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Li J, Guo B, Zhang W, Yue S, Huang S, Gao S, Ma J, Cipollo JF, Yang S. Recent advances in demystifying O-glycosylation in health and disease. Proteomics 2022; 22:e2200156. [PMID: 36088641 DOI: 10.1002/pmic.202200156] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Revised: 08/30/2022] [Accepted: 09/02/2022] [Indexed: 11/09/2022]
Abstract
O-Glycosylation is one of the most common protein post-translational modifications (PTM) and plays an essential role in the pathophysiology of diseases. However, the complexity of O-glycosylation and the lack of specific enzymes for the processing of O-glycans and their O-glycopeptides make O-glycosylation analysis challenging. Recently, research on O-glycosylation has received attention owing to technological innovation and emerging O-glycoproteases. Several serine/threonine endoproteases have been found to specifically cleave O-glycosylated serine or threonine, allowing for the systematic analysis of O-glycoproteins. In this review, we first assessed the field of protein O-glycosylation over the past decade and used bibliometric analysis to identify keywords and emerging trends. We then summarized recent advances in O-glycosylation, covering several aspects: O-glycan release, site-specific elucidation of intact O-glycopeptides, identification of O-glycosites, characterization of different O-glycoproteases, mass spectrometry (MS) fragmentation methods for site-specific O-glycosylation assignment, and O-glycosylation data analysis. Finally, the role of O-glycosylation in health and disease was discussed.
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Affiliation(s)
- Jiajia Li
- Center for Clinical Mass Spectrometry, College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu, China
| | - Bo Guo
- Jiangsu Key Laboratory of Marine Pharmaceutical Compound Screening, Jiangsu Key Laboratory of Marine Biological Resources and Environment, Co-Innovation Center of Jiangsu Marine Bio-industry Technology, School of Pharmacy, Jiangsu Ocean University, Lianyungang, China
| | - Wenqi Zhang
- Center for Clinical Mass Spectrometry, College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu, China
| | - Shuang Yue
- Center for Clinical Mass Spectrometry, College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu, China
| | - Shan Huang
- Center for Clinical Mass Spectrometry, College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu, China
| | - Song Gao
- Jiangsu Key Laboratory of Marine Pharmaceutical Compound Screening, Jiangsu Key Laboratory of Marine Biological Resources and Environment, Co-Innovation Center of Jiangsu Marine Bio-industry Technology, School of Pharmacy, Jiangsu Ocean University, Lianyungang, China
| | - Junfeng Ma
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Georgetown University, Washington, DC, USA
| | - John F Cipollo
- Laboratory of Bacterial Polysaccharides, Division of Bacterial, Parasitic and Allergenic Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, USA
| | - Shuang Yang
- Center for Clinical Mass Spectrometry, College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu, China
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Valli M, Grillitsch K, Grünwald-Gruber C, Tatto NE, Hrobath B, Klug L, Ivashov V, Hauzmayer S, Koller M, Tir N, Leisch F, Gasser B, Graf AB, Altmann F, Daum G, Mattanovich D. A subcellular proteome atlas of the yeast Komagataella phaffii. FEMS Yeast Res 2021; 20:5700286. [PMID: 31922548 PMCID: PMC6981350 DOI: 10.1093/femsyr/foaa001] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 01/09/2020] [Indexed: 12/11/2022] Open
Abstract
The compartmentalization of metabolic and regulatory pathways is a common pattern of living organisms. Eukaryotic cells are subdivided into several organelles enclosed by lipid membranes. Organelle proteomes define their functions. Yeasts, as simple eukaryotic single cell organisms, are valuable models for higher eukaryotes and frequently used for biotechnological applications. While the subcellular distribution of proteins is well studied in Saccharomyces cerevisiae, this is not the case for other yeasts like Komagataella phaffii (syn. Pichia pastoris). Different to most well-studied yeasts, K. phaffii can grow on methanol, which provides specific features for production of heterologous proteins and as a model for peroxisome biology. We isolated microsomes, very early Golgi, early Golgi, plasma membrane, vacuole, cytosol, peroxisomes and mitochondria of K. phaffii from glucose- and methanol-grown cultures, quantified their proteomes by liquid chromatography-electrospray ionization-mass spectrometry of either unlabeled or tandem mass tag-labeled samples. Classification of the proteins by their relative enrichment, allowed the separation of enriched proteins from potential contaminants in all cellular compartments except the peroxisomes. We discuss differences to S. cerevisiae, outline organelle specific findings and the major metabolic pathways and provide an interactive map of the subcellular localization of proteins in K. phaffii.
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Affiliation(s)
- Minoska Valli
- Austrian Centre of Industrial Biotechnology (ACIB), Muthgasse 11, 1190 Vienna, Austria.,Department of Biotechnology, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, 1190 Vienna, Austria
| | - Karlheinz Grillitsch
- Austrian Centre of Industrial Biotechnology (ACIB), Muthgasse 11, 1190 Vienna, Austria
| | - Clemens Grünwald-Gruber
- Austrian Centre of Industrial Biotechnology (ACIB), Muthgasse 11, 1190 Vienna, Austria.,Department of Chemistry, University of Natural Resources and Life Sciences, Muthgasse 18, 1190 Vienna, Austria
| | - Nadine E Tatto
- Austrian Centre of Industrial Biotechnology (ACIB), Muthgasse 11, 1190 Vienna, Austria.,Department of Biotechnology, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, 1190 Vienna, Austria
| | - Bernhard Hrobath
- Institute of Statistics, University of Natural Resources and Life Sciences, Peter-Jordan-Straße 82, 1190 Vienna, Austria
| | - Lisa Klug
- Austrian Centre of Industrial Biotechnology (ACIB), Muthgasse 11, 1190 Vienna, Austria.,Institute of Biochemistry, Graz University of Technology, Petersgasse 12/II, 8010, Graz, Austria
| | - Vasyl Ivashov
- Institute of Biochemistry, Graz University of Technology, Petersgasse 12/II, 8010, Graz, Austria
| | - Sandra Hauzmayer
- School of Bioengineering, University of Applied Sciences FH-Campus Vienna, Muthgasse 11, 1190 Vienna, Austria
| | - Martina Koller
- School of Bioengineering, University of Applied Sciences FH-Campus Vienna, Muthgasse 11, 1190 Vienna, Austria
| | - Nora Tir
- Department of Biotechnology, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, 1190 Vienna, Austria
| | - Friedrich Leisch
- Austrian Centre of Industrial Biotechnology (ACIB), Muthgasse 11, 1190 Vienna, Austria.,Institute of Statistics, University of Natural Resources and Life Sciences, Peter-Jordan-Straße 82, 1190 Vienna, Austria
| | - Brigitte Gasser
- Austrian Centre of Industrial Biotechnology (ACIB), Muthgasse 11, 1190 Vienna, Austria.,Department of Biotechnology, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, 1190 Vienna, Austria
| | - Alexandra B Graf
- Austrian Centre of Industrial Biotechnology (ACIB), Muthgasse 11, 1190 Vienna, Austria.,School of Bioengineering, University of Applied Sciences FH-Campus Vienna, Muthgasse 11, 1190 Vienna, Austria
| | - Friedrich Altmann
- Austrian Centre of Industrial Biotechnology (ACIB), Muthgasse 11, 1190 Vienna, Austria.,Department of Chemistry, University of Natural Resources and Life Sciences, Muthgasse 18, 1190 Vienna, Austria
| | - Günther Daum
- Austrian Centre of Industrial Biotechnology (ACIB), Muthgasse 11, 1190 Vienna, Austria.,Institute of Biochemistry, Graz University of Technology, Petersgasse 12/II, 8010, Graz, Austria
| | - Diethard Mattanovich
- Austrian Centre of Industrial Biotechnology (ACIB), Muthgasse 11, 1190 Vienna, Austria.,Department of Biotechnology, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, 1190 Vienna, Austria
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3
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Golgi localization of glycosyltransferases requires Gpp74p in Schizosaccharomyces pombe. Appl Microbiol Biotechnol 2020; 104:8897-8909. [DOI: 10.1007/s00253-020-10881-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 08/24/2020] [Accepted: 09/02/2020] [Indexed: 12/20/2022]
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Gómez-Gaviria M, Lozoya-Pérez NE, Staniszewska M, Franco B, Niño-Vega GA, Mora-Montes HM. Loss of Kex2 Affects the Candida albicans Cell Wall and Interaction with Innate Immune Cells. J Fungi (Basel) 2020; 6:jof6020057. [PMID: 32365492 PMCID: PMC7344602 DOI: 10.3390/jof6020057] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 04/27/2020] [Accepted: 04/28/2020] [Indexed: 12/18/2022] Open
Abstract
The secretory pathway in Candida albicans involves the protein translocation into the lumen of the endoplasmic reticulum and transport to the Golgi complex, where proteins undergo posttranslational modifications, including glycosylation and proteolysis. The Golgi-resident Kex2 protease is involved in such processing and disruption of its encoding gene affected virulence and dimorphism. These previous studies were performed using cells without URA3 or with URA3 ectopically placed into the KEX2 locus. Since these conditions are known to affect the cellular fitness and the host-fungus interaction, here we generated a kex2Δ null mutant strain with URA3 placed into the neutral locus RPS1. The characterization of this strain showed defects in the cell wall composition, with a reduction in the N-linked mannan content, and the increment in the levels of O-linked mannans, chitin, and β-glucans. The defects in the mannan content are likely linked to changes in Golgi-resident enzymes, as the α-1,2-mannosyltransferase and α-1,6-mannosyltransferase activities were incremented and reduced, respectively. The mutant cells also showed reduced ability to stimulate cytokine production and phagocytosis by human mononuclear cells and macrophages, respectively. Collectively, these data showed that loss of Kex2 affected the cell wall composition, the protein glycosylation pathways, and interaction with innate immune cells.
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Affiliation(s)
- Manuela Gómez-Gaviria
- Departamento de Biología, División de Ciencias Naturales y Exactas, Campus Guanajuato, Universidad de Guanajuato, Guanajuato Gto 36050, Mexico; (M.G.-G.); (N.E.L.-P.); (B.F.); (G.A.N.-V.)
| | - Nancy E. Lozoya-Pérez
- Departamento de Biología, División de Ciencias Naturales y Exactas, Campus Guanajuato, Universidad de Guanajuato, Guanajuato Gto 36050, Mexico; (M.G.-G.); (N.E.L.-P.); (B.F.); (G.A.N.-V.)
| | - Monika Staniszewska
- Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland;
| | - Bernardo Franco
- Departamento de Biología, División de Ciencias Naturales y Exactas, Campus Guanajuato, Universidad de Guanajuato, Guanajuato Gto 36050, Mexico; (M.G.-G.); (N.E.L.-P.); (B.F.); (G.A.N.-V.)
| | - Gustavo A. Niño-Vega
- Departamento de Biología, División de Ciencias Naturales y Exactas, Campus Guanajuato, Universidad de Guanajuato, Guanajuato Gto 36050, Mexico; (M.G.-G.); (N.E.L.-P.); (B.F.); (G.A.N.-V.)
| | - Hector M. Mora-Montes
- Departamento de Biología, División de Ciencias Naturales y Exactas, Campus Guanajuato, Universidad de Guanajuato, Guanajuato Gto 36050, Mexico; (M.G.-G.); (N.E.L.-P.); (B.F.); (G.A.N.-V.)
- Correspondence: ; Tel.: +52-473-732-0006 (ext. 8193)
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Pothukuchi P, Agliarulo I, Russo D, Rizzo R, Russo F, Parashuraman S. Translation of genome to glycome: role of the Golgi apparatus. FEBS Lett 2019; 593:2390-2411. [PMID: 31330561 DOI: 10.1002/1873-3468.13541] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 07/12/2019] [Accepted: 07/15/2019] [Indexed: 12/16/2022]
Abstract
Glycans are one of the four biopolymers of the cell and they play important roles in cellular and organismal physiology. They consist of both linear and branched structures and are synthesized in a nontemplated manner in the secretory pathway of mammalian cells with the Golgi apparatus playing a key role in the process. In spite of the absence of a template, the glycans synthesized by a cell are not a random collection of possible glycan structures but a distribution of specific glycans in defined quantities that is unique to each cell type (Cell type here refers to distinct cell forms present in an organism that can be distinguished based on morphological, phenotypic and/or molecular criteria.) While information to produce cell type-specific glycans is encoded in the genome, how this information is translated into cell type-specific glycome (Glycome refers to the quantitative distribution of all glycan structures present in a given cell type.) is not completely understood. We summarize here the factors that are known to influence the fidelity of glycan biosynthesis and integrate them into known glycosylation pathways so as to rationalize the translation of genetic information to cell type-specific glycome.
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Affiliation(s)
- Prathyush Pothukuchi
- Institute of Biochemistry and Cellular Biology, National Research Council of Italy, Napoli, Italy
| | - Ilenia Agliarulo
- Institute of Biochemistry and Cellular Biology, National Research Council of Italy, Napoli, Italy
| | - Domenico Russo
- Institute of Biochemistry and Cellular Biology, National Research Council of Italy, Napoli, Italy
| | - Riccardo Rizzo
- Institute of Biochemistry and Cellular Biology, National Research Council of Italy, Napoli, Italy
| | - Francesco Russo
- Institute of Biochemistry and Cellular Biology, National Research Council of Italy, Napoli, Italy
| | - Seetharaman Parashuraman
- Institute of Biochemistry and Cellular Biology, National Research Council of Italy, Napoli, Italy
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Suntio T, Shiryaev SA, Makarow M. ATPase activity of a yeast secretory glycoprotein allows ER exit during inactivation of COPII components Sec24p and Sec13p. Yeast 2011; 28:453-65. [PMID: 21446055 DOI: 10.1002/yea.1850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2010] [Accepted: 02/15/2011] [Indexed: 11/07/2022] Open
Abstract
Proteins exit the endoplasmic reticulum (ER) in vesicles pinching off from the membrane at sites covered by the COPII coat, which consists of Sec23/24p and Sec13/31p. We have shown that the glycoprotein Hsp150 exits the ER in the absence of Sec13p or any member of the Sec24p family. The determinant responsible for this resides in the C-terminal domain of Hsp150 (CTD). Here, A- and B-type Walker motifs were identified in the CTD. Authentic Hsp150 from the yeast culture medium, as well as Hsp150 and the CTD fragment produced in Escherichia coli, exhibited ATPase activity nearly three times higher than the published activity of the ER chaperone Kar2p/BiP. Deletion of the Walker motif, and a K335A mutation in it, abolished the ATPase activity. Hsp150 homologues Pir3p and Pir4p, differing in critical amino acids of the Walker motif, also lacked ATPase activity. Unexpectedly, inactivation of the ATPase activity blocked ER exit of Hsp150 in the absence of Sec24p or Sec13p function, whereas secretion in normal cells was not compromised. To our knowledge this is the first documentation of the ATPase activity of a protein serving an intracellular transport function.
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Affiliation(s)
- Taina Suntio
- Programme in Cellular Biotechnology, Institute of Biotechnology, University of Helsinki, Finland.
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7
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Genome-wide identification of genes that play a role in boron stress response in yeast. Genomics 2011; 97:106-11. [DOI: 10.1016/j.ygeno.2010.10.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2010] [Revised: 10/21/2010] [Accepted: 10/22/2010] [Indexed: 11/21/2022]
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Lorente-Rodríguez A, Barlowe C. Requirement for Golgi-localized PI(4)P in fusion of COPII vesicles with Golgi compartments. Mol Biol Cell 2010; 22:216-29. [PMID: 21119004 PMCID: PMC3020917 DOI: 10.1091/mbc.e10-04-0317] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The role of specific membrane lipids in ER-Golgi transport is unclear. Using cell-free assays that measure stages in ER-Golgi transport, a variety of enzyme inhibitors, lipid-modifying enzymes, and lipid ligands were screened. The results indicate that PI(4)P is required for SNARE-dependent fusion of COPII vesicles with the Golgi complex. The role of specific membrane lipids in transport between endoplasmic reticulum (ER) and Golgi compartments is poorly understood. Using cell-free assays that measure stages in ER-to-Golgi transport, we screened a variety of enzyme inhibitors, lipid-modifying enzymes, and lipid ligands to investigate requirements in yeast. The pleckstrin homology (PH) domain of human Fapp1, which binds phosphatidylinositol-4-phosphate (PI(4)P) specifically, was a strong and specific inhibitor of anterograde transport. Analysis of wild type and mutant PH domain proteins in addition to recombinant versions of the Sac1p phosphoinositide-phosphatase indicated that PI(4)P was required on Golgi membranes for fusion with coat protein complex II (COPII) vesicles. PI(4)P inhibition did not prevent vesicle tethering but significantly reduced formation of soluble n-ethylmaleimide sensitive factor adaptor protein receptor (SNARE) complexes between vesicle and Golgi SNARE proteins. Moreover, semi-intact cell membranes containing elevated levels of the ER-Golgi SNARE proteins and Sly1p were less sensitive to PI(4)P inhibitors. Finally, in vivo analyses of a pik1 mutant strain showed that inhibition of PI(4)P synthesis blocked anterograde transport from the ER to early Golgi compartments. Together, the data presented here indicate that PI(4)P is required for the SNARE-dependent fusion stage of COPII vesicles with the Golgi complex.
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The cytoplasmic region of alpha-1,6-mannosyltransferase Mnn9p is crucial for retrograde transport from the Golgi apparatus to the endoplasmic reticulum in Saccharomyces cerevisiae. EUKARYOTIC CELL 2007; 7:310-8. [PMID: 18083825 DOI: 10.1128/ec.00333-07] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In Saccharomyces cerevisiae, Och1p and Mnn9p mannosyltransferases are localized in the cis-Golgi. Attempts to live image Och1p and Mnn9p tagged with green fluorescent protein or red fluorescent protein, respectively, using a high-performance confocal laser scanning microscope system resulted in simultaneous visualization of the native proteins in a living cell. Our observations revealed that Och1p and Mnn9p are not always colocalized to the same cisternae. The difference in the dynamics of these mannosyltransferases may reflect differences in the mechanisms for their retention in the cis-Golgi, since it has been reported that Mnn9p cycles between the endoplasmic reticulum and the cis-Golgi whereas Och1p does not (Z. Todorow, A. Spang, E. Carmack, J. Yates, and R. Schekman, Proc. Natl. Acad. Sci. USA 97:13643-13648, 2000). We investigated the localization of chimeric proteins of Mnn9p and Och1p in sec12 and erd1 mutant cells. A chimeric protein, M16/O16, which consists of the N-terminal cytoplasmic region of Mnn9p and the transmembrane and luminal region of Och1p, behaved like Mnn9p, suggesting that the N-terminal cytoplasmic region is important for the intracellular dynamics of Mnn9p. This observation is supported by results from subcellular-fractionation experiments. Mutational analysis revealed that two arginine residues in the N-terminal region of Mnn9p are important for the chimeric protein to cycle between the endoplasmic reticulum and the Golgi apparatus.
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Karhinen L, Bastos RN, Jokitalo E, Makarow M. Endoplasmic reticulum exit of a secretory glycoprotein in the absence of sec24p family proteins in yeast. Traffic 2005; 6:562-74. [PMID: 15941408 DOI: 10.1111/j.1600-0854.2005.00297.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Glycoproteins exit the endoplasmic reticulum (ER) of the yeast Saccharomyces cerevisiae in coat protein complex II (COPII) coated vesicles. The coat consists of the essential proteins Sec23p, Sec24p, Sec13p, Sec31p, Sar1p and Sec16p. Sec24p and its two nonessential homologues Sfb2p and Sfb3p have been suggested to serve in cargo selection. Using temperature-sensitive sec24-1 mutants, we showed previously that a secretory glycoprotein, Hsp150, does not require functional Sec24p for ER exit. Deletion of SFB2, SFB3 or both from wild type or the deletion of SFB2 from sec24-1 cells did not affect Hsp150 transport. SFB3 deletion has been reported to be lethal in sec24-1. However, here we constructed a sec24-1 Deltasfb3 and a sec24-1 Deltasfb2 Deltasfb3 strain and show that Hsp150 was secreted slowly in both. Turning off the SEC24 gene did not inhibit Hsp150 secretion either, and the lack of SEC24 expression in a Deltasfb2 Deltasfb3 deletant still allowed some secretion. The sec24-1 Deltasfb2 Deltasfb3 mutant grew slower than sec24-1. The cells were irregularly shaped, budded from random sites and contained proliferated ER at permissive temperature. At restrictive temperature, the ER formed carmellae-like proliferations. Our data indicate that ER exit may occur in vesicles lacking a full complement of Sec23p/24p and Sec13p/31p, demonstrating diversity in the composition of the COPII coat.
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Affiliation(s)
- Leena Karhinen
- Program in Cellular Biotechnology, Institute of Biotechnology, University of Helsinki, Helsinki, Finland.
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11
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Puthenveedu MA, Linstedt AD. Subcompartmentalizing the Golgi apparatus. Curr Opin Cell Biol 2005; 17:369-75. [PMID: 15975779 DOI: 10.1016/j.ceb.2005.06.006] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2005] [Accepted: 06/03/2005] [Indexed: 01/04/2023]
Abstract
The subcompartmentalized structure of the Golgi apparatus contributes to efficient glycosylation in the secretory pathway. Subcompartmentalization driven by maturation relies primarily on constant and accurate vesicle-mediated local recycling of Golgi residents. The precision of this vesicle transport is dependent on the interplay between the key factors that mediate vesicle budding and fusion--the coat proteins and the SNARE fusion machinery. These alone, however, may not be sufficient to ensure establishment of compartments de novo, and additional regulatory mechanisms operate to modify their activity.
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Park SK, Hartnell LM, Jackson CL. Mutations in a highly conserved region of the Arf1p activator GEA2 block anterograde Golgi transport but not COPI recruitment to membranes. Mol Biol Cell 2005; 16:3786-99. [PMID: 15930122 PMCID: PMC1182316 DOI: 10.1091/mbc.e05-04-0289] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
We have identified an important functional region of the yeast Arf1 activator Gea2p upstream of the catalytic Sec7 domain and characterized a set of temperature-sensitive (ts) mutants with amino acid substitutions in this region. These gea2-ts mutants block or slow transport of proteins traversing the secretory pathway at exit from the endoplasmic reticulum (ER) and the early Golgi, and accumulate both ER and early Golgi membranes. No defects in two types of retrograde trafficking/sorting assays were observed. We find that a substantial amount of COPI is associated with Golgi membranes in the gea2-ts mutants, even after prolonged incubation at the nonpermissive temperature. COPI in these mutants is released from Golgi membranes by brefeldin A, a drug that binds directly to Gea2p and blocks Arf1 activation. Our results demonstrate that COPI function in sorting of at least three retrograde cargo proteins within the Golgi is not perturbed in these mutants, but that forward transport is severely inhibited. Hence this region of Gea2p upstream of the Sec7 domain plays a role in anterograde transport that is independent of its role in recruiting COPI for retrograde transport, at least of a subset of Golgi-ER cargo.
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Affiliation(s)
- Sei-Kyoung Park
- Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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13
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Salo H, Sievi E, Suntio T, Mecklin M, Mattila P, Renkonen R, Makarow M. Co-expression of two mammalian glycosyltransferases in the yeast cell wall allows synthesis of sLex. FEMS Yeast Res 2005; 5:341-50. [PMID: 15691739 DOI: 10.1016/j.femsyr.2004.11.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2004] [Revised: 10/08/2004] [Accepted: 11/24/2004] [Indexed: 11/20/2022] Open
Abstract
Interactions between selectins and their oligosaccharide-decorated counter-receptors play an important role in the initiation of leukocyte extravasation in inflammation. L-selectin ligands are O-glycosylated with sulphated sialyl Lewis X epitopes (sulpho-sLex). Synthetic sLex oligosaccharides have been shown to inhibit adhesion of lymphocytes to endothelium at sites of inflammation. Thus, they could be used to prevent undesirable inflammatory reactions such as rejection of organ transplants. In vitro synthesis of sLex glycans is dependent on the availability of recombinant glycosyltransferases. Here we expressed the catalytic domain of human alpha-1,3-fucosyltransferase VII in the yeasts Saccharomyces cerevisiae and Pichia pastoris. To promote proper folding and secretion competence of this catalytic domain in yeast, it was fused to the Hsp150 delta carrier, which is an N-terminal fragment of a secretory glycoprotein of S. cerevisiae. In both yeasts, the catalytic domain acquired an active conformation and the fusion protein was externalised, but remained mostly attached to the cell wall in a non-covalent fashion. Incubation of intact S. cerevisiae or P. pastoris cells with GDP-[14C]fucose and sialyl-alpha-2,3-N-acetyllactosamine resulted in synthesis of radioactive sLex, which diffused to the medium. Finally, we constructed an S. cerevisiae strain co-expressing the catalytic domains of alpha-2,3-sialyltransferase and alpha-1,3-fucosyltransferase VII, which were targeted to the cell wall. When these cells were provided with N-acetyllactosamine, CMP-sialic acid and GDP-[14C]fucose, radioactive sLex was produced to the medium. These data imply that yeast cells can provide a self-perpetuating source of fucosyltransferase activity immobilized in the cell wall, useful for the in vitro synthesis of sLex.
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Affiliation(s)
- Hanna Salo
- Program in Cellular Biotechnology, Institute of Biotechnology, University of Helsinki, Viikinkaari 9, 00710 Helsinki, Finland.
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