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Nakanishi M, Takeguchi M, Takezaki R, Hino M, Nomoto H. Loss of complex-type N-linked glycans attenuates maximum cell density and susceptibility to human serum of Trypanosoma brucei brucei. Parasitol Int 2024; 101:102874. [PMID: 38417735 DOI: 10.1016/j.parint.2024.102874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 01/09/2024] [Accepted: 02/24/2024] [Indexed: 03/01/2024]
Abstract
Trypanosoma brucei brucei is a parasitic protist that expresses cell surface proteins modified with complex-type N-linked glycan (NLG), like multicellular organisms. However, little is known about the role of complex-type NLG. In T. b. brucei, it has been shown that either one of the glycosyltransferases, TbGT11 or TbGT15, is sufficient to initiate the synthesis of complex-type NLG. To clarify the role of complex-type NLG, it is necessary to generate cells lacking both enzymes. Therefore, we deleted TbGT11 and TbGT15 from the genome of T. b. brucei for the phenotypic examination. The mutant strain grew in culture, with reduced maximum cell density; showed decreased susceptibility to normal human serum, which contains trypanolytic factors; and lacked uptake of the haptoglobin-hemoglobin complex. These data indicate that protein modification by complex-type NLG is not essential but is required for receptor function.
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Affiliation(s)
- Masayuki Nakanishi
- Laboratory of Biochemistry, School of Pharmaceutical Sciences, Matsuyama University, Matsuyama, Ehime 790-8578, Japan.
| | - Masaki Takeguchi
- Laboratory of Biochemistry, School of Pharmaceutical Sciences, Matsuyama University, Matsuyama, Ehime 790-8578, Japan
| | - Reo Takezaki
- Laboratory of Biochemistry, School of Pharmaceutical Sciences, Matsuyama University, Matsuyama, Ehime 790-8578, Japan
| | - Mami Hino
- Laboratory of Biochemistry, School of Pharmaceutical Sciences, Matsuyama University, Matsuyama, Ehime 790-8578, Japan.
| | - Hiroshi Nomoto
- Laboratory of Biochemistry, School of Pharmaceutical Sciences, Matsuyama University, Matsuyama, Ehime 790-8578, Japan.
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2
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Duncan SM, Carbajo CG, Nagar R, Zhong Q, Breen C, Ferguson MAJ, Tiengwe C. Generation of a bloodstream form Trypanosoma brucei double glycosyltransferase null mutant competent in receptor-mediated endocytosis of transferrin. PLoS Pathog 2024; 20:e1012333. [PMID: 38935804 PMCID: PMC11236118 DOI: 10.1371/journal.ppat.1012333] [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: 04/09/2024] [Revised: 07/10/2024] [Accepted: 06/10/2024] [Indexed: 06/29/2024] Open
Abstract
The bloodstream form of Trypanosoma brucei expresses large poly-N-acetyllactosamine (pNAL) chains on complex N-glycans of a subset of glycoproteins. It has been hypothesised that pNAL may be required for receptor-mediated endocytosis. African trypanosomes contain a unique family of glycosyltransferases, the GT67 family. Two of these, TbGT10 and TbGT8, have been shown to be involved in pNAL biosynthesis in bloodstream form Trypanosoma brucei, raising the possibility that deleting both enzymes simultaneously might abolish pNAL biosynthesis and provide clues to pNAL function and/or essentiality. In this paper, we describe the creation of a TbGT10 null mutant containing a single TbGT8 allele that can be excised upon the addition of rapamycin and, from that, a TbGT10 and TbGT8 double null mutant. These mutants were analysed by lectin blotting, glycopeptide methylation linkage analysis and flow cytometry. The data show that the mutants are defective, but not abrogated, in pNAL synthesis, suggesting that other GT67 family members can compensate to some degree for loss of TbGT10 and TbGT8. Despite there being residual pNAL synthesis in these mutants, certain glycoproteins appear to be particularly affected. These include the lysosomal CBP1B serine carboxypeptidase, cell surface ESAG2 and the ESAG6 subunit of the essential parasite transferrin receptor (TfR). The pNAL deficient TfR in the mutants continued to function normally with respect to protein stability, transferrin binding, receptor mediated endocytosis of transferrin and subcellular localisation. Further the pNAL deficient mutants were as viable as wild type parasites in vitro and in in vivo mouse infection experiments. Although we were able to reproduce the inhibition of transferrin uptake with high concentrations of pNAL structural analogues (N-acetylchito-oligosaccharides), this effect disappeared at lower concentrations that still inhibited tomato lectin uptake, i.e., at concentrations able to outcompete lectin-pNAL binding. Based on these findings, we recommend revision of the pNAL-dependent receptor mediated endocytosis hypothesis.
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Affiliation(s)
- Samuel M. Duncan
- Wellcome Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Carla Gilabert Carbajo
- Faculty of Natural Sciences, Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Rupa Nagar
- Wellcome Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Qi Zhong
- Faculty of Natural Sciences, Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Conor Breen
- Regeneron Biotech, Raheen Business Park, Limerick, Ireland
| | - Michael A. J. Ferguson
- Wellcome Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Calvin Tiengwe
- Faculty of Natural Sciences, Department of Life Sciences, Imperial College London, London, United Kingdom
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3
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Trajano-Silva LAM, Mule SN, Palmisano G. Molecular tools to regulate gene expression in Trypanosoma cruzi. Adv Clin Chem 2024; 120:169-190. [PMID: 38762241 DOI: 10.1016/bs.acc.2024.04.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/20/2024]
Abstract
Developing molecular strategies to manipulate gene expression in trypanosomatids is challenging, particularly with respect to the unique gene expression mechanisms adopted by these unicellular parasites, such as polycistronic mRNA transcription and multi-gene families. In the case of Trypanosoma cruzi (T. cruzi), the causative agent of Chagas Disease, the lack of RNA interference machinery further complicated functional genetic studies important for understanding parasitic biology and developing biomarkers and potential therapeutic targets. Therefore, alternative methods of performing knockout and/or endogenous labelling experiments were developed to identify and understand the function of proteins for survival and interaction with the host. In this review, we present the main tools for the genetic manipulation of T. cruzi, focusing on the Clustered Regularly Interspaced Short Palindromic Repeats Cas9-associated system technique widely used in this organism. Moreover, we highlight the importance of using these tools to elucidate the function of uncharacterized and glycosylated proteins. Further developments of these technologies will allow the identification of new biomarkers, therapeutic targets and potential vaccines against Chagas disease with greater efficiency and speed.
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Affiliation(s)
- Lays Adrianne M Trajano-Silva
- Glycoproteomic Laboratory, Parasitology Department, Institute of Biomedical Science II, University of Sao Paulo, Sao Paulo, Brazil
| | - Simon Ngao Mule
- Glycoproteomic Laboratory, Parasitology Department, Institute of Biomedical Science II, University of Sao Paulo, Sao Paulo, Brazil
| | - Giuseppe Palmisano
- Glycoproteomic Laboratory, Parasitology Department, Institute of Biomedical Science II, University of Sao Paulo, Sao Paulo, Brazil; School of Natural Sciences, Macquarie University, Sydney, NSW, Australia.
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4
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Nakanishi M, Takezaki R, Takeguchi M, Hino M, Nomoto H. Synthetic arrest of Man 5GlcNAc 2-PP-Dol increases procyclin mRNA level and induces cell death in the bloodstream form Trypanosoma brucei brucei. Parasitol Int 2024; 99:102831. [PMID: 38048903 DOI: 10.1016/j.parint.2023.102831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 11/21/2023] [Accepted: 11/23/2023] [Indexed: 12/06/2023]
Abstract
The biosynthesis of N-linked glycan precursors in the endoplasmic reticulum is important for many eukaryotes. In particular, the synthesis of Man5GlcNAc2-PP-dolichol (M5-DLO) at the cytoplasmic face of the endoplasmic reticulum is essential for maintaining cellular functions. In Trypanosoma brucei, the unicellular organism that causes African trypanosomiasis, homologs of the mannosyltransferases ALG2 and ALG11, which are involved in the biosynthesis of M5-DLO, are found, but the effects of their deletion on cells remain unknown. In this study, we generated conditional gene knockout strains of TbALG2 and TbALG11 in the bloodstream form T. brucei. Decreased N-linked glycosylation and cell death were observed in both strains under non-permissive conditions, with TbALG2 having a greater effect than TbALG11. Transcriptomic analysis of cells losing expression of TbALG11 showed decrease in mRNAs for enzymes involved in glucose metabolism and increase in mRNAs for procyclins and variant surface glycoproteins. These results indicate that the M5-DLO biosynthetic pathway is essential for the proliferation of the bloodstream form T. brucei. They also suggest that the failure of this pathway induces the transcriptomic change.
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Affiliation(s)
- Masayuki Nakanishi
- Laboratory of Biochemistry, School of Pharmaceutical Sciences, Matsuyama University, Matsuyama, Ehime 790-8578, Japan.
| | - Reo Takezaki
- Laboratory of Biochemistry, School of Pharmaceutical Sciences, Matsuyama University, Matsuyama, Ehime 790-8578, Japan
| | - Masaki Takeguchi
- Laboratory of Biochemistry, School of Pharmaceutical Sciences, Matsuyama University, Matsuyama, Ehime 790-8578, Japan
| | - Mami Hino
- Laboratory of Biochemistry, School of Pharmaceutical Sciences, Matsuyama University, Matsuyama, Ehime 790-8578, Japan
| | - Hiroshi Nomoto
- Laboratory of Biochemistry, School of Pharmaceutical Sciences, Matsuyama University, Matsuyama, Ehime 790-8578, Japan
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5
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Senjor E, Pirro M, Švajger U, Prunk M, Sabotič J, Jewett A, Hensbergen PJ, Perišić Nanut M, Kos J. Different glycosylation profiles of cystatin F alter the cytotoxic potential of natural killer cells. Cell Mol Life Sci 2023; 81:8. [PMID: 38092995 PMCID: PMC10719177 DOI: 10.1007/s00018-023-05041-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 10/13/2023] [Accepted: 11/06/2023] [Indexed: 12/17/2023]
Abstract
Cystatin F, a cysteine peptidase inhibitor, is a potent modulator of NK cytotoxicity. By inhibiting granule-mediated cytotoxicity pathway, cystatin F induces formation of non-functional NK cell stage, called split-anergy. We show that N-glycosylation determines the localization and cellular function of cystatin F. Cystatin F mostly exhibited high-mannose glycosylation in U-937 cells, both high-mannose and complex glycosylation in NK-92 and primary NKs, and predominantly complex glycosylation in super-charged NKs. Manipulating N-glycosylation with kifunensine increased high-mannose glycosylation of cystatin F and lysosome localisation, which decreased cathepsin C activity and reduced NK cytotoxicity. Mannose-6-phosphate could significantly reduce the internalization of extracellular cystatin F. By comparing NK cells with different cytotoxic potentials, we found that high-mannose cystatin F was strongly associated with lysosomes and cathepsin C in NK-92 cell line. In contrast, in highly cytotoxic super-charged NKs, cystatin F with complex glycosylation was associated with the secretory pathway and less prone to inhibit cathepsin C. Modulating glycosylation to alter cystatin F localisation could increase the cytotoxicity of NK cells, thereby enhancing their therapeutic potential for treating cancer patients.
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Affiliation(s)
- Emanuela Senjor
- Department of Biotechnology, Jožef Stefan Institute, Ljubljana, Slovenia
- Faculty of Pharmacy, University of Ljubljana, Aškerčeva Cesta 7, 1000, Ljubljana, Slovenia
| | - Martina Pirro
- Center for Proteomics and Metabolomics, Leiden University Medical Center, Leiden, The Netherlands
| | - Urban Švajger
- Faculty of Pharmacy, University of Ljubljana, Aškerčeva Cesta 7, 1000, Ljubljana, Slovenia
- Blood Transfusion Centre of Slovenia, Ljubljana, Slovenia
| | - Mateja Prunk
- Department of Biotechnology, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Jerica Sabotič
- Department of Biotechnology, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Anahid Jewett
- Division of Oral Biology and Medicine, The Jane and Jerry Weintraub Center for Reconstructive Biotechnology, School of Dentistry, University of California Los Angeles, Los Angeles, USA
- The Jonsson Comprehensive Cancer Center, Los Angeles, USA
| | - Paul J Hensbergen
- Center for Proteomics and Metabolomics, Leiden University Medical Center, Leiden, The Netherlands
| | | | - Janko Kos
- Department of Biotechnology, Jožef Stefan Institute, Ljubljana, Slovenia.
- Faculty of Pharmacy, University of Ljubljana, Aškerčeva Cesta 7, 1000, Ljubljana, Slovenia.
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Ramírez AS, de Capitani M, Pesciullesi G, Kowal J, Bloch JS, Irobalieva RN, Reymond JL, Aebi M, Locher KP. Molecular basis for glycan recognition and reaction priming of eukaryotic oligosaccharyltransferase. Nat Commun 2022; 13:7296. [PMID: 36435935 PMCID: PMC9701220 DOI: 10.1038/s41467-022-35067-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 11/17/2022] [Indexed: 11/28/2022] Open
Abstract
Oligosaccharyltransferase (OST) is the central enzyme of N-linked protein glycosylation. It catalyzes the transfer of a pre-assembled glycan, GlcNAc2Man9Glc3, from a dolichyl-pyrophosphate donor to acceptor sites in secretory proteins in the lumen of the endoplasmic reticulum. Precise recognition of the fully assembled glycan by OST is essential for the subsequent quality control steps of glycoprotein biosynthesis. However, the molecular basis of the OST-donor glycan interaction is unknown. Here we present cryo-EM structures of S. cerevisiae OST in distinct functional states. Our findings reveal that the terminal glucoses (Glc3) of a chemo-enzymatically generated donor glycan analog bind to a pocket formed by the non-catalytic subunits WBP1 and OST2. We further find that binding either donor or acceptor substrate leads to distinct primed states of OST, where subsequent binding of the other substrate triggers conformational changes required for catalysis. This alternate priming allows OST to efficiently process closely spaced N-glycosylation sites.
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Affiliation(s)
- Ana S. Ramírez
- grid.5801.c0000 0001 2156 2780Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland
| | - Mario de Capitani
- grid.5734.50000 0001 0726 5157Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
| | - Giorgio Pesciullesi
- grid.5734.50000 0001 0726 5157Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
| | - Julia Kowal
- grid.5801.c0000 0001 2156 2780Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland
| | - Joël S. Bloch
- grid.5801.c0000 0001 2156 2780Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland
| | - Rossitza N. Irobalieva
- grid.5801.c0000 0001 2156 2780Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland
| | - Jean-Louis Reymond
- grid.5734.50000 0001 0726 5157Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
| | - Markus Aebi
- grid.5801.c0000 0001 2156 2780Institute of Microbiology, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland
| | - Kaspar P. Locher
- grid.5801.c0000 0001 2156 2780Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland
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7
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Common and unique features of glycosylation and glycosyltransferases in African trypanosomes. Biochem J 2022; 479:1743-1758. [PMID: 36066312 PMCID: PMC9472816 DOI: 10.1042/bcj20210778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 08/08/2022] [Accepted: 08/10/2022] [Indexed: 11/26/2022]
Abstract
Eukaryotic protein glycosylation is mediated by glycosyl- and oligosaccharyl-transferases. Here, we describe how African trypanosomes exhibit both evolutionary conservation and significant divergence compared with other eukaryotes in how they synthesise their glycoproteins. The kinetoplastid parasites have conserved components of the dolichol-cycle and oligosaccharyltransferases (OSTs) of protein N-glycosylation, and of glycosylphosphatidylinositol (GPI) anchor biosynthesis and transfer to protein. However, some components are missing, and they process and decorate their N-glycans and GPI anchors in unique ways. To do so, they appear to have evolved a distinct and functionally flexible glycosyltransferases (GT) family, the GT67 family, from an ancestral eukaryotic β3GT gene. The expansion and/or loss of GT67 genes appears to be dependent on parasite biology. Some appear to correlate with the obligate passage of parasites through an insect vector, suggesting they were acquired through GT67 gene expansion to assist insect vector (tsetse fly) colonisation. Others appear to have been lost in species that subsequently adopted contaminative transmission. We also highlight the recent discovery of a novel and essential GT11 family of kinetoplastid parasite fucosyltransferases that are uniquely localised to the mitochondria of Trypanosoma brucei and Leishmania major. The origins of these kinetoplastid FUT1 genes, and additional putative mitochondrial GT genes, are discussed.
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8
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Rosenau J, Grothaus IL, Yang Y, Kumar ND, Ciacchi LC, Kelm S, Waespy M. N-glycosylation modulates enzymatic activity of Trypanosoma congolense trans-sialidase. J Biol Chem 2022; 298:102403. [PMID: 35995210 PMCID: PMC9493392 DOI: 10.1016/j.jbc.2022.102403] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 08/15/2022] [Accepted: 08/16/2022] [Indexed: 11/24/2022] Open
Abstract
Trypanosomes cause the devastating disease trypanosomiasis, in which the action of trans-sialidase (TS) enzymes harbored on their surface is a key virulence factor. TS enzymes are N-glycosylated, but the biological functions of their glycans have remained elusive. In this study, we investigated the influence of N-glycans on the enzymatic activity and structural stability of TconTS1, a recombinant TS from the African parasite Trypanosoma congolense. We expressed the enzyme in Chinese hamster ovary Lec1 cells, which produce high-mannose type N-glycans similar to the TS N-glycosylation pattern in vivo. Our MALDI-TOF mass spectrometry data revealed that up to eight putative N-glycosylation sites were glycosylated. In addition, we determined that N-glycan removal via endoglycosidase Hf treatment of TconTS1 led to a decrease in substrate affinity relative to the untreated enzyme but had no impact on the conversion rate. Furthermore, we observed no changes in secondary structure elements of hypoglycosylated TconTS1 in CD experiments. Finally, our molecular dynamics simulations provided evidence for interactions between monosaccharide units of the highly flexible N-glycans and some conserved amino acids located at the catalytic site. These interactions led to conformational changes, possibly enhancing substrate accessibility and enzyme–substrate complex stability. The here-observed modulation of catalytic activity via N-glycans represents a so-far-unknown structure–function relationship potentially inherent in several members of the TS enzyme family.
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Affiliation(s)
- Jana Rosenau
- University of Bremen, Centre for Biomolecular Interactions Bremen, Faculty for Biology and Chemistry, 28359 Bremen, Germany
| | - Isabell Louise Grothaus
- University of Bremen, Centre for Biomolecular Interactions Bremen, Faculty for Biology and Chemistry, 28359 Bremen, Germany; University of Bremen, Hybrid Materials Interfaces Group, Faculty of Production Engineering, Bremen Center for Computational Materials Science, Center for Environmental Research and Sustainable Technology (UFT), and MAPEX Center for Materials and Processes, 28359 Bremen, Germany
| | - Yikun Yang
- University of Bremen, Centre for Biomolecular Interactions Bremen, Faculty for Biology and Chemistry, 28359 Bremen, Germany
| | - Nilima Dinesh Kumar
- University of Bremen, Centre for Biomolecular Interactions Bremen, Faculty for Biology and Chemistry, 28359 Bremen, Germany
| | - Lucio Colombi Ciacchi
- University of Bremen, Hybrid Materials Interfaces Group, Faculty of Production Engineering, Bremen Center for Computational Materials Science, Center for Environmental Research and Sustainable Technology (UFT), and MAPEX Center for Materials and Processes, 28359 Bremen, Germany
| | - Sørge Kelm
- University of Bremen, Centre for Biomolecular Interactions Bremen, Faculty for Biology and Chemistry, 28359 Bremen, Germany
| | - Mario Waespy
- University of Bremen, Centre for Biomolecular Interactions Bremen, Faculty for Biology and Chemistry, 28359 Bremen, Germany.
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9
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Duncan SM, Nagar R, Damerow M, Yashunsky DV, Buzzi B, Nikolaev AV, Ferguson MAJ. A Trypanosoma brucei β3 glycosyltransferase superfamily gene encodes a β1-6 GlcNAc-transferase mediating N-glycan and GPI anchor modification. J Biol Chem 2021; 297:101153. [PMID: 34478712 PMCID: PMC8477195 DOI: 10.1016/j.jbc.2021.101153] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 08/11/2021] [Accepted: 08/30/2021] [Indexed: 11/18/2022] Open
Abstract
The parasite Trypanosoma brucei exists in both a bloodstream form (BSF) and a procyclic form (PCF), which exhibit large carbohydrate extensions on the N-linked glycans and glycosylphosphatidylinositol (GPI) anchors, respectively. The parasite's glycoconjugate repertoire suggests at least 38 glycosyltransferase (GT) activities, 16 of which are currently uncharacterized. Here, we probe the function(s) of the uncharacterized GT67 glycosyltransferase family and a β3 glycosyltransferase (β3GT) superfamily gene, TbGT10. A BSF-null mutant, created by applying the diCre/loxP method in T. brucei for the first time, showed a fitness cost but was viable in vitro and in vivo and could differentiate into the PCF, demonstrating nonessentiality of TbGT10. The absence of TbGT10 impaired the elaboration of N-glycans and GPI anchor side chains in BSF and PCF parasites, respectively. Glycosylation defects included reduced BSF glycoprotein binding to the lectin ricin and monoclonal antibodies mAb139 and mAbCB1. The latter bind a carbohydrate epitope present on lysosomal glycoprotein p67 that we show here consists of (-6Galβ1-4GlcNAcβ1-)≥4 poly-N-acetyllactosamine repeats. Methylation linkage analysis of Pronase-digested glycopeptides isolated from BSF wild-type and TbGT10 null parasites showed a reduction in 6-O-substituted- and 3,6-di-O-substituted-Gal residues. These data define TbGT10 as a UDP-GlcNAc:βGal β1-6 GlcNAc-transferase. The dual role of TbGT10 in BSF N-glycan and PCF GPI-glycan elaboration is notable, and the β1-6 specificity of a β3GT superfamily gene product is unprecedented. The similar activities of trypanosome TbGT10 and higher-eukaryote I-branching enzyme (EC 2.4.1.150), which belong to glycosyltransferase families GT67 and GT14, respectively, in elaborating N-linked glycans, are a novel example of convergent evolution.
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Affiliation(s)
- Samuel M Duncan
- Wellcome Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Rupa Nagar
- Wellcome Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Manuela Damerow
- Wellcome Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Dmitry V Yashunsky
- Wellcome Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Benedetta Buzzi
- Wellcome Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Andrei V Nikolaev
- Wellcome Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Michael A J Ferguson
- Wellcome Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, United Kingdom.
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10
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Link F, Borges AR, Jones NG, Engstler M. To the Surface and Back: Exo- and Endocytic Pathways in Trypanosoma brucei. Front Cell Dev Biol 2021; 9:720521. [PMID: 34422837 PMCID: PMC8377397 DOI: 10.3389/fcell.2021.720521] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 07/06/2021] [Indexed: 01/10/2023] Open
Abstract
Trypanosoma brucei is one of only a few unicellular pathogens that thrives extracellularly in the vertebrate host. Consequently, the cell surface plays a critical role in both immune recognition and immune evasion. The variant surface glycoprotein (VSG) coats the entire surface of the parasite and acts as a flexible shield to protect invariant proteins against immune recognition. Antigenic variation of the VSG coat is the major virulence mechanism of trypanosomes. In addition, incessant motility of the parasite contributes to its immune evasion, as the resulting fluid flow on the cell surface drags immunocomplexes toward the flagellar pocket, where they are internalized. The flagellar pocket is the sole site of endo- and exocytosis in this organism. After internalization, VSG is rapidly recycled back to the surface, whereas host antibodies are thought to be transported to the lysosome for degradation. For this essential step to work, effective machineries for both sorting and recycling of VSGs must have evolved in trypanosomes. Our understanding of the mechanisms behind VSG recycling and VSG secretion, is by far not complete. This review provides an overview of the trypanosome secretory and endosomal pathways. Longstanding questions are pinpointed that, with the advent of novel technologies, might be answered in the near future.
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Affiliation(s)
- Fabian Link
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, Würzburg, Germany
| | - Alyssa R Borges
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, Würzburg, Germany
| | - Nicola G Jones
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, Würzburg, Germany
| | - Markus Engstler
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, Würzburg, Germany
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11
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Nihei CI, Nakanishi M. Cargo selection in the early secretory pathway of African trypanosomes. Parasitol Int 2021; 84:102379. [PMID: 34000424 DOI: 10.1016/j.parint.2021.102379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 03/30/2021] [Accepted: 05/06/2021] [Indexed: 11/25/2022]
Abstract
Membrane and secretory proteins are synthesized by ribosomes and then enter the endoplasmic reticulum (ER) where they undergo glycosylation and quality control for proper folding. Subsequently, proteins are transported to the Golgi apparatus and then sorted to the plasma membrane or intracellular organelles. Transport vesicles are formed at ER-exit sites (ERES) on the ER with several coat protein complexes. Cargo proteins loaded into the vesicles are selected by specific interactions with cargo receptors and/or adaptors during vesicle formation. p24 family and intracellular lectin ERGIC-53-membrane proteins are the known cargo receptors acting in the early secretory pathway (ER-Golgi). Oligomerization of the cargo receptors have been suggested to play an important role in cargo selection and sorting via posttranslational modifications in fungi and metazoans. On the other hand, the mechanisms involved in the early secretory pathway in protozoa remain unclear. In this review, we focus on Trypanosoma brucei as a representative of protozoan and discuss differences and commonalities in the molecular mechanisms of its early secretory pathway compared with other organisms.
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Affiliation(s)
- Coh-Ichi Nihei
- Institute of Microbial Chemistry, Microbial Chemistry Research Foundation (BIKAKEN), 3-14-23, Kamiosaki, Shinagawa-ku, Tokyo 141-0023, Japan.
| | - Masayuki Nakanishi
- Laboratory of Biochemistry, College of Pharmaceutical Sciences, Matsuyama University, Matsuyama, Ehime 790-8578, Japan.
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12
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Kightlinger W, Warfel KF, DeLisa MP, Jewett MC. Synthetic Glycobiology: Parts, Systems, and Applications. ACS Synth Biol 2020; 9:1534-1562. [PMID: 32526139 PMCID: PMC7372563 DOI: 10.1021/acssynbio.0c00210] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Indexed: 12/11/2022]
Abstract
Protein glycosylation, the attachment of sugars to amino acid side chains, can endow proteins with a wide variety of properties of great interest to the engineering biology community. However, natural glycosylation systems are limited in the diversity of glycoproteins they can synthesize, the scale at which they can be harnessed for biotechnology, and the homogeneity of glycoprotein structures they can produce. Here we provide an overview of the emerging field of synthetic glycobiology, the application of synthetic biology tools and design principles to better understand and engineer glycosylation. Specifically, we focus on how the biosynthetic and analytical tools of synthetic biology have been used to redesign glycosylation systems to obtain defined glycosylation structures on proteins for diverse applications in medicine, materials, and diagnostics. We review the key biological parts available to synthetic biologists interested in engineering glycoproteins to solve compelling problems in glycoscience, describe recent efforts to construct synthetic glycoprotein synthesis systems, and outline exemplary applications as well as new opportunities in this emerging space.
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Affiliation(s)
- Weston Kightlinger
- Department
of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Road, Tech E136, Evanston, Illinois 60208, United States
- Center
for Synthetic Biology, Northwestern University, 2145 Sheridan Road, Tech B486, Evanston, Illinois 60208, United States
| | - Katherine F. Warfel
- Department
of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Road, Tech E136, Evanston, Illinois 60208, United States
- Center
for Synthetic Biology, Northwestern University, 2145 Sheridan Road, Tech B486, Evanston, Illinois 60208, United States
| | - Matthew P. DeLisa
- Department
of Microbiology, Cornell University, 123 Wing Drive, Ithaca, New York 14853, United States
- Robert
Frederick Smith School of Chemical and Biomolecular Engineering, Cornell University, 120 Olin Hall, Ithaca, New York 14853, United States
- Nancy
E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Weill Hall, Ithaca, New York 14853, United States
| | - Michael C. Jewett
- Department
of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Road, Tech E136, Evanston, Illinois 60208, United States
- Center
for Synthetic Biology, Northwestern University, 2145 Sheridan Road, Tech B486, Evanston, Illinois 60208, United States
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13
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Niu G, Shao Z, Liu C, Chen T, Jiao Q, Hong Z. Comparative and evolutionary analyses of the divergence of plant oligosaccharyltransferase STT3 isoforms. FEBS Open Bio 2020; 10:468-483. [PMID: 32011067 PMCID: PMC7050244 DOI: 10.1002/2211-5463.12804] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 01/11/2020] [Accepted: 01/30/2020] [Indexed: 11/08/2022] Open
Abstract
STT3 is a catalytic subunit of hetero-oligomeric oligosaccharyltransferase (OST), which is important for asparagine-linked glycosylation. In mammals and plants, OSTs with different STT3 isoforms exhibit distinct levels of enzymatic efficiency or different responses to stressors. Although two different STT3 isoforms have been identified in both plants and animals, it remains unclear whether these isoforms result from gene duplication in an ancestral eukaryote. Furthermore, the molecular mechanisms underlying the functional divergences between the two STT3 isoforms in plant have not been well elucidated. Here, we conducted phylogenetic analysis of the major evolutionary node species and suggested that gene duplications of STT3 may have occurred independently in animals and plants. Across land plants, the exon-intron structure differed between the two STT3 isoforms, but was highly conserved for each isoform. Most angiosperm STT3a genes had 23 exons with intron phase 0, while STT3b genes had 6 exons with intron phase 2. Characteristic motifs (motif 18 and 19) of STT3s were mapped to different structure domains in the plant STT3 proteins. These two motifs overlap with regions of high nonsynonymous-to-synonymous substitution rates, suggesting the regions may be related to functional difference between STT3a and STT3b. In addition, promoter elements and gene expression profiles were different between the two isoforms, indicating expression pattern divergence of the two genes. Collectively, the identified differences may result in the functional divergence of plant STT3s.
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Affiliation(s)
- Guanting Niu
- State Key Laboratory of Pharmaceutical Biotechnology, NJU Advanced Institute for Life Sciences (NAILS), School of Life Sciences, Nanjing University, China
| | - Zhuqing Shao
- State Key Laboratory of Pharmaceutical Biotechnology, NJU Advanced Institute for Life Sciences (NAILS), School of Life Sciences, Nanjing University, China
| | - Chuanfa Liu
- Department of Biology, Institute of Plant and Food Science, Southern University of Science and Technology, Shenzhen, China
| | - Tianshu Chen
- State Key Laboratory of Pharmaceutical Biotechnology, NJU Advanced Institute for Life Sciences (NAILS), School of Life Sciences, Nanjing University, China
| | - Qingsong Jiao
- State Key Laboratory of Pharmaceutical Biotechnology, NJU Advanced Institute for Life Sciences (NAILS), School of Life Sciences, Nanjing University, China
| | - Zhi Hong
- State Key Laboratory of Pharmaceutical Biotechnology, NJU Advanced Institute for Life Sciences (NAILS), School of Life Sciences, Nanjing University, China
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14
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Koeller CM, Tiengwe C, Schwartz KJ, Bangs JD. Steric constraints control processing of glycosylphosphatidylinositol anchors in Trypanosoma brucei. J Biol Chem 2020; 295:2227-2238. [PMID: 31932305 DOI: 10.1074/jbc.ra119.010847] [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: 08/28/2019] [Revised: 12/26/2019] [Indexed: 11/06/2022] Open
Abstract
The transferrin receptor (TfR) of the bloodstream form (BSF) of Trypanosoma brucei is a heterodimer comprising glycosylphosphatidylinositol (GPI)-anchored expression site-associated gene 6 (ESAG6 or E6) and soluble ESAG7. Mature E6 has five N-glycans, consisting of three oligomannose and two unprocessed paucimannose structures. Its GPI anchor is modified by the addition of 4-6 α-galactose residues. TfR binds tomato lectin (TL), specific for N-acetyllactosamine (LacNAc) repeats, and previous studies have shown transport-dependent increases in E6 size consistent with post-glycan processing in the endoplasmic reticulum. Using pulse-chase radiolabeling, peptide-N-glycosidase F treatment, lectin pulldowns, and exoglycosidase treatment, we have now investigated TfR N-glycan and GPI processing. E6 increased ∼5 kDa during maturation, becoming reactive with both TL and Erythrina cristagalli lectin (ECL, terminal LacNAc), indicating synthesis of poly-LacNAc on paucimannose N-glycans. This processing was lost after exoglycosidase treatment and after RNAi-based silencing of TbSTT3A, the oligosaccharyltransferase that transfers paucimannose structures to nascent secretory polypeptides. These results contradict previous structural studies. Minor GPI processing was also observed, consistent with α-galactose addition. However, increasing the spacing between E6 protein and the GPI ω-site (aa 4-7) resulted in extensive post-translational processing of the GPI anchor to a form that was TL/ECL-reactive, suggesting the addition of LacNAc structures, confirmed by identical assays with BiPNHP, a non-N-glycosylated GPI-anchored reporter. We conclude that BSF trypanosomes can modify GPIs by generating structures reminiscent of those present in insect-stage trypanosomes and that steric constraints, not stage-specific expression of glycosyltransferases, regulate GPI processing.
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Affiliation(s)
- Carolina M Koeller
- Department of Microbiology and Immunology, School of Medicine and Biomedical Sciences, University at Buffalo (SUNY), Buffalo, New York 14214
| | - Calvin Tiengwe
- Department of Microbiology and Immunology, School of Medicine and Biomedical Sciences, University at Buffalo (SUNY), Buffalo, New York 14214
| | - Kevin J Schwartz
- Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, Wisconsin, 53706
| | - James D Bangs
- Department of Microbiology and Immunology, School of Medicine and Biomedical Sciences, University at Buffalo (SUNY), Buffalo, New York 14214.
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15
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Tjondro HC, Loke I, Chatterjee S, Thaysen-Andersen M. Human protein paucimannosylation: cues from the eukaryotic kingdoms. Biol Rev Camb Philos Soc 2019; 94:2068-2100. [PMID: 31410980 DOI: 10.1111/brv.12548] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 07/10/2019] [Accepted: 07/17/2019] [Indexed: 12/11/2022]
Abstract
Paucimannosidic proteins (PMPs) are bioactive glycoproteins carrying truncated α- or β-mannosyl-terminating asparagine (N)-linked glycans widely reported across the eukaryotic domain. Our understanding of human PMPs remains limited, despite findings documenting their existence and association with human disease glycobiology. This review comprehensively surveys the structures, biosynthetic routes and functions of PMPs across the eukaryotic kingdoms with the aim of synthesising an improved understanding on the role of protein paucimannosylation in human health and diseases. Convincing biochemical, glycoanalytical and biological data detail a vast structural heterogeneity and fascinating tissue- and subcellular-specific expression of PMPs within invertebrates and plants, often comprising multi-α1,3/6-fucosylation and β1,2-xylosylation amongst other glycan modifications and non-glycan substitutions e.g. O-methylation. Vertebrates and protists express less-heterogeneous PMPs typically only comprising variable core fucosylation of bi- and trimannosylchitobiose core glycans. In particular, the Manα1,6Manβ1,4GlcNAc(α1,6Fuc)β1,4GlcNAcβAsn glycan (M2F) decorates various human neutrophil proteins reportedly displaying bioactivity and structural integrity demonstrating that they are not degradation products. Less-truncated paucimannosidic glycans (e.g. M3F) are characteristic glycosylation features of proteins expressed by human cancer and stem cells. Concertedly, these observations suggest the involvement of human PMPs in processes related to innate immunity, tumorigenesis and cellular differentiation. The absence of human PMPs in diverse bodily fluids studied under many (patho)physiological conditions suggests extravascular residence and points to localised functions of PMPs in peripheral tissues. Absence of PMPs in Fungi indicates that paucimannosylation is common, but not universally conserved, in eukaryotes. Relative to human PMPs, the expression of PMPs in plants, invertebrates and protists is more tissue-wide and constitutive yet, similar to their human counterparts, PMP expression remains regulated by the physiology of the producing organism and PMPs evidently serve essential functions in development, cell-cell communication and host-pathogen/symbiont interactions. In most PMP-producing organisms, including humans, the N-acetyl-β-hexosaminidase isoenzymes and linkage-specific α-mannosidases are glycoside hydrolases critical for generating PMPs via N-acetylglucosaminyltransferase I (GnT-I)-dependent and GnT-I-independent truncation pathways. However, the identity and structure of many species-specific PMPs in eukaryotes, their biosynthetic routes, strong tissue- and development-specific expression, and diverse functions are still elusive. Deep exploration of these PMP features involving, for example, the characterisation of endogenous PMP-recognising lectins across a variety of healthy and N-acetyl-β-hexosaminidase-deficient human tissue types and identification of microbial adhesins reactive to human PMPs, are amongst the many tasks required for enhanced insight into the glycobiology of human PMPs. In conclusion, the literature supports the notion that PMPs are significant, yet still heavily under-studied biomolecules in human glycobiology that serve essential functions and create structural heterogeneity not dissimilar to other human N-glycoprotein types. Human PMPs should therefore be recognised as bioactive glycoproteins that are distinctly different from the canonical N-glycoprotein classes and which warrant a more dedicated focus in glycobiological research.
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Affiliation(s)
- Harry C Tjondro
- Department of Molecular Sciences, Macquarie University, Sydney, New South Wales, 2109, Australia
| | - Ian Loke
- Department of Molecular Sciences, Macquarie University, Sydney, New South Wales, 2109, Australia.,Department of Biological Sciences, National University of Singapore, Singapore 117543, Singapore
| | - Sayantani Chatterjee
- Department of Molecular Sciences, Macquarie University, Sydney, New South Wales, 2109, Australia
| | - Morten Thaysen-Andersen
- Department of Molecular Sciences, Macquarie University, Sydney, New South Wales, 2109, Australia
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16
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Jervis AJ, Wood AG, Cain JA, Butler JA, Frost H, Lord E, Langdon R, Cordwell SJ, Wren BW, Linton D. Functional analysis of the Helicobacter pullorum N-linked protein glycosylation system. Glycobiology 2018; 28:233-244. [PMID: 29340583 PMCID: PMC6025236 DOI: 10.1093/glycob/cwx110] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 01/10/2018] [Indexed: 11/23/2022] Open
Abstract
N-linked protein glycosylation systems operate in species from all three domains of life. The model bacterial N-linked glycosylation system from Campylobacter jejuni is encoded by pgl genes present at a single chromosomal locus. This gene cluster includes the pglB oligosaccharyltransferase responsible for transfer of glycan from lipid carrier to protein. Although all genomes from species of the Campylobacter genus contain a pgl locus, among the related Helicobacter genus only three evolutionarily related species (H. pullorum, H. canadensis and H. winghamensis) potentially encode N-linked protein glycosylation systems. Helicobacter putative pgl genes are scattered in five chromosomal loci and include two putative oligosaccharyltransferase-encoding pglB genes per genome. We have previously demonstrated the in vitro N-linked glycosylation activity of H. pullorum resulting in transfer of a pentasaccharide to a peptide at asparagine within the sequon (D/E)XNXS/T. In this study, we identified the first H. pullorum N-linked glycoprotein, termed HgpA. Production of histidine-tagged HgpA in the background of insertional knockout mutants of H. pullorum pgl/wbp genes followed by analysis of HgpA glycan structures demonstrated the role of individual gene products in the PglB1-dependent N-linked protein glycosylation pathway. Glycopeptide purification by zwitterionic-hydrophilic interaction liquid chromatography coupled with tandem mass spectrometry identified six glycosites from five H. pullorum proteins, which was consistent with proteins reactive with a polyclonal antiserum generated against glycosylated HgpA. This study demonstrates functioning of a H. pullorum N-linked general protein glycosylation system.
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Affiliation(s)
- Adrian J Jervis
- Manchester Institute of Biotechnology, SYNBIOCHEM, University of Manchester, Manchester, UK
| | - Alison G Wood
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK
| | - Joel A Cain
- School of Molecular Bioscience and Charles Perkins Centre, The University of Sydney, 2006Australia
| | - Jonathan A Butler
- School of Healthcare Science, Manchester Metropolitan University, Manchester M1 5GD, UK
| | - Helen Frost
- Faculty of Biology, Medicine and Health, Michael Smith Building, University of Manchester, Manchester M13 9PT, UK
| | - Elizabeth Lord
- Faculty of Biology, Medicine and Health, Michael Smith Building, University of Manchester, Manchester M13 9PT, UK
| | - Rebecca Langdon
- Pathogen Molecular Biology Unit, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK
| | - Stuart J Cordwell
- School of Molecular Bioscience and Charles Perkins Centre, The University of Sydney, 2006Australia
| | - Brendan W Wren
- Pathogen Molecular Biology Unit, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK
| | - Dennis Linton
- Faculty of Biology, Medicine and Health, Michael Smith Building, University of Manchester, Manchester M13 9PT, UK
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17
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Tiengwe C, Koeller CM, Bangs JD. Endoplasmic reticulum-associated degradation and disposal of misfolded GPI-anchored proteins in Trypanosoma brucei. Mol Biol Cell 2018; 29:2397-2409. [PMID: 30091673 PMCID: PMC6233060 DOI: 10.1091/mbc.e18-06-0380] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Misfolded secretory proteins are retained by endoplasmic reticulum quality control (ERQC) and degraded in the proteasome by ER-associated degradation (ERAD). However, in yeast and mammals, misfolded glycosylphosphatidylinositol (GPI)-anchored proteins are preferentially degraded in the vacuole/lysosome. We investigate this process in the divergent eukaryotic pathogen Trypanosoma brucei using a misfolded GPI-anchored subunit (HA:E6) of the trypanosome transferrin receptor. HA:E6 is N-glycosylated and GPI-anchored and accumulates in the ER as aggregates. Treatment with MG132, a proteasome inhibitor, generates a smaller protected polypeptide (HA:E6*), consistent with turnover in the proteasome. HA:E6* partitions between membrane and cytosol fractions, and both pools are proteinase K-sensitive, indicating cytosolic disposition of membrane-associated HA:E6*. HA:E6* is de-N-glycosylated and has a full GPI-glycan structure from which dimyristoylglycerol has been removed, indicating that complete GPI removal is not a prerequisite for proteasomal degradation. However, HA:E6* is apparently not ubiquitin-modified. The trypanosome GPI anchor is a forward trafficking signal; thus the dynamic tension between ERQC and ER exit favors degradation by ERAD. These results differ markedly from the standard eukaryotic model systems and may indicate an evolutionary advantage related to pathogenesis.
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Affiliation(s)
- Calvin Tiengwe
- Department of Microbiology and Immunology, School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY 14214
| | - Carolina M Koeller
- Department of Microbiology and Immunology, School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY 14214
| | - James D Bangs
- Department of Microbiology and Immunology, School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY 14214
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18
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Kelner A, Tinti M, Guther MLS, Foth BJ, Chappell L, Berriman M, Cowling VH, Ferguson MAJ. The mRNA cap methyltransferase gene TbCMT1 is not essential in vitro but is a virulence factor in vivo for bloodstream form Trypanosoma brucei. PLoS One 2018; 13:e0201263. [PMID: 30040830 PMCID: PMC6057678 DOI: 10.1371/journal.pone.0201263] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 07/11/2018] [Indexed: 01/16/2023] Open
Abstract
Messenger RNA is modified by the addition of a 5' methylated cap structure, which protects the transcript and recruits protein complexes that mediate RNA processing and/or the initiation of translation. Two genes encoding mRNA cap methyltransferases have been identified in T. brucei: TbCMT1 and TbCGM1. Here we analysed the impact of TbCMT1 gene deletion on bloodstream form T. brucei cells. TbCMT1 was dispensable for parasite proliferation in in vitro culture. However, significantly decreased parasitemia was observed in mice inoculated with TbCMT1 null and conditional null cell lines. Using RNA-Seq, we observed that several cysteine peptidase mRNAs were downregulated in TbCMT1 null cells lines. The cysteine peptidase Cathepsin-L was also shown to be reduced at the protein level in TbCMT1 null cell lines. Our data suggest that TbCMT1 is not essential to bloodstream form T. brucei growth in vitro or in vivo but that it contributes significantly to parasite virulence in vivo.
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Affiliation(s)
- Anna Kelner
- Wellcome Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Michele Tinti
- Wellcome Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Maria Lucia S. Guther
- Wellcome Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | | | - Lia Chappell
- The Wellcome Trust Sanger Institute, Hinxton, United Kingdom
| | | | - Victoria Haigh Cowling
- Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Michael A. J. Ferguson
- Wellcome Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, United Kingdom
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19
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Ramírez AS, Boilevin J, Biswas R, Gan BH, Janser D, Aebi M, Darbre T, Reymond JL, Locher KP. Characterization of the single-subunit oligosaccharyltransferase STT3A from Trypanosoma brucei using synthetic peptides and lipid-linked oligosaccharide analogs. Glycobiology 2018; 27:525-535. [PMID: 28204532 PMCID: PMC5421464 DOI: 10.1093/glycob/cwx017] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Accepted: 02/10/2017] [Indexed: 01/11/2023] Open
Abstract
The initial transfer of a complex glycan in protein N-glycosylation is catalyzed by oligosaccharyltransferase (OST), which is generally a multisubunit membrane protein complex in the endoplasmic reticulum but a single-subunit enzyme (ssOST) in some protists. To investigate the reaction mechanism of ssOST, we recombinantly expressed, purified and characterized the STT3A protein from Trypanosoma brucei (TbSTT3A). We analyzed the in vitro activity of TbSTT3A by synthesizing fluorescently labeled acceptor peptides as well as lipid-linked oligosaccharide (LLO) analogs containing a chitobiose moiety coupled to oligoprenyl carriers of distinct lengths (C10, C15, C20 and C25) and with different double bond stereochemistry. We found that in addition to proline, charged residues at the +1 position of the sequon inhibited glycan transfer. An acidic residue at the −2 position significantly increased catalytic turnover but was not essential, in contrast to the bacterial OST. While all synthetic LLO analogs were processed by TbSTT3A, the length of the polyprenyl tail, but not the stereochemistry of the double bonds, determined their apparent affinity. We also synthesized phosphonate analogs of the LLOs, which were found to be competitive inhibitors of the reaction, although with lower apparent affinity to TbSTT3A than the active pyrophosphate analogs.
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Affiliation(s)
- Ana S Ramírez
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), CH-8093 Zürich, Switzerland
| | - Jérémy Boilevin
- Department of Chemistry and Biochemistry, University of Berne, CH-3012 Berne, Switzerland
| | - Rasomoy Biswas
- Department of Chemistry and Biochemistry, University of Berne, CH-3012 Berne, Switzerland
| | - Bee Ha Gan
- Department of Chemistry and Biochemistry, University of Berne, CH-3012 Berne, Switzerland
| | - Daniel Janser
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), CH-8093 Zürich, Switzerland
| | - Markus Aebi
- Institute of Microbiology, Eidgenössische Technische Hochschule (ETH), CH-8093 Zürich, Switzerland
| | - Tamis Darbre
- Department of Chemistry and Biochemistry, University of Berne, CH-3012 Berne, Switzerland
| | - Jean-Louis Reymond
- Department of Chemistry and Biochemistry, University of Berne, CH-3012 Berne, Switzerland
| | - Kaspar P Locher
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), CH-8093 Zürich, Switzerland
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20
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Cova M, López-Gutiérrez B, Artigas-Jerónimo S, González-Díaz A, Bandini G, Maere S, Carretero-Paulet L, Izquierdo L. The Apicomplexa-specific glucosamine-6-phosphate N-acetyltransferase gene family encodes a key enzyme for glycoconjugate synthesis with potential as therapeutic target. Sci Rep 2018; 8:4005. [PMID: 29507322 PMCID: PMC5838249 DOI: 10.1038/s41598-018-22441-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Accepted: 02/22/2018] [Indexed: 02/06/2023] Open
Abstract
Apicomplexa form a phylum of obligate parasitic protozoa of great clinical and veterinary importance. These parasites synthesize glycoconjugates for their survival and infectivity, but the enzymatic steps required to generate the glycosylation precursors are not completely characterized. In particular, glucosamine-phosphate N-acetyltransferase (GNA1) activity, needed to produce the essential UDP-N-acetylglucosamine (UDP-GlcNAc) donor, has not been identified in any Apicomplexa. We scanned the genomes of Plasmodium falciparum and representatives from six additional main lineages of the phylum for proteins containing the Gcn5-related N-acetyltransferase (GNAT) domain. One family of GNAT-domain containing proteins, composed by a P. falciparum sequence and its six apicomplexan orthologs, rescued the growth of a yeast temperature-sensitive GNA1 mutant. Heterologous expression and in vitro assays confirmed the GNA1 enzymatic activity in all lineages. Sequence, phylogenetic and synteny analyses suggest an independent origin of the Apicomplexa-specific GNA1 family, parallel to the evolution of a different GNA1 family in other eukaryotes. The inability to disrupt an otherwise modifiable gene target suggests that the enzyme is essential for P. falciparum growth. The relevance of UDP-GlcNAc for parasite viability, together with the independent evolution and unique sequence features of Apicomplexa GNA1, highlights the potential of this enzyme as a selective therapeutic target against apicomplexans.
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Affiliation(s)
- Marta Cova
- ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic - Universitat de Barcelona, Barcelona, Spain
| | - Borja López-Gutiérrez
- ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic - Universitat de Barcelona, Barcelona, Spain
| | - Sara Artigas-Jerónimo
- ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic - Universitat de Barcelona, Barcelona, Spain
| | - Aida González-Díaz
- ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic - Universitat de Barcelona, Barcelona, Spain
| | - Giulia Bandini
- Department of Molecular and Cell Biology, Boston University Goldman School of Dental Medicine, Boston, USA
| | - Steven Maere
- Ghent University, Department of Plant Biotechnology and Bioinformatics, B-9052, Ghent, Belgium
- VIB Center for Plant Systems Biology, B-9052, Ghent, Belgium
- Bioinformatics Institute Ghent, Ghent University, B-9052, Ghent, Belgium
| | - Lorenzo Carretero-Paulet
- Ghent University, Department of Plant Biotechnology and Bioinformatics, B-9052, Ghent, Belgium.
- VIB Center for Plant Systems Biology, B-9052, Ghent, Belgium.
- Bioinformatics Institute Ghent, Ghent University, B-9052, Ghent, Belgium.
| | - Luis Izquierdo
- ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic - Universitat de Barcelona, Barcelona, Spain.
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21
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Kohda D. Structural Basis of Protein Asn-Glycosylation by Oligosaccharyltransferases. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1104:171-199. [PMID: 30484249 DOI: 10.1007/978-981-13-2158-0_9] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Glycosylation of asparagine residues is a ubiquitous protein modification. This N-glycosylation is essential in Eukaryotes, but principally nonessential in Prokaryotes (Archaea and Eubacteria), although it facilitates their survival and pathogenicity. In many reviews, Archaea have received far less attention than Eubacteria, but this review will cover the N-glycosylation in the three domains of life. The oligosaccharide chain is preassembled on a lipid-phospho carrier to form a donor substrate, lipid-linked oligosaccharide (LLO). The en bloc transfer of an oligosaccharide from LLO to selected Asn residues in the Asn-X-Ser/Thr (X≠Pro) sequons in a polypeptide chain is catalyzed by a membrane-bound enzyme, oligosaccharyltransferase (OST). Over the last 10 years, the three-dimensional structures of the catalytic subunits of the Stt3/AglB/PglB proteins, with an acceptor peptide and a donor LLO, have been determined by X-ray crystallography, and recently the complex structures with other subunits have been determined by cryo-electron microscopy . Structural comparisons within the same species and across the different domains of life yielded a unified view of the structures and functions of OSTs. A catalytic structure in the TM region accounts for the amide bond twisting, which increases the reactivity of the side-chain nitrogen atom of the acceptor Asn residue in the sequon. The Ser/Thr-binding pocket in the C-terminal domain explains the requirement for hydroxy amino acid residues in the sequon. As expected, the two functional structures are formed by the involvement of short amino acid motifs conserved across the three domains of life.
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Affiliation(s)
- Daisuke Kohda
- Division of Structural Biology, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan.
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Kitajima T, Xue W, Liu YS, Wang CD, Liu SS, Fujita M, Gao XD. Construction of green fluorescence protein mutant to monitor STT3B-dependent N-glycosylation. FEBS J 2017; 285:915-928. [PMID: 29282902 DOI: 10.1111/febs.14375] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Revised: 11/06/2017] [Accepted: 12/21/2017] [Indexed: 12/21/2022]
Abstract
Oligosaccharyltransferases (OSTs) mediate the en bloc transfer of N-glycan intermediates onto the asparagine residue in glycosylation sequons (N-X-S/T, X≠P). These enzymes are typically heteromeric complexes composed of several membrane-associated subunits, in which STT3 is highly conserved as a catalytic core. Metazoan organisms encode two STT3 genes (STT3A and STT3B) in their genome, resulting in the formation of at least two distinct OST isoforms consisting of shared subunits and complex specific subunits. The STT3A isoform of OST primarily glycosylates substrate polypeptides cotranslationally, whereas the STT3B isoform is involved in cotranslational and post-translocational glycosylation of sequons that are skipped by the STT3A isoform. Here, we describe mutant constructs of monomeric enhanced green fluorescent protein (mEGFP), which are susceptible to STT3B-dependent N-glycosylation. The endoplasmic reticulum-localized mEGFP (ER-mEGFP) mutants contained an N-glycosylation sequon at their C-terminus and exhibited increased fluorescence in response to N-glycosylation. Isoform-specific glycosylation of the constructs was confirmed by using STT3A- or STT3B-knockout cell lines. Among the mutant constructs that we tested, the ER-mEGFP mutant containing the N185 -C186 -T187 sequon was the best substrate for the STT3B isoform in terms of glycosylation efficiency and fluorescence change. Our results suggest that the mutant ER-mEGFP is useful for monitoring STT3B-dependent post-translocational N-glycosylation in cells of interest, such as those from putative patients with a congenital disorder of glycosylation.
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Affiliation(s)
- Toshihiko Kitajima
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Wei Xue
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Yi-Shi Liu
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Chun-Di Wang
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Si-Si Liu
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Morihisa Fujita
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Xiao-Dong Gao
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
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23
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Exploring the Glycans of Euglena gracilis. BIOLOGY 2017; 6:biology6040045. [PMID: 29244725 PMCID: PMC5745450 DOI: 10.3390/biology6040045] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 12/05/2017] [Accepted: 12/08/2017] [Indexed: 12/13/2022]
Abstract
Euglena gracilis is an alga of great biotechnological interest and extensive metabolic capacity, able to make high levels of bioactive compounds, such as polyunsaturated fatty acids, vitamins and β-glucan. Previous work has shown that Euglena expresses a wide range of carbohydrate-active enzymes, suggesting an unexpectedly high capacity for the synthesis of complex carbohydrates for a single-celled organism. Here, we present an analysis of some of the carbohydrates synthesised by Euglena gracilis. Analysis of the sugar nucleotide pool showed that there are the substrates necessary for synthesis of complex polysaccharides, including the unusual sugar galactofuranose. Lectin- and antibody-based profiling of whole cells and extracted carbohydrates revealed a complex galactan, xylan and aminosugar based surface. Protein N-glycan profiling, however, indicated that just simple high mannose-type glycans are present and that they are partially modified with putative aminoethylphosphonate moieties. Together, these data indicate that Euglena possesses a complex glycan surface, unrelated to plant cell walls, while its protein glycosylation is simple. Taken together, these findings suggest that Euglena gracilis may lend itself to the production of pharmaceutical glycoproteins.
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Jinnelov A, Ali L, Tinti M, Güther MLS, Ferguson MAJ. Single-subunit oligosaccharyltransferases of Trypanosoma brucei display different and predictable peptide acceptor specificities. J Biol Chem 2017; 292:20328-20341. [PMID: 28928222 PMCID: PMC5724017 DOI: 10.1074/jbc.m117.810945] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 09/13/2017] [Indexed: 11/10/2022] Open
Abstract
Trypanosoma brucei causes African trypanosomiasis and contains three full-length oligosaccharyltransferase (OST) genes; two of which, TbSTT3A and TbSTT3B, are expressed in the bloodstream form of the parasite. These OSTs have different peptide acceptor and lipid-linked oligosaccharide donor specificities, and trypanosomes do not follow many of the canonical rules developed for other eukaryotic N-glycosylation pathways, raising questions as to the basic architecture and detailed function of trypanosome OSTs. Here, we show by blue-native gel electrophoresis and stable isotope labeling in cell culture proteomics that the TbSTT3A and TbSTT3B proteins associate with each other in large complexes that contain no other detectable protein subunits. We probed the peptide acceptor specificities of the OSTs in vivo using a transgenic glycoprotein reporter system and performed glycoproteomics on endogenous parasite glycoproteins using sequential endoglycosidase H and peptide:N-glycosidase-F digestions. This allowed us to assess the relative occupancies of numerous N-glycosylation sites by endoglycosidase H-resistant N-glycans originating from Man5GlcNAc2-PP-dolichol transferred by TbSTT3A, and endoglycosidase H-sensitive N-glycans originating from Man9GlcNAc2-PP-dolichol transferred by TbSTT3B. Using machine learning, we assessed the features that best define TbSTT3A and TbSTT3B substrates in vivo and built an algorithm to predict the types of N-glycan most likely to predominate at all the putative N-glycosylation sites in the parasite proteome. Finally, molecular modeling was used to suggest why TbSTT3A has a distinct preference for sequons containing and/or flanked by acidic amino acid residues. Together, these studies provide insights into how a highly divergent eukaryote has re-wired protein N-glycosylation to provide protein sequence-specific N-glycan modifications. Data are available via ProteomeXchange with identifiers PXD007236, PXD007267, and PXD007268.
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Affiliation(s)
- Anders Jinnelov
- Wellcome Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom
| | - Liaqat Ali
- Wellcome Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom
| | - Michele Tinti
- Wellcome Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom
| | - Maria Lucia S Güther
- Wellcome Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom
| | - Michael A J Ferguson
- Wellcome Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom.
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25
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Poljak K, Breitling J, Gauss R, Rugarabamu G, Pellanda M, Aebi M. Analysis of substrate specificity of Trypanosoma brucei oligosaccharyltransferases (OSTs) by functional expression of domain-swapped chimeras in yeast. J Biol Chem 2017; 292:20342-20352. [PMID: 29042445 DOI: 10.1074/jbc.m117.811133] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 10/11/2017] [Indexed: 11/06/2022] Open
Abstract
N-Linked protein glycosylation is an essential and highly conserved post-translational modification in eukaryotes. The transfer of a glycan from a lipid-linked oligosaccharide (LLO) donor to the asparagine residue of a nascent polypeptide chain is catalyzed by an oligosaccharyltransferase (OST) in the lumen of the endoplasmic reticulum (ER). Trypanosoma brucei encodes three paralogue single-protein OSTs called TbSTT3A, TbSTT3B, and TbSTT3C that can functionally complement the Saccharomyces cerevisiae OST, making it an ideal experimental system to study the fundamental properties of OST activity. We characterized the LLO and polypeptide specificity of all three TbOST isoforms and their chimeric forms in the heterologous expression host S. cerevisiae where we were able to apply yeast genetic tools and newly developed glycoproteomics methods. We demonstrated that TbSTT3A accepted LLO substrates ranging from Man5GlcNAc2 to Man7GlcNAc2 In contrast, TbSTT3B required more complex precursors ranging from Man6GlcNAc2 to Glc3Man9GlcNAc2 structures, and TbSTT3C did not display any LLO preference. Sequence differences between the isoforms cluster in three distinct regions. We have swapped the individual regions between different OST proteins and identified region 2 to influence the specificity toward the LLO and region 1 to influence polypeptide substrate specificity. These results provide a basis to further investigate the molecular mechanisms and contribution of single amino acids in OST interaction with its substrates.
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Affiliation(s)
- Kristina Poljak
- Institute of Microbiology, ETH Zurich, Vladimir-Prelog-Weg 4, CH-8093 Zurich, Switzerland
| | - Jörg Breitling
- Institute of Microbiology, ETH Zurich, Vladimir-Prelog-Weg 4, CH-8093 Zurich, Switzerland
| | - Robert Gauss
- Institute of Microbiology, ETH Zurich, Vladimir-Prelog-Weg 4, CH-8093 Zurich, Switzerland
| | - George Rugarabamu
- Institute of Microbiology, ETH Zurich, Vladimir-Prelog-Weg 4, CH-8093 Zurich, Switzerland
| | - Mauro Pellanda
- Institute of Microbiology, ETH Zurich, Vladimir-Prelog-Weg 4, CH-8093 Zurich, Switzerland
| | - Markus Aebi
- Institute of Microbiology, ETH Zurich, Vladimir-Prelog-Weg 4, CH-8093 Zurich, Switzerland.
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26
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Castillo-Acosta VM, Balzarini J, González-Pacanowska D. Surface Glycans: A Therapeutic Opportunity for Kinetoplastid Diseases. Trends Parasitol 2017; 33:775-787. [PMID: 28760415 DOI: 10.1016/j.pt.2017.06.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 05/29/2017] [Accepted: 06/22/2017] [Indexed: 11/30/2022]
Abstract
Trypanosomal diseases are in need of innovative therapies that exploit novel mechanisms of action. The cell surface of trypanosomatid parasites is characterized by a dense coat of glycoconjugates with important functions in host cell recognition, immune evasion, infectivity, and cell function. The nature of parasite surface glycans is highly dynamic and changes during differentiation and in response to different stimuli through the action of glycosyltransferases and glycosidases. Here we propose a new approach to antiparasitic drug discovery that involves the use of carbohydrate-binding agents that bind specifically to cell-surface glycans, giving rise to cytotoxic events and parasite death. The potential and limitations of this strategy are addressed with a specific focus on the treatment of sleeping sickness.
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Affiliation(s)
- Víctor M Castillo-Acosta
- Instituto de Parasitología y Biomedicina 'López-Neyra', Consejo Superior de Investigaciones Científicas, Parque Tecnológico de Ciencias de la Salud, Avenida del Conocimiento, s/n 18016-Armilla (Granada), Spain
| | - Jan Balzarini
- Rega Institute for Medical Research, KU Leuven, Herestraat 49, B-3000 Leuven, Belgium
| | - Dolores González-Pacanowska
- Instituto de Parasitología y Biomedicina 'López-Neyra', Consejo Superior de Investigaciones Científicas, Parque Tecnológico de Ciencias de la Salud, Avenida del Conocimiento, s/n 18016-Armilla (Granada), Spain.
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27
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Ramírez AS, Boilevin J, Lin CW, Ha Gan B, Janser D, Aebi M, Darbre T, Reymond JL, Locher KP. Chemo-enzymatic synthesis of lipid-linked GlcNAc2Man5 oligosaccharides using recombinant Alg1, Alg2 and Alg11 proteins. Glycobiology 2017; 27:726-733. [PMID: 28575298 PMCID: PMC5881667 DOI: 10.1093/glycob/cwx045] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 05/10/2017] [Accepted: 05/27/2017] [Indexed: 11/14/2022] Open
Abstract
The biosynthesis of eukaryotic lipid-linked oligosaccharides (LLOs) that act as donor substrates in eukaryotic protein N-glycosylation starts on the cytoplasmic side of the endoplasmic reticulum and includes the sequential addition of five mannose units to dolichol-pyrophosphate-GlcNAc2. These reactions are catalyzed by the Alg1, Alg2 and Alg11 gene products and yield Dol-PP-GlcNAc2Man5, an LLO intermediate that is subsequently flipped to the lumen of the endoplasmic reticulum. While the purification of active Alg1 has previously been described, Alg11 and Alg2 have been mostly studied in vivo. We here describe the expression and purification of functional, full length Alg2 protein. Along with the purified soluble domains Alg1 and Alg11, we used Alg2 to chemo-enzymatically generate Dol-PP-GlcNAc2Man5 analogs starting from synthetic LLOs containing a chitobiose moiety coupled to oligoprenyl carriers of distinct lengths (C10, C15, C20 and C25). We found that while the addition of the first mannose unit by Alg1 was successful with all of the LLO molecules, the Alg2-catalyzed reaction was only efficient if the acceptor LLOs contained a sufficiently long lipid tail of four or five isoprenyl units (C20 and C25). Following conversion with Alg11, the resulting C20 or C25 -containing GlcNAc2Man5 LLO analogs were successfully used as donor substrates of purified single-subunit oligosaccharyltransferase STT3A from Trypanosoma brucei. Our results provide a chemo-enzymatic method for the generation of eukaryotic LLO analogs and are the basis of subsequent mechanistic studies of the enigmatic Alg2 reaction mechanism.
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Affiliation(s)
- Ana S Ramírez
- Department of Biology, Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), Schafmattstrasse 20, CH-8093 Zürich, Switzerland
| | - Jérémy Boilevin
- Department of Chemistry and Biochemistry, University of Berne, CH-3012 Berne, Switzerland
| | - Chia-Wei Lin
- Institute of Microbiology, Eidgenössische Technische Hochschule (ETH), CH-8093 Zürich, Switzerland
| | - Bee Ha Gan
- Department of Chemistry and Biochemistry, University of Berne, CH-3012 Berne, Switzerland
| | - Daniel Janser
- Department of Biology, Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), Schafmattstrasse 20, CH-8093 Zürich, Switzerland
| | - Markus Aebi
- Institute of Microbiology, Eidgenössische Technische Hochschule (ETH), CH-8093 Zürich, Switzerland
| | - Tamis Darbre
- Department of Chemistry and Biochemistry, University of Berne, CH-3012 Berne, Switzerland
| | - Jean-Louis Reymond
- Department of Chemistry and Biochemistry, University of Berne, CH-3012 Berne, Switzerland
| | - Kaspar P Locher
- Department of Biology, Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), Schafmattstrasse 20, CH-8093 Zürich, Switzerland
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28
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Field MC, Horn D, Fairlamb AH, Ferguson MAJ, Gray DW, Read KD, De Rycker M, Torrie LS, Wyatt PG, Wyllie S, Gilbert IH. Anti-trypanosomatid drug discovery: an ongoing challenge and a continuing need. Nat Rev Microbiol 2017; 15:217-231. [PMID: 28239154 PMCID: PMC5582623 DOI: 10.1038/nrmicro.2016.193] [Citation(s) in RCA: 265] [Impact Index Per Article: 37.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The WHO recognizes human African trypanosomiasis, Chagas disease and the leishmaniases as neglected tropical diseases. These diseases are caused by parasitic trypanosomatids and range in severity from mild and self-curing to near invariably fatal. Public health advances have substantially decreased the effect of these diseases in recent decades but alone will not eliminate them. In this Review, we discuss why new drugs against trypanosomatids are required, approaches that are under investigation to develop new drugs and why the drug discovery pipeline remains essentially unfilled. In addition, we consider the important challenges to drug discovery strategies and the new technologies that can address them. The combination of new drugs, new technologies and public health initiatives is essential for the management, and hopefully eventual elimination, of trypanosomatid diseases from the human population.
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Affiliation(s)
- Mark C Field
- Wellcome Centre for Anti-Infectives Research, University of Dundee, Dundee DD1 5EH, UK
| | - David Horn
- Wellcome Centre for Anti-Infectives Research, University of Dundee, Dundee DD1 5EH, UK
| | - Alan H Fairlamb
- Wellcome Centre for Anti-Infectives Research, University of Dundee, Dundee DD1 5EH, UK
| | - Michael A J Ferguson
- Wellcome Centre for Anti-Infectives Research, University of Dundee, Dundee DD1 5EH, UK
| | - David W Gray
- Wellcome Centre for Anti-Infectives Research, University of Dundee, Dundee DD1 5EH, UK
| | - Kevin D Read
- Wellcome Centre for Anti-Infectives Research, University of Dundee, Dundee DD1 5EH, UK
| | - Manu De Rycker
- Wellcome Centre for Anti-Infectives Research, University of Dundee, Dundee DD1 5EH, UK
| | - Leah S Torrie
- Wellcome Centre for Anti-Infectives Research, University of Dundee, Dundee DD1 5EH, UK
| | - Paul G Wyatt
- Wellcome Centre for Anti-Infectives Research, University of Dundee, Dundee DD1 5EH, UK
| | - Susan Wyllie
- Wellcome Centre for Anti-Infectives Research, University of Dundee, Dundee DD1 5EH, UK
| | - Ian H Gilbert
- Wellcome Centre for Anti-Infectives Research, University of Dundee, Dundee DD1 5EH, UK
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29
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Gottier P, Gonzalez-Salgado A, Menon AK, Liu YC, Acosta-Serrano A, Bütikofer P. RFT1 Protein Affects Glycosylphosphatidylinositol (GPI) Anchor Glycosylation. J Biol Chem 2016; 292:1103-1111. [PMID: 27927990 DOI: 10.1074/jbc.m116.758367] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 11/17/2016] [Indexed: 12/16/2022] Open
Abstract
The membrane protein RFT1 is essential for normal protein N-glycosylation, but its precise function is not known. RFT1 was originally proposed to translocate the glycolipid Man5GlcNAc2-PP-dolichol (needed to synthesize N-glycan precursors) across the endoplasmic reticulum membrane, but subsequent studies showed that it does not play a direct role in transport. In contrast to the situation in yeast, RFT1 is not essential for growth of the parasitic protozoan Trypanosoma brucei, enabling the study of its function in a null background. We now report that lack of T. brucei RFT1 (TbRFT1) not only affects protein N-glycosylation but also glycosylphosphatidylinositol (GPI) anchor side-chain modification. Analysis by immunoblotting, metabolic labeling, and mass spectrometry demonstrated that the major GPI-anchored proteins of T. brucei procyclic forms have truncated GPI anchor side chains in TbRFT1 null parasites when compared with wild-type cells, a defect that is corrected by expressing a tagged copy of TbRFT1 in the null background. In vivo and in vitro labeling experiments using radiolabeled GPI precursors showed that GPI underglycosylation was not the result of decreased formation of the GPI precursor lipid or defective galactosylation of GPI intermediates in the endoplasmic reticulum, but rather due to modifications that are expected to occur in the Golgi apparatus. Unexpectedly, immunofluorescence microscopy localized TbRFT1 to both the endoplasmic reticulum and the Golgi, consistent with the proposal that TbRFT1 plays a direct or indirect role in GPI anchor glycosylation in the Golgi apparatus. Our results implicate RFT1 in a wider range of glycosylation processes than previously appreciated.
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Affiliation(s)
- Petra Gottier
- From the Institute of Biochemistry and Molecular Medicine and.,Graduate School of Cellular and Biochemical Sciences, University of Bern, 3012 Bern, Switzerland
| | | | - Anant K Menon
- the Department of Biochemistry, Weill Cornell Medical College, New York, New York 10065, and
| | | | - Alvaro Acosta-Serrano
- the Departments of Parasitology and.,Vector Biology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, United Kingdom
| | - Peter Bütikofer
- From the Institute of Biochemistry and Molecular Medicine and
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30
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Complementation of an aglB Mutant of Methanococcus maripaludis with Heterologous Oligosaccharyltransferases. PLoS One 2016; 11:e0167611. [PMID: 27907170 PMCID: PMC5131992 DOI: 10.1371/journal.pone.0167611] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Accepted: 11/17/2016] [Indexed: 01/04/2023] Open
Abstract
The oligosaccharyltransferase is the signature enzyme for N-linked glycosylation in all domains of life. In Archaea, this enzyme termed AglB, is responsible for transferring lipid carrier-linked glycans to select asparagine residues in a variety of target proteins including archaellins, S-layer proteins and pilins. This study investigated the ability of a variety of AglBs to compensate for the oligosaccharyltransferase activity in Methanococcus maripaludis deleted for aglB, using archaellin FlaB2 as the reporter protein since all archaellins in Mc. maripaludis are modified at multiple sites by an N-linked tetrasaccharide and this modification is required for archaellation. In the Mc. maripaludis ΔaglB strain FlaB2 runs as at a smaller apparent molecular weight in western blots and is nonarchaellated. We demonstrate that AglBs from Methanococcus voltae and Methanothermococcus thermolithotrophicus functionally replaced the oligosaccharyltransferase activity missing in the Mc. maripaludis ΔaglB strain, both returning the apparent molecular weight of FlaB2 to wildtype size and restoring archaellation. This demonstrates that AglB from Mc. voltae has a relaxed specificity for the linking sugar of the transferred glycan since while the N-linked glycan present in Mc. voltae is similar to that of Mc. maripaludis, the Mc. voltae glycan uses N-acetylglucosamine as the linking sugar. In Mc. maripaludis that role is held by N-acetylgalactosamine. This study also identifies aglB from Mtc. thermolithotrophicus for the first time by its activity. Attempts to use AglB from Methanocaldococcus jannaschii, Haloferax volcanii or Sulfolobus acidocaldarius to functionally replace the oligosaccharyltransferase activity missing in the Mc. maripaludis ΔaglB strain were unsuccessful.
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31
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Brosson S, Fontaine F, Vermeersch M, Perez-Morga D, Pays E, Bousbata S, Salmon D. Specific Endocytosis Blockade of Trypanosoma cruzi Exposed to a Poly-LAcNAc Binding Lectin Suggests that Lectin-Sugar Interactions Participate to Receptor-Mediated Endocytosis. PLoS One 2016; 11:e0163302. [PMID: 27685262 PMCID: PMC5042520 DOI: 10.1371/journal.pone.0163302] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Accepted: 09/07/2016] [Indexed: 12/25/2022] Open
Abstract
Trypanosoma cruzi is a protozoan parasite transmitted by a triatomine insect, and causing human Chagas disease in South America. This parasite undergoes a complex life cycle alternating between non-proliferative and dividing forms. Owing to their high energy requirement, replicative epimastigotes of the insect midgut display high endocytic activity. This activity is mainly restricted to the cytostome, by which the cargo is taken up and sorted through the endosomal vesicular network to be delivered to reservosomes, the final lysosomal-like compartments. In African trypanosomes tomato lectin (TL) and ricin, respectively specific to poly-N-acetyllactosamine (poly-LacNAc) and β-D-galactose, allowed the identification of giant chains of poly-LacNAc in N-glycoproteins of the endocytic pathway. We show that in T. cruzi epimastigote forms also, glycoproteins of the endocytic pathway are characterized by the presence of N-linked glycans binding to both ricin and TL. Affinity chromatography using both TL and Griffonia simplicifolia lectin II (GSLII), specific to non-reducing terminal residue of N-acetylglucosamine (GlcNAc), led to an enrichment of glycoproteins of the trypanosomal endocytic pathway. Incubation of live parasites with TL, which selectively bound to the cytostome/cytopharynx, specifically inhibited endocytosis of transferrin (Tf) but not dextran, a marker of fluid endocytosis. Taken together, our data suggest that N-glycan modification of endocytic components plays a crucial role in receptor-mediated endocytosis of T. cruzi.
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Affiliation(s)
- Sébastien Brosson
- Laboratory of Molecular Parasitology, Institute of Molecular Biology and Medicine, Université Libre de Bruxelles, 12 rue des Professeurs Jeener et Brachet, B-6041 Gosselies, Belgium
| | - Frédéric Fontaine
- Laboratory of Molecular Parasitology, Institute of Molecular Biology and Medicine, Université Libre de Bruxelles, 12 rue des Professeurs Jeener et Brachet, B-6041 Gosselies, Belgium
| | - Marjorie Vermeersch
- Center for Microscopy and Molecular Imaging-CMMI, Université Libre de Bruxelles, 8 rue Adrienne Bolland, B-6041 Gosselies, Belgium
| | - David Perez-Morga
- Laboratory of Molecular Parasitology, Institute of Molecular Biology and Medicine, Université Libre de Bruxelles, 12 rue des Professeurs Jeener et Brachet, B-6041 Gosselies, Belgium
- Center for Microscopy and Molecular Imaging-CMMI, Université Libre de Bruxelles, 8 rue Adrienne Bolland, B-6041 Gosselies, Belgium
| | - Etienne Pays
- Laboratory of Molecular Parasitology, Institute of Molecular Biology and Medicine, Université Libre de Bruxelles, 12 rue des Professeurs Jeener et Brachet, B-6041 Gosselies, Belgium
| | - Sabrina Bousbata
- Laboratory of Molecular Parasitology, Institute of Molecular Biology and Medicine, Université Libre de Bruxelles, 12 rue des Professeurs Jeener et Brachet, B-6041 Gosselies, Belgium
- * E-mail: (DS); (SB)
| | - Didier Salmon
- Laboratory of Molecular Parasitology, Institute of Molecular Biology and Medicine, Université Libre de Bruxelles, 12 rue des Professeurs Jeener et Brachet, B-6041 Gosselies, Belgium
- Institute of Medical Biochemistry Leopoldo de Meis, Centro de Ciências e da Saúde, Federal University of Rio de Janeiro, Av. Brigadeiro Trompowsky, Rio de Janeiro, 21941-590, Brazil
- * E-mail: (DS); (SB)
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Castillo-Acosta VM, Ruiz-Pérez LM, Etxebarria J, Reichardt NC, Navarro M, Igarashi Y, Liekens S, Balzarini J, González-Pacanowska D. Carbohydrate-Binding Non-Peptidic Pradimicins for the Treatment of Acute Sleeping Sickness in Murine Models. PLoS Pathog 2016; 12:e1005851. [PMID: 27662652 PMCID: PMC5035034 DOI: 10.1371/journal.ppat.1005851] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 08/08/2016] [Indexed: 12/21/2022] Open
Abstract
Current treatments available for African sleeping sickness or human African trypanosomiasis (HAT) are limited, with poor efficacy and unacceptable safety profiles. Here, we report a new approach to address treatment of this disease based on the use of compounds that bind to parasite surface glycans leading to rapid killing of trypanosomes. Pradimicin and its derivatives are non-peptidic carbohydrate-binding agents that adhere to the carbohydrate moiety of the parasite surface glycoproteins inducing parasite lysis in vitro. Notably, pradimicin S has good pharmaceutical properties and enables cure of an acute form of the disease in mice. By inducing resistance in vitro we have established that the composition of the sugars attached to the variant surface glycoproteins are critical to the mode of action of pradimicins and play an important role in infectivity. The compounds identified represent a novel approach to develop drugs to treat HAT.
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Affiliation(s)
- Víctor M. Castillo-Acosta
- Instituto de Parasitología y Biomedicina “López-Neyra”, Consejo Superior de Investigaciones Científicas, Parque Tecnológico de Ciencias de la Salud, Armilla (Granada), Spain
| | - Luis M. Ruiz-Pérez
- Instituto de Parasitología y Biomedicina “López-Neyra”, Consejo Superior de Investigaciones Científicas, Parque Tecnológico de Ciencias de la Salud, Armilla (Granada), Spain
| | - Juan Etxebarria
- Glycotechnology Laboratory, CIC biomaGUNE, Parque Científico y Tecnológico de Gipuzkoa, San Sebastián, Spain
| | - Niels C. Reichardt
- Glycotechnology Laboratory, CIC biomaGUNE, Parque Científico y Tecnológico de Gipuzkoa, San Sebastián, Spain
- CIBER of Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), San Sebastián, Spain
| | - Miguel Navarro
- Instituto de Parasitología y Biomedicina “López-Neyra”, Consejo Superior de Investigaciones Científicas, Parque Tecnológico de Ciencias de la Salud, Armilla (Granada), Spain
| | - Yasuhiro Igarashi
- Biotechnology Research Center, Toyama Prefectural University, Imizu, Toyama, Japan
| | - Sandra Liekens
- KU Leuven, Rega Institute for Medical Research, Leuven, Belgium
| | - Jan Balzarini
- KU Leuven, Rega Institute for Medical Research, Leuven, Belgium
| | - Dolores González-Pacanowska
- Instituto de Parasitología y Biomedicina “López-Neyra”, Consejo Superior de Investigaciones Científicas, Parque Tecnológico de Ciencias de la Salud, Armilla (Granada), Spain
- * E-mail:
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Tiengwe C, Muratore KA, Bangs JD. Surface proteins, ERAD and antigenic variation in Trypanosoma brucei. Cell Microbiol 2016; 18:1673-1688. [PMID: 27110662 DOI: 10.1111/cmi.12605] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Revised: 03/20/2016] [Accepted: 04/12/2016] [Indexed: 12/11/2022]
Abstract
Variant surface glycoprotein (VSG) is central to antigenic variation in African trypanosomes. Although much prior work documents that VSG is efficiently synthesized and exported to the cell surface, it was recently claimed that 2-3 fold more is synthesized than required, the excess being eliminated by ER-Associated Degradation (ERAD) (Field et al., ). We now reinvestigate VSG turnover and find no evidence for rapid degradation, consistent with a model whereby VSG synthesis is precisely regulated to match requirements for a functional surface coat on each daughter cell. However, using a mutated version of the ESAG7 subunit of the transferrin receptor (E7:Ty) we confirm functional ERAD in trypanosomes. E7:Ty fails to assemble into transferrin receptors and accumulates in the ER, consistent with retention of misfolded protein, and its turnover is selectively rescued by the proteasomal inhibitor MG132. We also show that ER accumulation of E7:Ty does not induce an unfolded protein response. These data, along with the presence of ERAD orthologues in the Trypanosoma brucei genome, confirm ERAD in trypanosomes. We discuss scenarios in which ERAD could be critical to bloodstream parasites, and how these may have contributed to the evolution of antigenic variation in trypanosomes.
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Affiliation(s)
- Calvin Tiengwe
- Department of Microbiology and Immunology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo (SUNY), Buffalo, NY, 14214, USA
| | - Katherine A Muratore
- Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis-St. Paul, MN, 55455, USA
| | - James D Bangs
- Department of Microbiology and Immunology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo (SUNY), Buffalo, NY, 14214, USA.
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Damerow M, Graalfs F, Güther MLS, Mehlert A, Izquierdo L, Ferguson MAJ. A Gene of the β3-Glycosyltransferase Family Encodes N-Acetylglucosaminyltransferase II Function in Trypanosoma brucei. J Biol Chem 2016; 291:13834-45. [PMID: 27189951 PMCID: PMC4919465 DOI: 10.1074/jbc.m116.733246] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Indexed: 11/06/2022] Open
Abstract
The bloodstream form of the human pathogen Trypanosoma brucei expresses oligomannose, paucimannose, and complex N-linked glycans, including some exceptionally large poly-N-acetyllactosamine-containing structures. Despite the presence of complex N-glycans in this organism, no homologues of the canonical N-acetylglucosaminyltransferase I or II genes can be found in the T. brucei genome. These genes encode the activities that initiate the elaboration of the Manα1-3 and Manα1-6 arms, respectively, of the conserved trimannosyl-N-acetylchitobiosyl core of N-linked glycans. Previously, we identified a highly divergent T. brucei N-acetylglucosaminyltransferase I (TbGnTI) among a set of putative T. brucei glycosyltransferase genes belonging to the β3-glycosyltransferase superfamily (Damerow, M., Rodrigues, J. A., Wu, D., Güther, M. L., Mehlert, A., and Ferguson, M. A. (2014) J. Biol. Chem. 289, 9328-9339). Here, we demonstrate that TbGT15, another member of the same β3-glycosyltransferase family, encodes an equally divergent N-acetylglucosaminyltransferase II (TbGnTII) activity. In contrast to multicellular organisms, where GnTII activity is essential, TbGnTII null mutants of T. brucei grow in culture and are still infectious to animals. Characterization of the large poly-N-acetyllactosamine containing N-glycans of the TbGnTII null mutants by methylation linkage analysis suggests that, in wild-type parasites, the Manα1-6 arm of the conserved trimannosyl core may carry predominantly linear poly-N-acetyllactosamine chains, whereas the Manα1-3 arm may carry predominantly branched poly-N-acetyllactosamine chains. These results provide further detail on the structure and biosynthesis of complex N-glycans in an important human pathogen and provide a second example of the adaptation by trypanosomes of β3-glycosyltransferase family members to catalyze β1-2 glycosidic linkages.
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Affiliation(s)
- Manuela Damerow
- From the Division of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom
| | - Frauke Graalfs
- From the Division of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom
| | - M Lucia S Güther
- From the Division of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom
| | - Angela Mehlert
- From the Division of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom
| | - Luis Izquierdo
- From the Division of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom
| | - Michael A J Ferguson
- From the Division of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom
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Taguchi Y, Fujinami D, Kohda D. Comparative Analysis of Archaeal Lipid-linked Oligosaccharides That Serve as Oligosaccharide Donors for Asn Glycosylation. J Biol Chem 2016; 291:11042-54. [PMID: 27015803 DOI: 10.1074/jbc.m115.713156] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Indexed: 11/06/2022] Open
Abstract
The glycosylation of asparagine residues is the predominant protein modification in all three domains of life. An oligosaccharide chain is preassembled on a lipid-phospho carrier and transferred onto asparagine residues by the action of a membrane-bound enzyme, oligosaccharyltransferase. The oligosaccharide donor for the oligosaccharyl transfer reaction is dolichol-diphosphate-oligosaccharide in Eukaryota and polyprenol-diphosphate-oligosaccharide in Eubacteria. The donor in some archaeal species was reportedly dolichol-monophosphate-oligosaccharide. Thus, the difference in the number of phosphate groups aroused interest in whether the use of the dolichol-monophosphate type donors is widespread in the domain Archaea. Currently, all of the archaeal species with identified oligosaccharide donors have belonged to the phylum Euryarchaeota. Here, we analyzed the donor structures of two species belonging to the phylum Crenarchaeota, Pyrobaculum calidifontis and Sulfolobus solfataricus, in addition to two species from the Euryarchaeota, Pyrococcus furiosus and Archaeoglobus fulgidus The electrospray ionization tandem mass spectrometry analyses confirmed that the two euryarchaeal oligosaccharide donors were the dolichol-monophosphate type and newly revealed that the two crenarchaeal oligosaccharide donors were the dolichol-diphosphate type. This novel finding is consistent with the hypothesis that the ancestor of Eukaryota is rooted within the TACK (Thaum-, Aig-, Cren-, and Korarchaeota) superphylum, which includes Crenarchaea. Our comprehensive study also revealed that one archaeal species could contain two distinct oligosaccharide donors for the oligosaccharyl transfer reaction. The A. fulgidus cells contained two oligosaccharide donors bearing oligosaccharide moieties with different backbone structures, and the S. solfataricus cells contained two oligosaccharide donors bearing stereochemically different dolichol chains.
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Affiliation(s)
| | | | - Daisuke Kohda
- From the Division of Structural Biology and Research Centers for Advanced Immunology and Live-Protein Dynamics, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582, Japan
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Schwede A, Macleod OJS, MacGregor P, Carrington M. How Does the VSG Coat of Bloodstream Form African Trypanosomes Interact with External Proteins? PLoS Pathog 2015; 11:e1005259. [PMID: 26719972 PMCID: PMC4697842 DOI: 10.1371/journal.ppat.1005259] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Variations on the statement “the variant surface glycoprotein (VSG) coat that covers the external face of the mammalian bloodstream form of Trypanosoma brucei acts a physical barrier” appear regularly in research articles and reviews. The concept of the impenetrable VSG coat is an attractive one, as it provides a clear model for understanding how a trypanosome population persists; each successive VSG protects the plasma membrane and is immunologically distinct from previous VSGs. What is the evidence that the VSG coat is an impenetrable barrier, and how do antibodies and other extracellular proteins interact with it? In this review, the nature of the extracellular surface of the bloodstream form trypanosome is described, and past experiments that investigated binding of antibodies and lectins to trypanosomes are analysed using knowledge of VSG sequence and structure that was unavailable when the experiments were performed. Epitopes for some VSG monoclonal antibodies are mapped as far as possible from previous experimental data, onto models of VSG structures. The binding of lectins to some, but not to other, VSGs is revisited with more recent knowledge of the location and nature of N-linked oligosaccharides. The conclusions are: (i) Much of the variation observed in earlier experiments can be explained by the identity of the individual VSGs. (ii) Much of an individual VSG is accessible to antibodies, and the barrier that prevents access to the cell surface is probably at the base of the VSG N-terminal domain, approximately 5 nm from the plasma membrane. This second conclusion highlights a gap in our understanding of how the VSG coat works, as several plasma membrane proteins with large extracellular domains are very unlikely to be hidden from host antibodies by VSG. African trypanosomes have evolved two key strategies to prevent killing by the host immune response and, thus, maintain a long-term infection in a mammal. Both are based on a densely packed coat of a single protein, the variant surface glycoprotein (VSG), which covers the entire extracellular surface of the cell. The first strategy is antigenic variation, through which individual cells switch the identity of the expressed VSG at a low frequency and are selected by the host immune response. If the VSG is novel, the trypanosome proliferates, maintaining the infection; if it doesn't switch, or if the new VSG is not novel, it will be killed. In the second strategy, the VSG acts as a protective barrier, shielding the cell from innate and adaptive immune factors until there is an overwhelming titre of antibodies recognising the expressed VSG. In this review, the VSG coat is modelled, and past experiments that investigated how it protected the trypanosome are revisited using current knowledge of VSG sequence and structure. The conclusions are: (i) the identity of the individual VSGs explains early experimental variation; (ii) most of the VSG molecule is accessible to antibodies. This second conclusion highlights a gap in our understanding of how the VSG coat works, as several plasma membrane proteins with large extracellular domains are very unlikely to be hidden from host antibodies by VSG.
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Affiliation(s)
- Angela Schwede
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | | | - Paula MacGregor
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Mark Carrington
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
- * E-mail:
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37
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Zacchi LF, Schulz BL. N-glycoprotein macroheterogeneity: biological implications and proteomic characterization. Glycoconj J 2015; 33:359-76. [DOI: 10.1007/s10719-015-9641-3] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Revised: 11/04/2015] [Accepted: 11/20/2015] [Indexed: 10/22/2022]
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38
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Characterization of an African trypanosome mutant refractory to lectin-induced death. Biochem Biophys Rep 2015; 4:33-38. [PMID: 26393238 PMCID: PMC4574508 DOI: 10.1016/j.bbrep.2015.08.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Incubation of African trypanosomes with the lectin concanavalin A (conA) leads to alteration in cellular DNA content, DNA degradation, and surface membrane blebbing. Here, we report the generation and characterization of a conA-refractory Trypanosoma brucei line. These insect stage parasites were resistant to conA killing, with a median lethal dose at least 50-fold greater than the parental line. Fluorescence-based experiments revealed that the resistant cells bound less lectin when compared to the parental line. Western blotting and mass spectrometry confirmed that the resistant line lacked an N-glycan required for conA binding on the cellular receptors, EP procyclin proteins. The failure to N-glycosylate the EP procyclins was not the consequence of altered N-glycan precursor biosynthesis, as another glycosylated protein (Fla1p) was normally modified. These findings support the likelihood that resistance to conA was a consequence of failure to bind the lectin trigger. Concanavalin A is toxic to Trypanosoma brucei. A mutant has been identified that is resistant to the concanavalin A killing. The mutant does not properly N-glycosylate the major lectin receptor, hence its resistance.
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Rodrigues JA, Acosta-Serrano A, Aebi M, Ferguson MAJ, Routier FH, Schiller I, Soares S, Spencer D, Titz A, Wilson IBH, Izquierdo L. Parasite Glycobiology: A Bittersweet Symphony. PLoS Pathog 2015; 11:e1005169. [PMID: 26562305 PMCID: PMC4642930 DOI: 10.1371/journal.ppat.1005169] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Affiliation(s)
- Joao A. Rodrigues
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Lisboa, Portugal
- * E-mail: (JAR); (LI)
| | - Alvaro Acosta-Serrano
- Department of Parasitology & Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Markus Aebi
- Institute of Microbiology, Department of Biology, Swiss Federal Institute of Technology, ETH Zurich, Zurich, Switzerland
| | - Michael A. J. Ferguson
- Division of Biological Chemistry and Drug Discovery, The College of Life Sciences, University of Dundee, Dundee, United Kingdom
| | | | | | | | - Daniel Spencer
- Ludger Ltd., Culham Science Centre, Abingdon, Oxfordshire, United Kingdom
| | - Alexander Titz
- Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Saarbrücken, Germany
| | | | - Luis Izquierdo
- ISGlobal, Barcelona Centre for International Health Research (CRESIB), Hospital Clínic - Universitat de Barcelona, Barcelona, Spain
- * E-mail: (JAR); (LI)
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40
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Harada Y, Hirayama H, Suzuki T. Generation and degradation of free asparagine-linked glycans. Cell Mol Life Sci 2015; 72:2509-33. [PMID: 25772500 PMCID: PMC11113800 DOI: 10.1007/s00018-015-1881-7] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2014] [Revised: 02/19/2015] [Accepted: 03/05/2015] [Indexed: 10/23/2022]
Abstract
Asparagine (N)-linked protein glycosylation, which takes place in the eukaryotic endoplasmic reticulum (ER), is important for protein folding, quality control and the intracellular trafficking of secretory and membrane proteins. It is known that, during N-glycosylation, considerable amounts of lipid-linked oligosaccharides (LLOs), the glycan donor substrates for N-glycosylation, are hydrolyzed to form free N-glycans (FNGs) by unidentified mechanisms. FNGs are also generated in the cytosol by the enzymatic deglycosylation of misfolded glycoproteins during ER-associated degradation. FNGs derived from LLOs and misfolded glycoproteins are eventually merged into one pool in the cytosol and the various glycan structures are processed to a near homogenous glycoform. This article summarizes the current state of our knowledge concerning the formation and catabolism of FNGs.
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Affiliation(s)
- Yoichiro Harada
- Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 Japan
| | - Hiroto Hirayama
- Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 Japan
| | - Tadashi Suzuki
- Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 Japan
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41
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Xu Y, Bailey UM, Schulz BL. Automated measurement of site-specific N
-glycosylation occupancy with SWATH-MS. Proteomics 2015; 15:2177-86. [DOI: 10.1002/pmic.201400465] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 01/08/2015] [Accepted: 02/27/2015] [Indexed: 12/21/2022]
Affiliation(s)
- Ying Xu
- School of Chemistry and Molecular Biosciences; The University of Queensland; Brisbane Queensland Australia
| | - Ulla-Maja Bailey
- School of Chemistry and Molecular Biosciences; The University of Queensland; Brisbane Queensland Australia
| | - Benjamin L. Schulz
- School of Chemistry and Molecular Biosciences; The University of Queensland; Brisbane Queensland Australia
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42
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Castillo-Acosta VM, Ruiz-Pérez LM, Van Damme EJM, Balzarini J, González-Pacanowska D. Exposure of Trypanosoma brucei to an N-acetylglucosamine-binding lectin induces VSG switching and glycosylation defects resulting in reduced infectivity. PLoS Negl Trop Dis 2015; 9:e0003612. [PMID: 25746926 PMCID: PMC4351956 DOI: 10.1371/journal.pntd.0003612] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Accepted: 02/10/2015] [Indexed: 12/22/2022] Open
Abstract
Trypanosoma brucei variant surface glycoproteins (VSG) are glycosylated by both paucimannose and oligomannose structures which are involved in the formation of a protective barrier against the immune system. Here, we report that the stinging nettle lectin (UDA), with predominant N-acetylglucosamine-binding specificity, interacts with glycosylated VSGs and kills parasites by provoking defects in endocytosis together with impaired cytokinesis. Prolonged exposure to UDA induced parasite resistance based on a diminished capacity to bind the lectin due to an enrichment of biantennary paucimannose and a reduction of triantennary oligomannose structures. Two molecular mechanisms involved in resistance were identified: VSG switching and modifications in N-glycan composition. Glycosylation defects were correlated with the down-regulation of the TbSTT3A and/or TbSTT3B genes (coding for oligosaccharyltransferases A and B, respectively) responsible for glycan specificity. Furthermore, UDA-resistant trypanosomes exhibited severely impaired infectivity indicating that the resistant phenotype entails a substantial fitness cost. The results obtained further support the modification of surface glycan composition resulting from down-regulation of the genes coding for oligosaccharyltransferases as a general resistance mechanism in response to prolonged exposure to carbohydrate-binding agents.
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Affiliation(s)
- Víctor M. Castillo-Acosta
- Instituto de Parasitología y Biomedicina “López-Neyra”, Consejo Superior de Investigaciones Científicas, Parque Tecnológico de Ciencias de la Salud, Granada, Spain
| | - Luis M. Ruiz-Pérez
- Instituto de Parasitología y Biomedicina “López-Neyra”, Consejo Superior de Investigaciones Científicas, Parque Tecnológico de Ciencias de la Salud, Granada, Spain
| | - Els J. M. Van Damme
- Laboratory of Biochemistry and Glycobiology, Department of Molecular Biotechnology, Ghent University, Ghent, Belgium
| | - Jan Balzarini
- Rega Institute for Medical Research, KU Leuven, Leuven, Belgium
| | - Dolores González-Pacanowska
- Instituto de Parasitología y Biomedicina “López-Neyra”, Consejo Superior de Investigaciones Científicas, Parque Tecnológico de Ciencias de la Salud, Granada, Spain
- * E-mail:
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43
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Zhang W, Cao W, Huang J, Wang H, Wang J, Xie C, Yang P. PNGase F-mediated incorporation of 18O into glycans for relative glycan quantitation. Analyst 2015; 140:1082-9. [DOI: 10.1039/c4an02073a] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
An enzymatic four 18O-labeling strategy based on PNGase F-catalyzed glycan 18O-labeling (PCGOL) developed in this work can be used for simultaneous quantification of glycans, non-glycopeptides and glycopeptides in a single workflow.
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Affiliation(s)
- Wei Zhang
- Department of Chemistry
- Fudan University
- Shanghai 200433
- P. R. China
- Institutes of Biomedical Sciences
| | - Weiqian Cao
- Department of Chemistry
- Fudan University
- Shanghai 200433
- P. R. China
- Institutes of Biomedical Sciences
| | - Jiangming Huang
- Department of Chemistry
- Fudan University
- Shanghai 200433
- P. R. China
| | - Hong Wang
- Department of Chemistry
- Fudan University
- Shanghai 200433
- P. R. China
- Institutes of Biomedical Sciences
| | - Ji Wang
- Institutes of Biomedical Sciences
- Fudan University
- Shanghai 200032
- P. R. China
| | - Chen Xie
- Department of Chemistry
- Fudan University
- Shanghai 200433
- P. R. China
| | - Pengyuan Yang
- Department of Chemistry
- Fudan University
- Shanghai 200433
- P. R. China
- Institutes of Biomedical Sciences
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44
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Samuelson J, Robbins PW. Effects of N-glycan precursor length diversity on quality control of protein folding and on protein glycosylation. Semin Cell Dev Biol 2014; 41:121-8. [PMID: 25475176 DOI: 10.1016/j.semcdb.2014.11.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 11/24/2014] [Accepted: 11/26/2014] [Indexed: 01/24/2023]
Abstract
Asparagine-linked glycans (N-glycans) of medically important protists have much to tell us about the evolution of N-glycosylation and of N-glycan-dependent quality control (N-glycan QC) of protein folding in the endoplasmic reticulum. While host N-glycans are built upon a dolichol-pyrophosphate-linked precursor with 14 sugars (Glc3Man9GlcNAc2), protist N-glycan precursors vary from Glc3Man9GlcNAc2 (Acanthamoeba) to Man9GlcNAc2 (Trypanosoma) to Glc3Man5GlcNAc2 (Toxoplasma) to Man5GlcNAc2 (Entamoeba, Trichomonas, and Eimeria) to GlcNAc2 (Plasmodium and Giardia) to zero (Theileria). As related organisms have differing N-glycan lengths (e.g. Toxoplasma, Eimeria, Plasmodium, and Theileria), the present N-glycan variation is based upon secondary loss of Alg genes, which encode enzymes that add sugars to the N-glycan precursor. An N-glycan precursor with Man5GlcNAc2 is necessary but not sufficient for N-glycan QC, which is predicted by the presence of the UDP-glucose:glucosyltransferase (UGGT) plus calreticulin and/or calnexin. As many parasites lack glucose in their N-glycan precursor, UGGT product may be identified by inhibition of glucosidase II. The presence of an armless calnexin in Toxoplasma suggests secondary loss of N-glycan QC from coccidia. Positive selection for N-glycan sites occurs in secreted proteins of organisms with N-glycan QC and is based upon an increased likelihood of threonine but not serine in the +2 position versus asparagine. In contrast, there appears to be selection against N-glycan length in Plasmodium and N-glycan site density in Toxoplasma. Finally, there is suggestive evidence for N-glycan-dependent ERAD in Trichomonas, which glycosylates and degrades the exogenous reporter mutant carboxypeptidase Y (CPY*).
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Affiliation(s)
- John Samuelson
- Department of Molecular and Cell Biology, Boston University Goldman School of Dental Medicine, 72 East Concord St, Evans 425, Boston, MA 02118, USA.
| | - Phillips W Robbins
- Department of Molecular and Cell Biology, Boston University Goldman School of Dental Medicine, 72 East Concord St, Evans 425, Boston, MA 02118, USA.
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Izquierdo L, Acosta-Serrano A, Mehlert A, Ferguson MA. Identification of a glycosylphosphatidylinositol anchor-modifying β1-3 galactosyltransferase in Trypanosoma brucei. Glycobiology 2014; 25:438-47. [PMID: 25467966 PMCID: PMC4339879 DOI: 10.1093/glycob/cwu131] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Trypanosoma brucei is the causative agent of human African sleeping sickness and the cattle disease nagana. Trypanosoma brucei is dependent on glycoproteins for its survival and infectivity throughout its life cycle. Here we report the functional characterization of TbGT3, a glycosyltransferase expressed in the bloodstream and procyclic form of the parasite. Bloodstream and procyclic form TbGT3 conditional null mutants were created and both exhibited normal growth under permissive and nonpermissive conditions. Under nonpermissive conditions, the normal glycosylation of the major glycoprotein of bloodstream form T. brucei, the variant surface glycoprotein and the absence of major alterations in lectin binding to other glycoproteins suggested that the major function of TbGT3 occurs in the procyclic form of the parasite. Consistent with this, the major surface glycoprotein of the procyclic form, procyclin, exhibited a marked reduction in molecular weight due to changes in glycosylphosphatidylinositol (GPI) anchor side chains. Structural analysis of the mutant procyclin GPI anchors indicated that TbGT3 encodes a UDP-Gal: β-GlcNAc-GPI β1-3 Gal transferase. Despite the alterations in GPI anchor side chains, TbGT3 conditional null mutants remained infectious to tsetse flies under nonpermissive conditions.
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Affiliation(s)
- Luis Izquierdo
- Division of Biological Chemistry and Drug Discovery, The College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK Barcelona Centre for International Health Research, CRESIB, Hospital Clínic-Universitat de Barcelona, Barcelona 08036, Spain
| | - Alvaro Acosta-Serrano
- Department of Parasitology Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK
| | - Angela Mehlert
- Division of Biological Chemistry and Drug Discovery, The College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Michael Aj Ferguson
- Division of Biological Chemistry and Drug Discovery, The College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
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46
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Glycoengineering of yeasts from the perspective of glycosylation efficiency. N Biotechnol 2014; 31:532-7. [DOI: 10.1016/j.nbt.2014.03.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 02/26/2014] [Accepted: 03/02/2014] [Indexed: 11/23/2022]
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47
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Endoplasmic reticulum stress responses in Leishmania. Mol Biochem Parasitol 2014; 197:1-8. [PMID: 25224909 DOI: 10.1016/j.molbiopara.2014.09.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Revised: 08/14/2014] [Accepted: 09/05/2014] [Indexed: 11/23/2022]
Abstract
Perturbation of endoplasmic reticulum (ER) homeostasis can lead to an accumulation of misfolded proteins within the ER lumen causing initiation of ER stress. To reestablish homeostasis and mitigate the stress, a series of adaptive intracellular signaling pathways termed the unfolded protein response (UPR) are activated. ER stress is of considerable interest to parasitologists because it takes place in parasites subjected to adverse environmental conditions. During a digenetic lifestyle, Leishmania parasites encounter and adapt to harsh environmental conditions that provide potential triggers of ER stress. These include nutrient deficiency, hypoxia, oxidative stress, changing pH, and shifts in temperature. Protozoan human pathogens, including the causative agents of trypanosomiasis, leishmaniasis, toxoplasmosis and malaria, contain a minimal conventional UPR network relative to higher eukaryotic cells. Three different signaling pathways in the ER stress response have been described in trypanosomatids: these pathways involve (i) the down-regulation of translation by a protein kinase RNA-like ER kinase (PERK), (ii) the ER-associated degradation (ERAD) pathway, and (iii) the spliced leader silencing (SLS) pathway and its target mRNAs. Under short-term ER stress, signaling from PERK activates autophagy, a cell survival response. But both chronic and unresolved ER stresses lead to initiation of apoptotic events and eventual cell death. This review presents the current understanding of the ER stress response in Leishmania with an emphasis on protein folding and ER quality control, unfolded protein response, autophagy as well as apoptosis in reference to the mammalian system.
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48
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Jarrell KF, Ding Y, Meyer BH, Albers SV, Kaminski L, Eichler J. N-linked glycosylation in Archaea: a structural, functional, and genetic analysis. Microbiol Mol Biol Rev 2014; 78:304-41. [PMID: 24847024 PMCID: PMC4054257 DOI: 10.1128/mmbr.00052-13] [Citation(s) in RCA: 151] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
N-glycosylation of proteins is one of the most prevalent posttranslational modifications in nature. Accordingly, a pathway with shared commonalities is found in all three domains of life. While excellent model systems have been developed for studying N-glycosylation in both Eukarya and Bacteria, an understanding of this process in Archaea was hampered until recently by a lack of effective molecular tools. However, within the last decade, impressive advances in the study of the archaeal version of this important pathway have been made for halophiles, methanogens, and thermoacidophiles, combining glycan structural information obtained by mass spectrometry with bioinformatic, genetic, biochemical, and enzymatic data. These studies reveal both features shared with the eukaryal and bacterial domains and novel archaeon-specific aspects. Unique features of N-glycosylation in Archaea include the presence of unusual dolichol lipid carriers, the use of a variety of linking sugars that connect the glycan to proteins, the presence of novel sugars as glycan constituents, the presence of two very different N-linked glycans attached to the same protein, and the ability to vary the N-glycan composition under different growth conditions. These advances are the focus of this review, with an emphasis on N-glycosylation pathways in Haloferax, Methanococcus, and Sulfolobus.
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Affiliation(s)
- Ken F Jarrell
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Yan Ding
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Benjamin H Meyer
- Molecular Biology of Archaea, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Sonja-Verena Albers
- Molecular Biology of Archaea, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Lina Kaminski
- Department of Life Sciences, Ben Gurion University, Beersheva, Israel
| | - Jerry Eichler
- Department of Life Sciences, Ben Gurion University, Beersheva, Israel
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49
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Manna PT, Boehm C, Leung KF, Natesan SK, Field MC. Life and times: synthesis, trafficking, and evolution of VSG. Trends Parasitol 2014; 30:251-8. [PMID: 24731931 PMCID: PMC4007029 DOI: 10.1016/j.pt.2014.03.004] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Revised: 03/14/2014] [Accepted: 03/14/2014] [Indexed: 11/30/2022]
Abstract
Evasion of the acquired immune response in African trypanosomes is principally mediated by antigenic variation, the sequential expression of distinct variant surface glycoproteins (VSGs) at extremely high density on the cell surface. Sequence diversity between VSGs facilitates escape of a subpopulation of trypanosomes from antibody-mediated killing. Significant advances have increased understanding of the mechanisms underpinning synthesis and maintenance of the VSG coat. In this review, we discuss the biosynthesis, trafficking, and turnover of VSG, emphasising those unusual mechanisms that act to maintain coat integrity and to protect against immunological attack. We also highlight new findings that suggest the presence of unique or highly divergent proteins that may offer therapeutic opportunities, as well as considering aspects of VSG biology that remain to be fully explored.
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Affiliation(s)
- Paul T Manna
- Division of Biological Chemistry and Drug Discovery, University of Dundee, Dundee, DD1 5EH, UK
| | - Cordula Boehm
- Division of Biological Chemistry and Drug Discovery, University of Dundee, Dundee, DD1 5EH, UK
| | - Ka Fai Leung
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QP, UK
| | - Senthil Kumar Natesan
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QP, UK
| | - Mark C Field
- Division of Biological Chemistry and Drug Discovery, University of Dundee, Dundee, DD1 5EH, UK.
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Damerow M, Rodrigues JA, Wu D, Güther MLS, Mehlert A, Ferguson MAJ. Identification and functional characterization of a highly divergent N-acetylglucosaminyltransferase I (TbGnTI) in Trypanosoma brucei. J Biol Chem 2014; 289:9328-39. [PMID: 24550396 PMCID: PMC3979372 DOI: 10.1074/jbc.m114.555029] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Trypanosoma brucei expresses a diverse repertoire of N-glycans, ranging from oligomannose and paucimannose structures to exceptionally large complex N-glycans. Despite the presence of the latter, no obvious homologues of known β1–4-galactosyltransferase or β1–2- or β1–6-N-acetylglucosaminyltransferase genes have been found in the parasite genome. However, we previously reported a family of putative UDP-sugar-dependent glycosyltransferases with similarity to the mammalian β1–3-glycosyltransferase family. Here we characterize one of these genes, TbGT11, and show that it encodes a Golgi apparatus resident UDP-GlcNAc:α3-d-mannoside β1–2-N-acetylglucosaminyltransferase I activity (TbGnTI). The bloodstream-form TbGT11 null mutant exhibited significantly modified protein N-glycans but normal growth in vitro and infectivity to rodents. In contrast to multicellular organisms, where the GnTI reaction is essential for biosynthesis of both complex and hybrid N-glycans, T. brucei TbGT11 null mutants expressed atypical “pseudohybrid” glycans, indicating that TbGnTII activity is not dependent on prior TbGnTI action. Using a functional in vitro assay, we showed that TbGnTI transfers UDP-GlcNAc to biantennary Man3GlcNAc2, but not to triantennary Man5GlcNAc2, which is the preferred substrate for metazoan GnTIs. Sequence alignment reveals that the T. brucei enzyme is far removed from the metazoan GnTI family and suggests that the parasite has adapted the β3-glycosyltransferase family to catalyze β1–2 linkages.
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Affiliation(s)
- Manuela Damerow
- From the Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom and
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