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Comparative studies on the substrate specificity and defucosylation activity of three α-l-fucosidases using synthetic fucosylated glycopeptides and glycoproteins as substrates. Bioorg Med Chem 2021; 42:116243. [PMID: 34126284 DOI: 10.1016/j.bmc.2021.116243] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 05/24/2021] [Accepted: 05/25/2021] [Indexed: 11/24/2022]
Abstract
Core fucosylation is the attachment of an α-1,6-fucose moiety to the innermost N-acetyl glucosamine (GlcNAc) in N-glycans in mammalian systems. It plays a pivotal role in modulating the structural and biological functions of glycoproteins including therapeutic antibodies. Yet, few α-l-fucosidases appear to be capable of removing core fucose from intact glycoproteins. This paper describes a comparative study of the substrate specificity and relative activity of the human α-l-fucosidase (FucA1) and two bacterial α-l-fucosidases, the AlfC from Lactobacillus casei and the BfFuc from Bacteroides fragilis. This study was enabled by the synthesis of an array of structurally well-defined core-fucosylated substrates, including core-fucosylated N-glycopeptides and a few antibody glycoforms. It was found that AlfC and BfFuc could not remove core fucose from intact full-length N-glycopeptides or N-glycoproteins but could hydrolyze only the truncated Fucα1,6GlcNAc-peptide substrates. In contrast, the human α-l-fucosidase (FucA1) showed low activity on truncated Fucα1,6GlcNAc substrates but was able to remove core fucose from intact and full-length core-fucosylated N-glycopeptides and N-glycoproteins. In addition, it was found that FucA1 was the only α-l-fucosidase that showed low but apparent activity to remove core fucose from intact IgG antibodies. The ability of FucA1 to defucosylate intact monoclonal antibodies reveals an opportunity to evolve the human α-l-fucosidase for direct enzymatic defucosylation of therapeutic antibodies to improve their antibody-dependent cellular cytotoxicity.
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2
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Zhang R, Yang Q, Boruah BM, Zong G, Li C, Chapla D, Yang JY, Moremen KW, Wang LX. Appropriate aglycone modification significantly expands the glycan substrate acceptability of α1,6-fucosyltransferase (FUT8). Biochem J 2021; 478:1571-1583. [PMID: 33734311 PMCID: PMC8062310 DOI: 10.1042/bcj20210138] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 03/17/2021] [Accepted: 03/17/2021] [Indexed: 12/16/2022]
Abstract
The α1,6-fucosyltransferase, FUT8, is the sole enzyme catalyzing the core-fucosylation of N-glycoproteins in mammalian systems. Previous studies using free N-glycans as acceptor substrates indicated that a terminal β1,2-GlcNAc moiety on the Man-α1,3-Man arm of N-glycan substrates is required for efficient FUT8-catalyzed core-fucosylation. In contrast, we recently demonstrated that, in a proper protein context, FUT8 could also fucosylate Man5GlcNAc2 without a GlcNAc at the non-reducing end. We describe here a further study of the substrate specificity of FUT8 using a range of N-glycans containing different aglycones. We found that FUT8 could fucosylate most of high-mannose and complex-type N-glycans, including highly branched N-glycans from chicken ovalbumin, when the aglycone moiety is modified with a 9-fluorenylmethyloxycarbonyl (Fmoc) moiety or in a suitable peptide/protein context, even if they lack the terminal GlcNAc moiety on the Man-α1,3-Man arm. FUT8 could also fucosylate paucimannose structures when they are on glycoprotein substrates. Such core-fucosylated paucimannosylation is a prominent feature of lysosomal proteins of human neutrophils and several types of cancers. We also found that sialylation of N-glycans significantly reduced their activity as a substrate of FUT8. Kinetic analysis demonstrated that Fmoc aglycone modification could either improve the turnover rate or decrease the KM value depending on the nature of the substrates, thus significantly enhancing the overall efficiency of FUT8 catalyzed fucosylation. Our results indicate that an appropriate aglycone context of N-glycans could significantly broaden the acceptor substrate specificity of FUT8 beyond what has previously been thought.
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Affiliation(s)
- Roushu Zhang
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742
| | - Qiang Yang
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742
| | - Bhargavi M Boruah
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602
| | - Guanghui Zong
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742
| | - Chao Li
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742
| | - Digantkumar Chapla
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602
| | - Jeong-Yeh Yang
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602
| | - Kelley W Moremen
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602
| | - Lai-Xi Wang
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742
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3
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Yang Q, Zhang R, Cai H, Wang LX. Revisiting the substrate specificity of mammalian α1,6-fucosyltransferase reveals that it catalyzes core fucosylation of N-glycans lacking α1,3-arm GlcNAc. J Biol Chem 2017; 292:14796-14803. [PMID: 28729420 DOI: 10.1074/jbc.m117.804070] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 07/17/2017] [Indexed: 01/21/2023] Open
Abstract
The mammalian α1,6-fucosyltransferase (FUT8) catalyzes the core fucosylation of N-glycans in the biosynthesis of glycoproteins. Previously, intensive in vitro studies with crude extract or purified enzyme concluded that the attachment of a GlcNAc on the α1,3 mannose arm of N-glycan is essential for FUT8-catalyzed core fucosylation. In contrast, we have recently shown that expression of erythropoietin in a GnTI knock-out, FUT8-overexpressing cell line results in the production of fully core-fucosylated glycoforms of the oligomannose substrate Man5GlcNAc2, suggesting that FUT8 can catalyze core fucosylation of N-glycans lacking an α1,3-arm GlcNAc in cells. Here, we revisited the substrate specificity of FUT8 by examining its in vitro activity toward an array of selected N-glycans, glycopeptides, and glycoproteins. Consistent with previous studies, we found that free N-glycans lacking an unmasked α1,3-arm GlcNAc moiety are not FUT8 substrates. However, Man5GlcNAc2 glycan could be efficiently core-fucosylated by FUT8 in an appropriate protein/peptide context, such as with the erythropoietin protein, a V3 polypeptide derived from HIV-1 gp120, or a simple 9-fluorenylmethyl chloroformate-protected Asn moiety. Interestingly, when placed in the V3 polypeptide context, a mature bi-antennary complex-type N-glycan also could be core-fucosylated by FUT8, albeit at much lower efficiency than the Man5GlcNAc2 peptide. This study represents the first report of in vitro FUT8-catalyzed core fucosylation of N-glycans lacking the α1,3-arm GlcNAc moiety. Our results suggest that an appropriate polypeptide context or other adequate structural elements in the acceptor substrate could facilitate the core fucosylation by FUT8.
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Affiliation(s)
- Qiang Yang
- From the Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742
| | - Roushu Zhang
- From the Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742
| | - Hui Cai
- From the Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742
| | - Lai-Xi Wang
- From the Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742
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4
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Abstract
N-glycosylation plays important roles in modulating the biological functions of glycoproteins, such as protein folding, stability, and immunogenicity. However, acquiring homogeneous glycoforms of glycoproteins has been a challenging task for functional studies and therapeutic applications. In this chapter, we describe an efficient chemoenzymatic glycan remodeling protocol for making homogeneous glycoproteins that involves enzymatic deglycosylation and subsequent reglycosylation procedures. Two therapeutic glycoproteins, Herceptin (trastuzumab, a therapeutic monoclonal antibody) and erythropoietin (EPO, a glycoprotein hormone), were chosen as the model systems. The detailed protocol includes the deglycosylation of the Herceptin or EPO with a wild-type endo-β-N-acetylglucosaminidase, to remove the heterogeneous N-glycans, leading to the GlcNAc-protein or Fucα1,6GlcNAc-protein intermediate. Then desired homogeneous N-glycans are attached to the acceptor by using an activated sugar oxazoline as the donor substrate and a specific glycosynthase (mutant of endoglycosidase) as the catalyst to reconstitute a homogeneous glycoform. Using this approach, Herceptin was remodeled to an afucosylated complex glycoform and a Man9GlcNAc2 glycoform, with the former showing significantly enhanced antibody-dependent cellular cytotoxicity. EPO was engineered to carry azide-tagged Man3GlcNAc2 glycans that could be further modified via click chemistry to introduce other functional groups.
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5
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Yang Q, An Y, Zhu S, Zhang R, Loke CM, Cipollo JF, Wang LX. Glycan Remodeling of Human Erythropoietin (EPO) Through Combined Mammalian Cell Engineering and Chemoenzymatic Transglycosylation. ACS Chem Biol 2017; 12:1665-1673. [PMID: 28452462 DOI: 10.1021/acschembio.7b00282] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The tremendous structural heterogeneity of N-glycosylation of glycoproteins poses a great challenge for deciphering the biological functions of specific glycoforms and for developing protein-based therapeutics. We have previously reported a chemoenzymatic glycan remodeling method for producing homogeneous glycoforms of N-glycoproteins including intact antibodies, which consist of endoglycosidase-catalyzed deglycosylation and novel glycosynthase-catalyzed transglycosylation, but its application to complex glycoproteins carrying multiple N-glycans remains to be examined. We report here site-selective chemoenzymatic glycosylation remodeling of recombinant human erythropoietin (EPO) that contains three N-glycans. We found that the generation of a HEK293S GnT I knockout FUT8 overexpressing cell line enabled the production of an unusual Man5GlcNAc2Fuc glycoform, which could be converted to the core-fucosylated GlcNAc-EPO intermediate acceptor for enzymatic transglycosylation. With this acceptor, homogeneous sialylated glycoform or azide-tagged glycoform were produced using the glycosynthase (EndoF3-D165A) catalyzed transglycosylation. Interestingly, a remarkable site-selectivity was observed in the transglycosylation reactions, leading to the introduction of two N-glycans selectively at the Asn-38 and Asn-83 sites, which was confirmed by a detailed MS/MS analysis of the transglycosylation product. Finally, a different N-glycan was attached at the third (Asn-24) site by pushing the enzymatic transglycosylation with a distinct glycan oxazoline, achieving the site-selective glycosylation modification of the protein. This study represents the first example of site-selective chemoenzymatic glycan engineering of complex glycoproteins carrying multiple N-glycans.
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Affiliation(s)
- Qiang Yang
- Department
of Chemistry and Biochemistry, University of Maryland, College
Park, Maryland 20742, United States
| | - Yanming An
- Center for Biologics
Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland 20993, United States
| | - Shilei Zhu
- Department
of Chemistry and Biochemistry, University of Maryland, College
Park, Maryland 20742, United States
| | - Roushu Zhang
- Department
of Chemistry and Biochemistry, University of Maryland, College
Park, Maryland 20742, United States
| | - Chun Mun Loke
- Department
of Chemistry and Biochemistry, University of Maryland, College
Park, Maryland 20742, United States
| | - John F. Cipollo
- Center for Biologics
Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland 20993, United States
| | - Lai-Xi Wang
- Department
of Chemistry and Biochemistry, University of Maryland, College
Park, Maryland 20742, United States
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6
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Chen W, Kong L, Connelly S, Dendle JM, Liu Y, Wilson IA, Powers ET, Kelly JW. Stabilizing the CH2 Domain of an Antibody by Engineering in an Enhanced Aromatic Sequon. ACS Chem Biol 2016; 11:1852-61. [PMID: 27128252 DOI: 10.1021/acschembio.5b01035] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Monoclonal antibodies (mAbs) exhibiting highly selective binding to a protein target constitute a large and growing proportion of the therapeutics market. Aggregation of mAbs results in the loss of their therapeutic efficacy and can result in deleterious immune responses. The CH2 domain comprising part of the Fc portion of Immunoglobulin G (IgG) is typically the least stable domain in IgG-type antibodies and therefore influences their aggregation propensity. We stabilized the CH2 domain by engineering an enhanced aromatic sequon (EAS) into the N-glycosylated C'E loop and observed a 4.8 °C increase in the melting temperature of the purified IgG1 Fc fragment. This EAS-stabilized CH2 domain also conferred enhanced stability against thermal and low pH induced aggregation in the context of a full-length monoclonal IgG1 antibody. The crystal structure of the EAS-stabilized (Q295F/Y296A) IgG1 Fc fragment confirms the design principle, i.e., the importance of the GlcNAc1•F295 interaction, and surprisingly reveals that the core fucose attached to GlcNAc1 also engages in an interaction with F295. Inhibition of core fucosylation confirms the contribution of the fucose-Phe interaction to the stabilization. The Q295F/Y296A mutations also modulate the binding affinity of the full-length antibody to Fc receptors by decreasing the binding to low affinity Fc gamma receptors (FcγRIIa, FcγRIIIa, and FcγRIIIb), while maintaining wild-type binding affinity to FcRn and FcγRI. Our results demonstrate that engineering an EAS into the N-glycosylated reverse turn on the C'E loop leads to stabilizing N-glycan-protein interactions in antibodies and that this modification modulates antibody-Fc receptor binding.
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Affiliation(s)
- Wentao Chen
- Department
of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California 92037, United States
- Department
of Chemistry, The Scripps Research Institute, La Jolla, California 92037, United States
| | - Leopold Kong
- Department
of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California 92037, United States
| | - Stephen Connelly
- Department
of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California 92037, United States
| | - Julia M. Dendle
- Department
of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California 92037, United States
- Department
of Chemistry, The Scripps Research Institute, La Jolla, California 92037, United States
| | - Yu Liu
- Department
of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California 92037, United States
- Department
of Chemistry, The Scripps Research Institute, La Jolla, California 92037, United States
| | - Ian A. Wilson
- Department
of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California 92037, United States
- The
Skaggs Institute for Chemical Biology, The Scripps Research Institute, La
Jolla, California 92037, United States
| | - Evan T. Powers
- Department
of Chemistry, The Scripps Research Institute, La Jolla, California 92037, United States
| | - Jeffery W. Kelly
- Department
of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California 92037, United States
- Department
of Chemistry, The Scripps Research Institute, La Jolla, California 92037, United States
- The
Skaggs Institute for Chemical Biology, The Scripps Research Institute, La
Jolla, California 92037, United States
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7
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Wang Z, Qin C, Hu J, Guo X, Yin J. Recent advances in synthetic carbohydrate-based human immunodeficiency virus vaccines. Virol Sin 2016; 31:110-7. [PMID: 26992403 DOI: 10.1007/s12250-015-3691-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 03/02/2016] [Indexed: 12/14/2022] Open
Abstract
An effective vaccine for human immunodeficiency virus (HIV) is urgently needed to prevent HIV infection and progression to acquired immune deficiency syndrome (AIDS). As glycosylation of viral proteins becomes better understood, carbohydrate-based antiviral vaccines against special viruses have attracted much attention. Significant efforts in carbohydrate synthesis and immunogenicity research have resulted in the development of multiple carbohydrate-based HIV vaccines. This review summarizes recent advances in synthetic carbohydrate-based vaccines design strategies and the applications of these vaccines in the prevention of HIV.
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Affiliation(s)
- Zhenyuan Wang
- Key Laboratory of Carbohydrate Chemistry and Biotechnology Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China
| | - Chunjun Qin
- Key Laboratory of Carbohydrate Chemistry and Biotechnology Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China
| | - Jing Hu
- Key Laboratory of Carbohydrate Chemistry and Biotechnology Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China.,Wuxi Medical School, Jiangnan University, Wuxi, 214122, China
| | - Xiaoqiang Guo
- Key Laboratory of Carbohydrate Chemistry and Biotechnology Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China
| | - Jian Yin
- Key Laboratory of Carbohydrate Chemistry and Biotechnology Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China.
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8
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Murine Antibody Responses to Cleaved Soluble HIV-1 Envelope Trimers Are Highly Restricted in Specificity. J Virol 2015; 89:10383-98. [PMID: 26246566 DOI: 10.1128/jvi.01653-15] [Citation(s) in RCA: 129] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 07/28/2015] [Indexed: 01/01/2023] Open
Abstract
UNLABELLED Generating neutralizing antibodies (nAbs) is a major goal of many current HIV-1 vaccine efforts. To be of practical value, these nAbs must be both potent and cross-reactive in order to be capable of preventing the transmission of the highly diverse and generally neutralization resistant (Tier-2) HIV-1 strains that are in circulation. The HIV-1 envelope glycoprotein (Env) spike is the only target for nAbs. To explore whether Tier-2 nAbs can be induced by Env proteins, we immunized conventional mice with soluble BG505 SOSIP.664 trimers that mimic the native Env spike. Here, we report that it is extremely difficult for murine B cells to recognize the Env epitopes necessary for inducing Tier-2 nAbs. Thus, while trimer-immunized mice raised Env-binding IgG Abs and had high-quality T follicular helper (Tfh) cell and germinal center (GC) responses, they did not make BG505.T332N nAbs. Epitope mapping studies showed that Ab responses in mice were specific to areas near the base of the soluble trimer. These areas are not well shielded by glycans and likely are occluded on virions, which is consistent with the lack of BG505.T332N nAbs. These data inform immunogen design and suggest that it is useful to obscure nonneutralizing epitopes presented on the base of soluble Env trimers and that the glycan shield of well-formed HIV Env trimers is virtually impenetrable for murine B cell receptors (BCRs). IMPORTANCE Human HIV vaccine efficacy trials have not generated meaningful neutralizing antibodies to circulating HIV strains. One possible hindrance has been the lack of immunogens that properly mimic the native conformation of the HIV envelope trimer protein. Here, we tested the first generation of soluble, native-like envelope trimer immunogens in a conventional mouse model. We attempted to generate neutralizing antibodies to neutralization-resistant circulating HIV strains. Various vaccine strategies failed to induce neutralizing antibodies to a neutralization-resistant HIV strain. Further analysis revealed that mouse antibodies targeted areas near the bottom of the soluble envelope trimers. These areas are not easily accessible on the HIV virion due to occlusion by the viral membrane and may have resulted from an absence of glycan shielding. Our results suggest that obscuring the bottom of soluble envelope trimers is a useful strategy to reduce antibody responses to epitopes that are not useful for virus neutralization.
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Harvey DJ. Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: an update for 2009-2010. MASS SPECTROMETRY REVIEWS 2015; 34:268-422. [PMID: 24863367 PMCID: PMC7168572 DOI: 10.1002/mas.21411] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 07/16/2013] [Accepted: 07/16/2013] [Indexed: 05/07/2023]
Abstract
This review is the sixth update of the original article published in 1999 on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2010. General aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, arrays and fragmentation are covered in the first part of the review and applications to various structural typed constitutes the remainder. The main groups of compound that are discussed in this section are oligo and polysaccharides, glycoproteins, glycolipids, glycosides and biopharmaceuticals. Many of these applications are presented in tabular form. Also discussed are medical and industrial applications of the technique, studies of enzyme reactions and applications to chemical synthesis.
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Affiliation(s)
- David J. Harvey
- Department of BiochemistryOxford Glycobiology InstituteUniversity of OxfordOxfordOX1 3QUUK
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10
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Wang D, Tang J, Tang J, Wang LX. Targeting N-glycan cryptic sugar moieties for broad-spectrum virus neutralization: progress in identifying conserved molecular targets in viruses of distinct phylogenetic origins. Molecules 2015; 20:4610-22. [PMID: 25774492 PMCID: PMC4633014 DOI: 10.3390/molecules20034610] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Revised: 02/26/2015] [Accepted: 03/09/2015] [Indexed: 11/16/2022] Open
Abstract
Identifying molecular targets for eliciting broadly virus-neutralizing antibodies is one of the key steps toward development of vaccines against emerging viral pathogens. Owing to genomic and somatic diversities among viral species, identifying protein targets for broad-spectrum virus neutralization is highly challenging even for the same virus, such as HIV-1. However, viruses rely on host glycosylation machineries to synthesize and express glycans and, thereby, may display common carbohydrate moieties. Thus, exploring glycan-binding profiles of broad-spectrum virus-neutralizing agents may provide key information to uncover the carbohydrate-based virus-neutralizing epitopes. In this study, we characterized two broadly HIV-neutralizing agents, human monoclonal antibody 2G12 and Galanthus nivalis lectin (GNA), for their viral targeting activities. Although these agents were known to be specific for oligomannosyl antigens, they differ strikingly in virus-binding activities. The former is HIV-1 specific; the latter is broadly reactive and is able to neutralize viruses of distinct phylogenetic origins, such as HIV-1, severe acute respiratory syndrome coronavirus (SARS-CoV), and human cytomegalovirus (HCMV). In carbohydrate microarray analyses, we explored the molecular basis underlying the striking differences in the spectrum of anti-virus activities of the two probes. Unlike 2G12, which is strictly specific for the high-density Man9GlcNAc2Asn (Man9)-clusters, GNA recognizes a number of N-glycan cryptic sugar moieties. These include not only the known oligomannosyl antigens but also previously unrecognized tri-antennary or multi-valent GlcNAc-terminating N-glycan epitopes (Tri/m-Gn). These findings highlight the potential of N-glycan cryptic sugar moieties as conserved targets for broad-spectrum virus neutralization and suggest the GNA-model of glycan-binding warrants focused investigation.
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Affiliation(s)
- Denong Wang
- Tumor Glycomics Laboratory, SRI International Biosciences Division, Menlo Park, CA 94025, USA.
| | - Jin Tang
- Tumor Glycomics Laboratory, SRI International Biosciences Division, Menlo Park, CA 94025, USA.
| | - Jiulai Tang
- Department of Pediatrics, The First Affiliated Hospital of Anhui Medical University, Hefei 230032, China.
| | - Lai-Xi Wang
- Instituteof Human Virology, Department of Biochemistry & Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
- Department of Chemistry and Biochemistry, University of Maryland at College Park, College Park, MD 20742, USA.
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11
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Horiya S, MacPherson IS, Krauss IJ. Recent strategies targeting HIV glycans in vaccine design. Nat Chem Biol 2014; 10:990-9. [PMID: 25393493 PMCID: PMC4431543 DOI: 10.1038/nchembio.1685] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Accepted: 10/03/2014] [Indexed: 12/20/2022]
Abstract
Although efforts to develop a vaccine against HIV have so far met with little success, recent studies of HIV-positive patients with strongly neutralizing sera have shown that the human immune system is capable of producing potent and broadly neutralizing antibodies (bnAbs), some of which neutralize up to 90% of HIV strains. These antibodies bind conserved vulnerable sites on the viral envelope glycoprotein gp120, and identification of these sites has provided exciting clues about the design of potentially effective vaccines. Carbohydrates have a key role in this field, as a large fraction of bnAbs bind carbohydrates or combinations of carbohydrate and peptide elements on gp120. Additionally, carbohydrates partially mask some peptide surfaces recognized by bnAbs. The use of engineered glycoproteins and other glycostructures as vaccines to elicit antibodies with broad neutralizing activity is therefore a key area of interest in HIV vaccine design.
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Affiliation(s)
- Satoru Horiya
- Department of Chemistry, Brandeis University, Waltham, Massachusetts, USA
| | - Iain S MacPherson
- Department of Chemistry, Brandeis University, Waltham, Massachusetts, USA
| | - Isaac J Krauss
- Department of Chemistry, Brandeis University, Waltham, Massachusetts, USA
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12
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Wu F, Peng K, Tian J, Xu X, Zhou E, Chen H. Immune Response to Fc Tagged GP5 Glycoproteins of Porcine Reproductive and Respiratory Syndrome Virus. Viral Immunol 2014; 27:343-9. [DOI: 10.1089/vim.2014.0041] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Fang Wu
- College of Life Sciences, Northwest A&F University, Yangling, People's Republic of China
| | - Kefeng Peng
- College of Life Sciences, Northwest A&F University, Yangling, People's Republic of China
| | - Jiao Tian
- College of Life Sciences, Northwest A&F University, Yangling, People's Republic of China
| | - Xiaodong Xu
- College of Life Sciences, Northwest A&F University, Yangling, People's Republic of China
| | - Enmin Zhou
- College of Veterinary Medicine, Northwest A&F University, Yangling, People's Republic of China
| | - Hongying Chen
- College of Life Sciences, Northwest A&F University, Yangling, People's Republic of China
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13
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Wood NT, Fadda E, Davis R, Grant OC, Martin JC, Woods RJ, Travers SA. The influence of N-linked glycans on the molecular dynamics of the HIV-1 gp120 V3 loop. PLoS One 2013; 8:e80301. [PMID: 24303005 PMCID: PMC3841175 DOI: 10.1371/journal.pone.0080301] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Accepted: 10/11/2013] [Indexed: 02/07/2023] Open
Abstract
N-linked glycans attached to specific amino acids of the gp120 envelope trimer of a HIV virion can modulate the binding affinity of gp120 to CD4, influence coreceptor tropism, and play an important role in neutralising antibody responses. Because of the challenges associated with crystallising fully glycosylated proteins, most structural investigations have focused on describing the features of a non-glycosylated HIV-1 gp120 protein. Here, we use a computational approach to determine the influence of N-linked glycans on the dynamics of the HIV-1 gp120 protein and, in particular, the V3 loop. We compare the conformational dynamics of a non-glycosylated gp120 structure to that of two glycosylated gp120 structures, one with a single, and a second with five, covalently linked high-mannose glycans. Our findings provide a clear illustration of the significant effect that N-linked glycosylation has on the temporal and spatial properties of the underlying protein structure. We find that glycans surrounding the V3 loop modulate its dynamics, conferring to the loop a marked propensity towards a more narrow conformation relative to its non-glycosylated counterpart. The conformational effect on the V3 loop provides further support for the suggestion that N-linked glycosylation plays a role in determining HIV-1 coreceptor tropism.
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Affiliation(s)
- Natasha T. Wood
- South African National Bioinformatics Institute, South African Medical Research Council Bioinformatics Unit, University of the Western Cape, Cape Town, South Africa
| | - Elisa Fadda
- Department of Chemistry, National University of Ireland, Maynooth, Maynooth, Ireland
| | - Robert Davis
- Complex Carbohydrate Research Centre, University of Georgia, Athens, Georgia, United States of America
| | - Oliver C. Grant
- School of Chemistry, National University of Ireland, Galway, Galway, Ireland
| | - Joanne C. Martin
- School of Chemistry, National University of Ireland, Galway, Galway, Ireland
| | - Robert J. Woods
- Complex Carbohydrate Research Centre, University of Georgia, Athens, Georgia, United States of America
- School of Chemistry, National University of Ireland, Galway, Galway, Ireland
| | - Simon A. Travers
- South African National Bioinformatics Institute, South African Medical Research Council Bioinformatics Unit, University of the Western Cape, Cape Town, South Africa
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14
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MacPherson IS, Temme JS, Habeshian S, Felczak K, Pankiewicz K, Hedstrom L, Krauss IJ. Multivalent glycocluster design through directed evolution. Angew Chem Int Ed Engl 2012; 50:11238-42. [PMID: 22191092 DOI: 10.1002/anie.201105555] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Iain S MacPherson
- Department of Chemistry, Brandeis University, 415 South St., Waltham, MA 02454, USA
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15
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Wang LX, Lomino JV. Emerging technologies for making glycan-defined glycoproteins. ACS Chem Biol 2012; 7:110-22. [PMID: 22141574 DOI: 10.1021/cb200429n] [Citation(s) in RCA: 110] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Protein glycosylation is a common and complex posttranslational modification of proteins, which expands functional diversity while boosting structural heterogeneity. Glycoproteins, the end products of such a modification, are typically produced as mixtures of glycoforms possessing the same polypeptide backbone but differing in the site of glycosylation and/or in the structures of pendant glycans, from which single glycoforms are difficult to isolate. The urgent need for glycan-defined glycoproteins in both detailed structure-function relationship studies and therapeutic applications has stimulated an extensive interest in developing various methods for manipulating protein glycosylation. This review highlights emerging technologies that hold great promise in making a variety of glycan-defined glycoproteins, with a particular emphasis in the following three areas: specific glycoengineering of host biosynthetic pathways, in vitro chemoenzymatic glycosylation remodeling, and chemoselective and site-specific glycosylation of proteins.
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Affiliation(s)
- Lai-Xi Wang
- Institute of Human Virology and Department of Biochemistry & Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
| | - Joseph V. Lomino
- Institute of Human Virology and Department of Biochemistry & Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
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16
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Zou G, Ochiai H, Huang W, Yang Q, Li C, Wang LX. Chemoenzymatic synthesis and Fcγ receptor binding of homogeneous glycoforms of antibody Fc domain. Presence of a bisecting sugar moiety enhances the affinity of Fc to FcγIIIa receptor. J Am Chem Soc 2011; 133:18975-91. [PMID: 22004528 DOI: 10.1021/ja208390n] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Structurally well-defined IgG-Fc glycoforms are highly demanded for understanding the effects of glycosylation on an antibody's effector functions. We report in this paper chemoenzymatic synthesis and Fcγ receptor binding of an array of homogeneous IgG-Fc glycoforms. The chemoenzymatic approach consists of the chemical synthesis of defined N-glycan oxazolines as donor substrates, the expression of the Fc domain in a CHO cell line in the presence of an α-mannosidase inhibitor kifunensine, and an endoglycosidase-catalyzed glycosylation of the deglycosylated Fc domain (GlcNAc-Fc homodimer) with the synthetic glycan oxazolines. The enzyme from Arthrobacter protophormiae (Endo-A) was found to be remarkably efficient to take various modified N-glycan core oxazolines, including the bisecting sugar-containing derivatives, for Fc glycosylation remodeling, resulting in the formation of the corresponding homogeneous Fc glycoforms. Nevertheless, neither Endo-A nor the Mucor hiemalis endoglycosidase mutants (EndoM-N175A and EndoM-N175Q) were able to transfer full-length complex-type N-glycan to the Fc domain, implicating the limitations of these two enzymes in Fc glycosylation remodeling. Surface plasmon resonance (SPR) binding studies with the synthetic IgG-Fc glycoforms unambiguously proved that the presence of a bisecting GlcNAc moiety could significantly enhance the binding of Fc to FcγRIIIa, the activating Fcγ receptor, independent of Fc core-fucosylation. Interestingly, the Fc glycoforms carrying an unusual bisecting sugar moiety such as a mannose or a LacNAc moiety also demonstrated enhanced affinity to FcγRIIIa. On the orther hand, the presence of a bisecting GlcNAc or core-fucosylation had little effect on the affinity of Fc to the inhibitory Fcγ receptor, FcγRIIb. Our experimental data also showed that the α-linked mannose residues in the pentasaccharide Man3GlcNAc2 core was essential to maintain a high affinity of Fc to both FcγRIIIa and FcγRIIb. The synthetic homogeneous Fc glycoforms thus provide a useful tool for elucidating how a fine Fc N-glycan structure precisely affects the function of the Fc domain.
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Affiliation(s)
- Guozhang Zou
- Institute of Human Virology and Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
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17
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MacPherson IS, Temme JS, Habeshian S, Felczak K, Pankiewicz K, Hedstrom L, Krauss IJ. Multivalent Glycocluster Design through Directed Evolution. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201105555] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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