1
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Yang W, Ramadan S, Zu Y, Sun M, Huang X, Yu B. Chemical synthesis and functional evaluation of glycopeptides and glycoproteins containing rare glycosyl amino acid linkages. Nat Prod Rep 2024; 41:1403-1440. [PMID: 38888170 DOI: 10.1039/d4np00017j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/20/2024]
Abstract
Covering: 1987 to 2023Naturally existing glycoproteins through post-translational protein glycosylation are highly heterogeneous, which not only impedes the structure-function studies, but also hinders the development of their potential medical usage. Chemical synthesis represents one of the most powerful tools to provide the structurally well-defined glycoforms. Being the key step of glycoprotein synthesis, glycosylation usually takes place at serine, threonine, and asparagine residues, leading to the predominant formation of the O- and N-glycans, respectively. However, other amino acid residues containing oxygen, nitrogen, sulfur, and nucleophilic carbon atoms have also been found to be glycosylated. These diverse glycoprotein linkages, occurring from microorganisms to plants and animals, play also pivotal biological roles, such as in cell-cell recognition and communication. The availability of these homogenous rare glycopeptides and glycoproteins can help decipher the glyco-code for developing therapeutic agents. This review highlights the chemical approaches for assembly of the functional glycopeptides and glycoproteins bearing these "rare" carbohydrate-amino acid linkages between saccharide and canonical amino acid residues and their derivatives.
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Affiliation(s)
- Weizhun Yang
- School of Chemistry and Materials Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou 310024, China.
| | - Sherif Ramadan
- Department of Chemistry, Michigan State University, 578 S. Shaw Lane, East Lansing, Michigan 48824, USA.
| | - Yan Zu
- School of Chemistry and Materials Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou 310024, China.
| | - Mengxia Sun
- Department of Chemistry, Michigan State University, 578 S. Shaw Lane, East Lansing, Michigan 48824, USA.
| | - Xuefei Huang
- Department of Chemistry, Michigan State University, 578 S. Shaw Lane, East Lansing, Michigan 48824, USA.
| | - Biao Yu
- School of Chemistry and Materials Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou 310024, China.
- State Key Laboratory of Chemical Biology, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
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2
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Dhakal B, Mandhapati A, Park S, Sun L, Chaikof EL. Insights Derived from the Synthesis of a Complex Core 2 Glycan. J Org Chem 2024; 89:11641-11658. [PMID: 39087956 DOI: 10.1021/acs.joc.4c01345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/02/2024]
Abstract
We describe the synthesis of a benzoyl-based C2-O-sLeX-Thr-COOH building block devoid of any aglycone transfer or orthoester-formed byproducts. The absence of byproducts was achieved in the course of both [1 + 1] glycosylation reactions with thiophenol aglycone containing galactose acceptors, as well as a [2 + 2] glycosylation in the presence of a p-methoxy benzyl containing glucosamine-fucose disaccharide. We also report an efficient [2 + 1 + 1] synthesis of a peracetylated sLeX en route to a peracetylated C2-O-sLeX-Thr-COOH. While the total synthesis of the latter compound was recently reported by a related route, the divergent [2 + 1 + 1] synthesis provided good reaction yields for each step of the sequence, establishing this scheme as an alternate approach to the peracetylated C2-O-sLeX-Thr-COOH. Importantly, the current report details the role of a variety of hydroxy-protecting groups, including acetyl, benzoyl, p-methoxy benzyl, and naphthylmethyl that may be considered in designing a route to this complex Core 2 glycan. While we have previously described the use of more glycosylation-friendly naphthylmethyl protecting groups, the current synthesis used p-methoxy benzyl protecting groups with excellent reaction yields, demonstrating the feasibility of applying this side reaction-prone protecting group for this challenging synthesis.
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Affiliation(s)
- Bibek Dhakal
- Department of Surgery, Harvard Medical School, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02215, United States
| | - Appi Mandhapati
- Department of Surgery, Harvard Medical School, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02215, United States
| | - Simon Park
- Department of Surgery, Harvard Medical School, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02215, United States
| | - Lijun Sun
- Department of Surgery, Harvard Medical School, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02215, United States
- Harvard Medical School Center for Glycoscience, Harvard Medical School, Boston, Massachusetts 02215, United States
| | - Elliot L Chaikof
- Department of Surgery, Harvard Medical School, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02215, United States
- Harvard Medical School Center for Glycoscience, Harvard Medical School, Boston, Massachusetts 02215, United States
- Wyss Institute of Biologically Inspired Engineering, Harvard University, Boston, Massachusetts 02115, United States
- Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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3
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Sanda M, Yang Q, Zong G, Chen H, Zheng Z, Dhani H, Khan K, Kroemer A, Wang LX, Goldman R. LC-MS/MS-PRM Quantification of IgG Glycoforms Using Stable Isotope Labeled IgG1 Fc Glycopeptide Standard. J Proteome Res 2023; 22:1138-1147. [PMID: 36763792 PMCID: PMC10461028 DOI: 10.1021/acs.jproteome.2c00475] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Indexed: 02/12/2023]
Abstract
Targeted quantification of proteins is a standard methodology with broad utility, but targeted quantification of glycoproteins has not reached its full potential. The lack of optimized workflows and isotopically labeled standards limits the acceptance of glycoproteomics quantification. In this work, we introduce an efficient and streamlined chemoenzymatic synthesis of a library of isotopically labeled glycopeptides of IgG1 which we use for quantification in an energy optimized LC-MS/MS-PRM workflow. Incorporation of the stable isotope labeled N-acetylglucosamine enables an efficient monitoring of all major fragment ions of the glycopeptides generated under the soft higher-energy C-trap dissociation (HCD) conditions, which reduces the coefficients of variability (CVs) of the quantification to 0.7-2.8%. Our results document, for the first time, that the workflow using a combination of stable isotope labeled standards with intrascan normalization enables quantification of the glycopeptides by an electron transfer dissociation (ETD) workflow, as well as the HCD workflow, with the highest sensitivity compared to traditional workflows. This was exemplified by a rapid quantification (13 min) of IgG1 Fc glycoforms from COVID-19 patients.
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Affiliation(s)
- Miloslav Sanda
- Department
of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, D.C. 20057, United States
- Clinical
and Translational Glycoscience Research Center, Georgetown University, Washington, D.C. 20057, United States
- Max-Planck-Institut
fuer Herz- und Lungenforschung, Ludwigstrasse 43, Bad Nauheim, 61231, Germany
| | - Qiang Yang
- GlycoT Therapeutics, College Park, Maryland 20742, United States
| | - Guanghui Zong
- Department
of Chemistry and Biochemistry, University
of Maryland, College
Park, Maryland 20742, United States
| | - He Chen
- GlycoT Therapeutics, College Park, Maryland 20742, United States
| | - Zhihao Zheng
- GlycoT Therapeutics, College Park, Maryland 20742, United States
| | - Harmeet Dhani
- MedStar Georgetown
Transplant Institute, MedStar Georgetown University Hospital and the
Center for Translational Transplant Medicine, Georgetown University Medical Center, Washington, D.C. 20057, United States
| | - Khalid Khan
- MedStar Georgetown
Transplant Institute, MedStar Georgetown University Hospital and the
Center for Translational Transplant Medicine, Georgetown University Medical Center, Washington, D.C. 20057, United States
| | - Alexander Kroemer
- MedStar Georgetown
Transplant Institute, MedStar Georgetown University Hospital and the
Center for Translational Transplant Medicine, Georgetown University Medical Center, Washington, D.C. 20057, United States
| | - Lai-Xi Wang
- Department
of Chemistry and Biochemistry, University
of Maryland, College
Park, Maryland 20742, United States
| | - Radoslav Goldman
- Department
of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, D.C. 20057, United States
- Clinical
and Translational Glycoscience Research Center, Georgetown University, Washington, D.C. 20057, United States
- Department
of Biochemistry and Molecular & Cell Biology, Georgetown University, Washington, D.C. 20057, United States
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4
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Sanda M, Yang Q, Zong G, Chen H, Zheng Z, Dhani H, Khan K, Kroemer A, Wang LX, Goldman R. LC-MS/MS-PRM Quantification of IgG glycoforms using stable isotope labeled IgG1 Fc glycopeptide standard. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2022:2022.08.02.501850. [PMID: 35982648 PMCID: PMC9387126 DOI: 10.1101/2022.08.02.501850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Targeted quantification of proteins is a standard methodology with broad utility, but targeted quantification of glycoproteins has not reached its full potential. The lack of optimized workflows and isotopically labeled standards limits the acceptance of glycoproteomics quantification. In this paper, we introduce an efficient and streamlined chemoenzymatic synthesis of a library of isotopically labeled glycopeptides of IgG1 which we use for quantification in an energy optimized LC-MS/MS-PRM workflow. Incorporation of the stable isotope labeled N-acetylglucosamine enables an efficient monitoring of all major fragment ions of the glycopeptides generated under the soft collision induced dissociation (CID) conditions which reduces the CVs of the quantification to 0.7-2.8%. Our results document, for the first time, that the workflow using a combination of stable isotope labeled standards with intra-scan normalization enables quantification of the glycopeptides by an electron transfer dissociation (ETD) workflow as well as the CID workflow with the highest sensitivity compared to traditional workflows., This was exemplified by a rapid quantification (13-minute) of IgG1 Fc glycoforms from COVID-19 patients. Graphic Abstract
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Harvey DJ. ANALYSIS OF CARBOHYDRATES AND GLYCOCONJUGATES BY MATRIX-ASSISTED LASER DESORPTION/IONIZATION MASS SPECTROMETRY: AN UPDATE FOR 2015-2016. MASS SPECTROMETRY REVIEWS 2021; 40:408-565. [PMID: 33725404 DOI: 10.1002/mas.21651] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 07/24/2020] [Indexed: 06/12/2023]
Abstract
This review is the ninth update of the original article published in 1999 on the application of matrix-assisted laser desorption/ionization (MALDI) mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2016. Also included are papers that describe methods appropriate to analysis by MALDI, such as sample preparation techniques, even though the ionization method is not MALDI. Topics covered in the first part of the review include general aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, fragmentation and arrays. The second part of the review is devoted to applications to various structural types such as oligo- and poly-saccharides, glycoproteins, glycolipids, glycosides and biopharmaceuticals. Much of this material is presented in tabular form. The third part of the review covers medical and industrial applications of the technique, studies of enzyme reactions and applications to chemical synthesis. The reported work shows increasing use of combined new techniques such as ion mobility and the enormous impact that MALDI imaging is having. MALDI, although invented over 30 years ago is still an ideal technique for carbohydrate analysis and advancements in the technique and range of applications show no sign of deminishing. © 2020 Wiley Periodicals, Inc.
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Affiliation(s)
- David J Harvey
- Nuffield Department of Medicine, Target Discovery Institute, University of Oxford, Roosevelt Drive, Oxford, OX3 7FZ, United Kingdom
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6
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Verpalen ECJM, Brouwer AJ, Boons GJ. Synthesis of monophosphoryl lipid A using 2-naphtylmethyl ethers as permanent protecting groups. Carbohydr Res 2020; 498:108152. [PMID: 33032087 DOI: 10.1016/j.carres.2020.108152] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 09/07/2020] [Accepted: 09/09/2020] [Indexed: 11/18/2022]
Abstract
Lipid A, which is a conserved component of lipopolysaccharides of gram-negative bacteria, has attracted considerable interest for the development of immuno-adjuvants. Most approaches for lipid A synthesis rely on the use of benzyl ethers as permanent protecting groups. Due to the amphiphilic character of lipid A, these compounds aggregate during the hydrogenation step to remove benzyl ethers, resulting in a sluggish reaction and by-product formation. To address this problem, we have developed a synthetic approach based on the use of 2-naphtylmethyl ether (Nap) ethers as permanent protecting group for hydroxyls. At the end of a synthetic sequence, multiple of these protecting groups can readily be removed by oxidation with 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ). Di-allyl N,N-diisopropylphosphoramidite was employed to install the phosphate ester and the resulting allyl esters were cleaved using palladium tetrakistriphenylphosphine. The synthetic strategy allows late stage introduction of different fatty acids at the amines of the target compound, which is facilitated by Troc and Fmoc as orthogonal amino-protecting groups.
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Affiliation(s)
- Enrico C J M Verpalen
- Department of Chemical Biology and Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, and Bijvoet Center for Biomolecular Research, Utrecht University, Universiteitsweg 99, Utrecht 3584 CG, the Netherlands
| | - Arwin J Brouwer
- Department of Chemical Biology and Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, and Bijvoet Center for Biomolecular Research, Utrecht University, Universiteitsweg 99, Utrecht 3584 CG, the Netherlands
| | - Geert-Jan Boons
- Department of Chemical Biology and Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, and Bijvoet Center for Biomolecular Research, Utrecht University, Universiteitsweg 99, Utrecht 3584 CG, the Netherlands; Complex Carbohydrate Research Center and Department of Chemistry, University of Georgia, Athens, GA 30602, USA.
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7
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Mandalasi M, Kim HW, Thieker D, Sheikh MO, Gas-Pascual E, Rahman K, Zhao P, Daniel NG, van der Wel H, Ichikawa HT, Glushka JN, Wells L, Woods RJ, Wood ZA, West CM. A terminal α3-galactose modification regulates an E3 ubiquitin ligase subunit in Toxoplasma gondii. J Biol Chem 2020; 295:9223-9243. [PMID: 32414843 PMCID: PMC7335778 DOI: 10.1074/jbc.ra120.013792] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Revised: 05/14/2020] [Indexed: 12/29/2022] Open
Abstract
Skp1, a subunit of E3 Skp1/Cullin-1/F-box protein ubiquitin ligases, is modified by a prolyl hydroxylase that mediates O2 regulation of the social amoeba Dictyostelium and the parasite Toxoplasma gondii The full effect of hydroxylation requires modification of the hydroxyproline by a pentasaccharide that, in Dictyostelium, influences Skp1 structure to favor assembly of Skp1/F-box protein subcomplexes. In Toxoplasma, the presence of a contrasting penultimate sugar assembled by a different glycosyltransferase enables testing of the conformational control model. To define the final sugar and its linkage, here we identified the glycosyltransferase that completes the glycan and found that it is closely related to glycogenin, an enzyme that may prime glycogen synthesis in yeast and animals. However, the Toxoplasma enzyme catalyzes formation of a Galα1,3Glcα linkage rather than the Glcα1,4Glcα linkage formed by glycogenin. Kinetic and crystallographic experiments showed that the glycosyltransferase Gat1 is specific for Skp1 in Toxoplasma and also in another protist, the crop pathogen Pythium ultimum The fifth sugar is important for glycan function as indicated by the slow-growth phenotype of gat1Δ parasites. Computational analyses indicated that, despite the sequence difference, the Toxoplasma glycan still assumes an ordered conformation that controls Skp1 structure and revealed the importance of nonpolar packing interactions of the fifth sugar. The substitution of glycosyltransferases in Toxoplasma and Pythium by an unrelated bifunctional enzyme that assembles a distinct but structurally compatible glycan in Dictyostelium is a remarkable case of convergent evolution, which emphasizes the importance of the terminal α-galactose and establishes the phylogenetic breadth of Skp1 glycoregulation.
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Affiliation(s)
- Msano Mandalasi
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, USA; Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, USA
| | - Hyun W Kim
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, USA
| | - David Thieker
- Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia, USA
| | - M Osman Sheikh
- Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia, USA
| | - Elisabet Gas-Pascual
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, USA; Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, USA
| | - Kazi Rahman
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, USA
| | - Peng Zhao
- Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia, USA
| | - Nitin G Daniel
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, USA
| | - Hanke van der Wel
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, USA
| | - H Travis Ichikawa
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, USA
| | - John N Glushka
- Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia, USA
| | - Lance Wells
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, USA; Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia, USA
| | - Robert J Woods
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, USA; Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia, USA
| | - Zachary A Wood
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, USA
| | - Christopher M West
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, USA; Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, USA; Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia, USA.
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8
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Sheikh MO, Thieker D, Chalmers G, Schafer CM, Ishihara M, Azadi P, Woods RJ, Glushka JN, Bendiak B, Prestegard JH, West CM. O 2 sensing-associated glycosylation exposes the F-box-combining site of the Dictyostelium Skp1 subunit in E3 ubiquitin ligases. J Biol Chem 2017; 292:18897-18915. [PMID: 28928219 PMCID: PMC5704474 DOI: 10.1074/jbc.m117.809160] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 09/12/2017] [Indexed: 11/06/2022] Open
Abstract
Skp1 is a conserved protein linking cullin-1 to F-box proteins in SCF (Skp1/Cullin-1/F-box protein) E3 ubiquitin ligases, which modify protein substrates with polyubiquitin chains that typically target them for 26S proteasome-mediated degradation. In Dictyostelium (a social amoeba), Toxoplasma gondii (the agent for human toxoplasmosis), and other protists, Skp1 is regulated by a unique pentasaccharide attached to hydroxylated Pro-143 within its C-terminal F-box-binding domain. Prolyl hydroxylation of Skp1 contributes to O2-dependent Dictyostelium development, but full glycosylation at that position is required for optimal O2 sensing. Previous studies have shown that the glycan promotes organization of the F-box-binding region in Skp1 and aids in Skp1's association with F-box proteins. Here, NMR and MS approaches were used to determine the glycan structure, and then a combination of NMR and molecular dynamics simulations were employed to characterize the impact of the glycan on the conformation and motions of the intrinsically flexible F-box-binding domain of Skp1. Molecular dynamics trajectories of glycosylated Skp1 whose calculated monosaccharide relaxation kinetics and rotational correlation times agreed with the NMR data indicated that the glycan interacts with the loop connecting two α-helices of the F-box-combining site. In these trajectories, the helices separated from one another to create a more accessible and dynamic F-box interface. These results offer an unprecedented view of how a glycan modification influences a disordered region of a full-length protein. The increased sampling of an open Skp1 conformation can explain how glycosylation enhances interactions with F-box proteins in cells.
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Affiliation(s)
- M Osman Sheikh
- From the Department of Biochemistry and Molecular Biology
- the Complex Carbohydrate Research Center, and
- the Department of Biochemistry and Molecular Biology, Oklahoma Center for Medical Glycobiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, and
| | | | - Gordon Chalmers
- the Complex Carbohydrate Research Center, and
- the Department of Computer Science, University of Georgia, Athens, Georgia 30602
| | - Christopher M Schafer
- the Department of Biochemistry and Molecular Biology, Oklahoma Center for Medical Glycobiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, and
| | | | | | - Robert J Woods
- From the Department of Biochemistry and Molecular Biology
- the Complex Carbohydrate Research Center, and
| | | | - Brad Bendiak
- the Department of Cell and Developmental Biology, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045
| | - James H Prestegard
- From the Department of Biochemistry and Molecular Biology
- the Complex Carbohydrate Research Center, and
| | - Christopher M West
- From the Department of Biochemistry and Molecular Biology,
- the Department of Biochemistry and Molecular Biology, Oklahoma Center for Medical Glycobiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, and
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9
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Rahman K, Mandalasi M, Zhao P, Sheikh MO, Taujale R, Kim HW, van der Wel H, Matta K, Kannan N, Glushka JN, Wells L, West CM. Characterization of a cytoplasmic glucosyltransferase that extends the core trisaccharide of the Toxoplasma Skp1 E3 ubiquitin ligase subunit. J Biol Chem 2017; 292:18644-18659. [PMID: 28928220 DOI: 10.1074/jbc.m117.809301] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 09/12/2017] [Indexed: 01/06/2023] Open
Abstract
Skp1 is a subunit of the SCF (Skp1/Cullin 1/F-box protein) class of E3 ubiquitin ligases that are important for eukaryotic protein degradation. Unlike its animal counterparts, Skp1 from Toxoplasma gondii is hydroxylated by an O2-dependent prolyl-4-hydroxylase (PhyA), and the resulting hydroxyproline can subsequently be modified by a five-sugar chain. A similar modification is found in the social amoeba Dictyostelium, where it regulates SCF assembly and O2-dependent development. Homologous glycosyltransferases assemble a similar core trisaccharide in both organisms, and a bifunctional α-galactosyltransferase from CAZy family GT77 mediates the addition of the final two sugars in Dictyostelium, generating Galα1, 3Galα1,3Fucα1,2Galβ1,3GlcNAcα1-. Here, we found that Toxoplasma utilizes a cytoplasmic glycosyltransferase from an ancient clade of CAZy family GT32 to catalyze transfer of the fourth sugar. Catalytically active Glt1 was required for the addition of the terminal disaccharide in cells, and cytosolic extracts catalyzed transfer of [3H]glucose from UDP-[3H]glucose to the trisaccharide form of Skp1 in a glt1-dependent fashion. Recombinant Glt1 catalyzed the same reaction, confirming that it directly mediates Skp1 glucosylation, and NMR demonstrated formation of a Glcα1,3Fuc linkage. Recombinant Glt1 strongly preferred the full core trisaccharide attached to Skp1 and labeled only Skp1 in glt1Δ extracts, suggesting specificity for Skp1. glt1-knock-out parasites exhibited a growth defect not rescued by catalytically inactive Glt1, indicating that the glycan acts in concert with the first enzyme in the pathway, PhyA, in cells. A genomic bioinformatics survey suggested that Glt1 belongs to the ancestral Skp1 glycosylation pathway in protists and evolved separately from related Golgi-resident GT32 glycosyltransferases.
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Affiliation(s)
- Kazi Rahman
- From the Department of Biochemistry and Molecular Biology.,the Departments of Microbiology and Immunology and
| | - Msano Mandalasi
- From the Department of Biochemistry and Molecular Biology.,Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, and
| | - Peng Zhao
- the Complex Carbohydrate Research Center, and
| | | | - Rahil Taujale
- the Complex Carbohydrate Research Center, and.,the Institute of Bioinformatics, University of Georgia, Athens, Georgia 30602
| | - Hyun W Kim
- From the Department of Biochemistry and Molecular Biology
| | | | - Khushi Matta
- the Department of Chemical and Biological Engineering, State University of New York, Buffalo, New York 14260
| | - Natarajan Kannan
- From the Department of Biochemistry and Molecular Biology.,the Institute of Bioinformatics, University of Georgia, Athens, Georgia 30602
| | | | - Lance Wells
- From the Department of Biochemistry and Molecular Biology.,the Complex Carbohydrate Research Center, and
| | - Christopher M West
- From the Department of Biochemistry and Molecular Biology, .,Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, and
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