to Sec35p. Each of the eight genes that encode components of the Sec34p/sec35p complex was tested for its contribution to cell growth, protein transport, and the integrity of the complex. These tests indicate two general types of subunits: Sec34p, Sec35p, Sec36p, and Sec38p seem to form the essential core of a complex to which Sec37p, Cod4p, Cod5p, and Dor1p seem to be peripherally attached.
Collapse
Affiliation(s)
- Rachna J Ram
- Department of Biology, Massachusetts Institute of Technology, Cambridge 02139, USA
| | | | | |
Collapse
|
48
|
Bermak JC, Li M, Bullock C, Weingarten P, Zhou QY. Interaction of gamma-COP with a transport motif in the D1 receptor C-terminus. Eur J Cell Biol 2002; 81:77-85. [PMID: 11893085 DOI: 10.1078/0171-9335-00222] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Truncations at the carboxyl termini of G protein-coupled receptors result in defective receptor biogenesis and comprise a number of inherited disorders. In order to evaluate the structural role of the C-terminus in G protein-coupled receptor biogenesis, we generated a series of deletion and substitution mutations in the dopamine D1 receptor and visualized receptor subcellular localization by fusion to a green fluorescent protein. Alanine substitutions of several hydrophobic residues within the proximal C-terminus resulted in receptor transport arrest in the ER. Agonist binding and coupling to adenylyl cyclase was also abolished. In contrast, substitutions conserving C-terminal hydrophobicity produced normal cell surface receptor expression, binding, and stimulatory function. A mechanism for the role of the C-terminus in D1 receptor transport was investigated by searching for candidate protein interactions. The D1 receptor was found to co-precipitate and associate in vitro directly with the gamma-subunit of the COPI coatomer complex. In vitro pull-down assays confirmed that only the D1 C-terminus is required for COPI association, and that identical mutations causing disruption of receptor transport to the cell surface also disrupted binding to COPI. Furthermore, conservative mutations in the D1 C-terminus restored COPI association just as they restored cell surface transport. These results suggest that association between the coatomer complex and hydrophobic residues within the proximal C-terminus of the D1 receptor may serve an important role in receptor transport.
Collapse
Affiliation(s)
- Jason C Bermak
- Department of Pharmacology, University of California, Irvine 92697, USA
| | | | | | | | | |
Collapse
|
49
|
Abstract
Here we report the identification of SGF1 as a high-copy suppressor of the sec35-1 mutant. SGF1 encodes an essential hydrophilic protein of approximately 100 kDa. Using the yeast two-hybrid system and coprecipitation studies, we demonstrate that Sgf1p is a new subunit of the multiprotein Sec34p/Sec35p complex. Reduced levels of Sgf1p lead to the accumulation of a variety of membranes as well as a kinetic block in endoplasmic reticulum to Golgi traffic. Immunofluorescence studies demonstrate that Sec34p is found throughout the Golgi, with a high concentration on early Golgi. Although an earlier study suggested that Sec34p (Grd20p) is not required for protein secretion, we show here that the sec34-2 and sec35-1 mutations lead to a pleiotropic block in the secretion of all proteins into the growth medium.
Collapse
Affiliation(s)
- D W Kim
- Department of Cell Biology and Howard Hughes Medical Institute, Yale University, New Haven, CT, USA
| | | | | | | | | |
Collapse
|
50
|
Majoul I, Straub M, Hell SW, Duden R, Söling HD. KDEL-cargo regulates interactions between proteins involved in COPI vesicle traffic: measurements in living cells using FRET. Dev Cell 2001; 1:139-53. [PMID: 11703931 DOI: 10.1016/s1534-5807(01)00004-1] [Citation(s) in RCA: 145] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
How the occupied KDEL receptor ERD2 is sorted into COPI vesicles for Golgi-to-ER transport is largely unknown. Here, interactions between proteins of the COPI transport machinery occurring during a "wave" of transport of a KDEL ligand were studied in living cells. FRET between CFP and YFP fusion proteins was measured by multifocal multiphoton microscopy and bulk-cell spectrofluorimetry. Ligand binding induces oligomerization of ERD2 and recruitment of ARFGAP to the Golgi, where the (ERD2)n/ARFGAP complex interacts with membrane-bound ARF1. During KDEL ligand transport, interactions of ERD2 with beta-COP and p23 decrease and the proteins segregate. Both p24a and p23 interact with ARF1, but only p24 interacts with ARFGAP. These findings suggest a model for how cargo-induced oligomerization of ERD2 regulates its sorting into COPI-coated buds.
Collapse
Affiliation(s)
- I Majoul
- Department of Neurobiology, Max-Planck-Institute of Biophysical Chemistry, Göttingen, Germany
| | | | | | | | | |
Collapse
|