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Zhang H, Li Q, Zhou H, Feng M, Zhao Y, Zhou R, Chen L, Tachibana H, Cheng X. Identification and characterization of a carbohydrate recognition domain-like region in Entamoeba histolytica Gal/GalNAc lectin intermediate subunit. Microbiol Spectr 2024:e0053824. [PMID: 39365081 DOI: 10.1128/spectrum.00538-24] [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: 02/29/2024] [Accepted: 09/06/2024] [Indexed: 10/05/2024] Open
Abstract
Entamoeba histolytica is an enteric protozoan parasite that causes human amebic colitis and extraintestinal abscesses. As a prerequisite for parasite colonization and invasion, adherence of E. histolytica is predominantly mediated by galactose (Gal)- and N-acetyl-d-galactosamine (GalNAc)-inhibitable lectins. The intermediate subunit (Igl) of Gal-/GalNAc-inhibitable lectin is a cysteine-rich protein containing multiple CXXC motifs and is considered a key factor affecting trophozoite's pathogenicity. However, details of the function of Igl during parasite adherence remain unclear. Here, using segmentally expressed Igl proteins and a CHO cell model transfected with Igl fragments, we identified a carbohydrate-recognition domain (CRD)-like region between amino acids 989 and 1,088. Through single- and double-point mutations in the Igl segments, two core CXXC motifs responsible for carbohydrate recognition in the CRD-like region, which are highly conserved among several lectins, were confirmed. In addition to adhesion, the roles of CRD-like region and its core CXXC motifs in various pathogenic effects were further explored. To our knowledge, this is the first report showing an adhesion-related region in E. histolytica Igl. The identification and characterization of this CRD-like region provides further insights into molecular mechanisms underlying E. histolytica pathogenicity and also aids in the determination of a potential drug target in this parasite. IMPORTANCE Entamoeba histolytica adhesion mainly depends on galactose (Gal)-/N-acetyl-d-galactosamine (GalNAc)-inhibitable lectins, subsequently triggering a series of amebic reactions. Among the three subunits of Gal-/GalNAc-inhibitable lectin, heavy subunit and intermediate subunit (Igl) have exhibited lectin activity, but that of Igl remains poorly understood. In this study, we confirmed a carbohydrate-recognition domain (CRD)-like limiting region in E. histolytica Igl and further identified its two core CXXC motifs responsible for carbohydrate recognition. Moreover, the role of Igl's CRD-like region and its CXXC motifs in hemolysis and pathogenic effects was explored. This is the first study to determine an adhesion-related region in E. histolytica Igl protein, providing a new reference direction for subsequent research studies. Since the potential homogeneity of galectin-2 in several mammals and Igl CRD-like region, it could be meaningful to relate the corresponding pathogeneses and phenotypes of these two proteins. Except for adhesion, studies on the involvement of Igl CRD-like region in different parasite-host interactions are also promising.
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Affiliation(s)
- Hongze Zhang
- Department of Medical Microbiology and Parasitology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Qingshan Li
- Department of Medical Microbiology and Parasitology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Hang Zhou
- Department of Medical Microbiology and Parasitology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Meng Feng
- Department of Medical Microbiology and Parasitology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Yanqing Zhao
- Department of Medical Microbiology and Parasitology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Ruixue Zhou
- Department of Medical Microbiology and Parasitology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Lijun Chen
- Department of Medical Microbiology and Parasitology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Hiroshi Tachibana
- Department of Infectious Diseases, Tokai University School of Medicine, Isehara, Kanagawa, Japan
| | - Xunjia Cheng
- Department of Medical Microbiology and Parasitology, School of Basic Medical Sciences, Fudan University, Shanghai, China
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Novel hemagglutinating, hemolytic and cytotoxic activities of the intermediate subunit of Entamoeba histolytica lectin. Sci Rep 2015; 5:13901. [PMID: 26354528 PMCID: PMC4564812 DOI: 10.1038/srep13901] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Accepted: 08/10/2015] [Indexed: 01/13/2023] Open
Abstract
Galactose and N-acetyl-D-galactosamine (Gal/GalNAc) inhibitable lectin of Entamoeba histolytica, a common protozoan parasite, has roles in pathogenicity and induction of protective immunity in mouse models of amoebiasis. The lectin consists of heavy (Hgl), light (Lgl), and intermediate (Igl) subunits. Hgl has lectin activity and Lgl does not, but little is known about the activity of Igl. In this study, we assessed various regions of Igl for hemagglutinating activity using recombinant proteins expressed in Escherichia coli. We identified a weak hemagglutinating activity of the protein. Furthermore, we found novel hemolytic and cytotoxic activities of the lectin, which resided in the carboxy-terminal region of the protein. Antibodies against Igl inhibited the hemolytic activity of Entamoeba histolytica trophozoites. This is the first report showing hemagglutinating, hemolytic and cytotoxic activities of an amoebic molecule, Igl.
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Jayaraman N. Multivalent ligand presentation as a central concept to study intricate carbohydrate–protein interactions. Chem Soc Rev 2009; 38:3463-83. [DOI: 10.1039/b815961k] [Citation(s) in RCA: 185] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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Yura H, Ishihara M, Kanatani Y, Takase B, Hattori H, Suzuki S, Kawakami M, Matsui T. Interaction Study between Synthetic Glycoconjugate Ligands and Endocytic Receptors Using Flow Cytometry. ACTA ACUST UNITED AC 2006; 139:637-43. [PMID: 16672263 DOI: 10.1093/jb/mvj077] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Flow cytometric analysis of synthetic galactosyl polymers, asialofetuin and LDL derivatives labeled with FITC (Fluorescein Isothiocyanate) was carried out to determine the phenotypes of endocytic receptors, such as asialoglycoprotein (ASPG) and the LDL receptor, on various types of cells. When FITC-labeled galactosyl polystyrene (GalCPS), being a synthetic ligand of ASPG, was applied to rat hepatocytes and human cancer cells (Hep G2 and Chang Liver), surface fluorescence intensities varied according to receptor expression on the cells. The fluorescence intensity originates from the calcium-dependent binding of the FITC-labeled GalCPS. Although unaltered by pre-treatment with glucosyl polystyrene (GluCPS), fetuin and LDL, the fluorescence intensity was suppressed by pre-treatment with (non-labeled) GalCPS and asialofetuin. Flow cytometry allowed us to demonstrate that the calcium-dependent binding of FITC-labeled LDL (prepared from rabbits) upon the addition of 17alpha-ethinyl estradiol enhances LDL receptor expression, and the expression is suppressed upon the addition of a monoclonal antibody to the LDL receptor. The binding efficiency based on the combination of FITC-labeled ligands suggests a possible application for the classification of cell types and conditions corresponding to endocytic receptor expression without the need for immuno-active antibodies or radiolabeled substances. Furthermore, the synthetic glycoconjugate (GalCPS) is shown to be a sensitive and useful marker for classification based on cell phenotype using flow cytometry.
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Affiliation(s)
- Hirofumi Yura
- NeTech Inc. KSP West 300-H, Sakado 3-2-1, Takatsu, Kawasaki, Kanagawa 213-0012
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Bandaru NM, Sampath S, Jayaraman N. Synthesis and Langmuir studies of bivalent and monovalent alpha-D-mannopyranosides with lectin Con A. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:9591-6. [PMID: 16207040 DOI: 10.1021/la051433o] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Highly avid interaction between carbohydrate ligands and lectin receptors nominally requires the ligand presentation in a clustered form. We present herein an approach involving Langmuir monolayer formation of the sugar ligands and the assessment of their lectin binding at the air-water interface. Bivalent alpha-D-mannopyranoside containing the glycolipid ligand was used to study its binding profiles with lectin Con A, in comparison to the corresponding monovalent glycolipid. In addition to the bivalent and monovalent nature of the glycolipid ligands at the molecular level, the ligand densities at the monolayer level were varied with the aid of a nonsugar lipid molecule so as to obtain mixed monolayers with various sugar-nonsugar ratios. Lectin binding of bivalent and monovalent ligands at different ratios was monitored by differential changes in the surface area per molecule of the mixed monolayer, with and without the lectin. The present study shows that maximal binding of the lectin to the bivalent ligand occurs at lower sugar densities at the interface ( approximately 10% sugar in the mixed monolayer) than for that of the monovalent ligand ( approximately 20% sugar in the mixed monolayer). It is observed that complete coverage of the monolayer with only the sugar ligands does not allow all of the sugars to be functionally active.
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Affiliation(s)
- Narasimha Murthy Bandaru
- Department of Organic Chemistry and Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560 012, India
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6
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Frederick JR, Petri WA. Roles for the galactose-/N-acetylgalactosamine-binding lectin of Entamoeba in parasite virulence and differentiation. Glycobiology 2005; 15:53R-59R. [PMID: 16037494 DOI: 10.1093/glycob/cwj007] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Entamoeba histolytica, an intestinal protozoan parasite, is a major cause of morbidity and mortality in developing countries. The pathology of the disease is caused by the colonization of the large intestine by the amoebic trophozoites and the invasion of the intestinal epithelium. Some of the trophozoites will eventually differentiate into the infectious cyst form, allowing them to be transmitted out of the bowel and into water supplies to be passed from person to person. Both the virulence of the organism and the differentiation process relies on a galactose-/N-acetylgalactosamine (GalNAc)-binding lectin that is expressed on the surface of trophozoites. The functional activity of this lectin has been shown to be involved in host cell binding, cytotoxicity, complement resistance, induction of encystation, and generation of the cyst wall. The role of the lectin in both differentiation and virulence suggests that it may be a pivotal molecule that determines the severity of the infection from a commensal state resulting from increased encystation to an invasive state. The lectin-glycan interactions that initiate these diverse processes are discussed with emphasis on comparing the binding of host ligands and the interactions involved in encystation.
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Affiliation(s)
- Jesse R Frederick
- Division of Infectious Diseases, University of Virginia Health System, MR4 Building, Room 2115, Charlottesville, VA 22908-1340, USA
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Srinivas O, Mitra N, Surolia A, Jayaraman N. Photoswitchable cluster glycosides as tools to probe carbohydrate-protein interactions: synthesis and lectin-binding studies of azobenzene containing multivalent sugar ligands. Glycobiology 2005; 15:861-73. [PMID: 15872151 DOI: 10.1093/glycob/cwi069] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Synthetic cluster glycosides have often been used to unravel mechanisms of carbohydrate-protein interactions. Although synthetic cluster glycosides are constituted on scaffolds to achieve high avidities in lectin binding, there have been no known attempts to modulate the orientations of the sugar clusters with the aid of a functional scaffold onto which the sugar units are linked. Herein, we describe synthesis, physical, and lectin-binding studies of a series of alpha-D-mannopyranoside and beta-D-galactopyranosyl-(1-->4)-beta-D-glucopyranoside glycoclusters that are attached to a photoswitchable azobenzenoid core. These glycoclusters were synthesized by the amidation of amine-tethered glycopyranosides with azobenzene carbonyl chlorides. From kinetic studies, the cis forms of the azobenzene-glycopyranoside derivative were found to be more stable in aqueous solutions than in organic solvents. Molecular modeling studies were performed to estimate the relative geometries of the photoswitchable glycoclusters in the trans- and cis-isomeric forms. Isothermal titration calorimetry (ITC) was employed to assess the binding of these glycoclusters to lectins peanut agglutinin (PNA) and concanavalin A (Con A). Although binding affinities were enhanced several orders higher as the valency of the sugar was increased, a biphasic-binding profile in ITC plots was observed during few glycoclusters lectin-binding processes. The biphasic-binding profile indicates a "cooperativity" in the binding process. An important outcome of this study is that in addition to inherent clustering of the sugar units as a molecular feature, an induced clustering emanates because of the isomerization of the trans form of the azobenzene scaffold to the cis-isomeric form.
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Affiliation(s)
- Oruganti Srinivas
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, Karnataka, India
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Affiliation(s)
- Rashidul Haque
- International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh
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Petri WA, Haque R, Mann BJ. The bittersweet interface of parasite and host: lectin-carbohydrate interactions during human invasion by the parasite Entamoeba histolytica. Annu Rev Microbiol 2003; 56:39-64. [PMID: 12142490 DOI: 10.1146/annurev.micro.56.012302.160959] [Citation(s) in RCA: 245] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Entamoeba histolytica, as its name suggests, is an enteric parasite with a remarkable ability to lyse host tissues. However, the interaction of the parasite with the host is more complex than solely destruction and invasion. It is at the host-parasite interface that cell-signaling events commit the parasite to (a) commensal, noninvasive infection, (b) developmental change from trophozoite to cyst, or (c) invasion and potential death of the human host. The molecule central to these processes is an amebic cell surface protein that recognizes the sugars galactose (Gal) and N-acetylgalactosamine (GalNAc) on the surface of host cells. Engagement of the Gal/GalNAc lectin to the host results in cytoskeletal reorganization in the parasite. The parasite cytoskeleton regulates the extracellular adhesive activity of the lectin and recruits to the host-parasite interface factors required for parasite survival within its host. If the parasite lectin attaches to the host mucin glycoproteins lining the intestine, the result is commensal infection. In contrast, attachment of the lectin to a host cell surface glycoprotein leads to lectin-induced host cell calcium transients, caspase activation, and destruction via apoptosis. Finally, trophozoite quorum sensing via the lectin initiates the developmental pathway resulting in encystment. The structure and function of the lectin that controls these divergent cell biologic processes are the subject of this review.
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Affiliation(s)
- William A Petri
- Division of Infectious Diseases, University of Virginia, MR4 Bldg Room 2115, Lane Road, Charlottesville 22908-1340, USA.
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11
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Takeuchi H, Kato K, Hassan H, Clausen H, Irimura T. O-GalNAc incorporation into a cluster acceptor site of three consecutive threonines. Distinct specificity of GalNAc-transferase isoforms. EUROPEAN JOURNAL OF BIOCHEMISTRY 2002; 269:6173-83. [PMID: 12473113 DOI: 10.1046/j.1432-1033.2002.03334.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
O-Glycosylation of three consecutive Thr residues in a fluorescein-conjugated peptide PTTTPLK - which mimics a portion of mucin 2 - by four isozymes of UDP-N-acetylgalactosaminyltransferases (pp-GalNAc-T1, T2, T3, or T4) was investigated. Partially glycosylated versions of this peptide, PT*TTPLK, PTTT*PLK, PT*TT*PLK, PTT*T*PLK, PT* degrees TTPLK, and PTTT* degrees PLK (*, N-acetylgalactosamine; degrees, galactose), were also tested. The products were separated by RP-HPLC and characterized by MALDI-TOF MS and peptide sequencing. The first and the third Thr residues act as the peptide's initial glycosylation sites for pp-GalNAc-T4, which were different from the sites for pp-GalNAc-T1 and T2 (the first Thr residue) or T3 (the third Thr residue) shown in our previous report. All pp-GalNAc-T isozymes tested exhibited distinct specificities toward glycopeptides. The most notable findings were: (a) prior incorporation of an N-acetylgalactosamine residue at the third Thr greatly enhanced N-acetylgalactosamine incorporation into the other Thr residues when pp-GalNAc-T2, T3, or T4 were used; (b) the enhancing effect of the N-acetylgalactosamine residue on the third Thr was completely abrogated by galactosylation of this N-acetylgalactosamine; (c) prior incorporation of an N-acetylgalactosamine at the first Thr did not have any enhancing effect; (d) pp-GalNAc-T2 was unique as it transferred N-acetylgalactosamine into the second Thr residue only when N-acetylgalactosamine was attached to the third one.
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Affiliation(s)
- Hideyuki Takeuchi
- Laboratory of Cancer Biology and Molecular Immunology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Japan
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12
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Abstract
Multivalent neoglycoconjugates with well-defined structures have considerable potential as inhibitors of cell surface protein-carbohydrate interactions and as tools for studying such recognition processes in vitro. In this review, we outline strategies and synthetic methods for making one such class of neoglycoconjugates based on dendrimers--the so-called glycodendrimers. Glycodendrimers can be classified as: (i) carbohydrate-coated; (ii) carbohydrate-centered; and (iii) fully carbohydrate-based. Approaches to their construction have included both the modification of commercially available dendrimers and de novo dendrimer synthesis. Examples from the authors' and other laboratories are drawn upon to illustrate design considerations and the application of dendritic synthetic principles--including divergent and convergent syntheses--for making glycodendrimers. Key coupling reactions for the synthesis of glycodendrimers include: amide and thiourea formation; glycosylation; photoaddition to allyl ethers; and reductive amination. The advantages and disadvantages of using protected and unprotected saccharide building blocks and potential applications for glycodendrimers in both biotechnology and materials science are also discussed.
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Affiliation(s)
- W Bruce Turnbull
- Department of Chemistry and Biochemistry, University of California Los Angeles, 90095-1569, USA.
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Srinivas O, Mitra N, Surolia A, Jayaraman N. Photoswitchable multivalent sugar ligands: synthesis, isomerization, and lectin binding studies of azobenzene-glycopyranoside derivatives. J Am Chem Soc 2002; 124:2124-5. [PMID: 11878960 DOI: 10.1021/ja0173066] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Coating of azobenzene chromophore with multivalent sugar ligands has been accomplished. Such sugar coating allows the study of the isomerization properties of this chromophore in aqueous solutions. The predominantly cis-isomer-containing photostationary state (PS) mixture of these azobenzene derivatives is found to be stable for hours. The rate constants for their isomerization, as well as the Arrhenius activation energies, are determined experimentally. An assessment of the lectin binding properties of the lactoside bearing isomeric azobenzene derivatives, by isothermal calorimetric methods, reveals the existence of an unusual cooperativity in their binding to lectin peanut agglutinin. Thermodynamic parameters evaluated for the trans and the PS mixture are discussed, in detail, for the lactoside bearing bivalent azobenzene derivative.
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Affiliation(s)
- Oruganti Srinivas
- Department of Organic Chemistry and Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India
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Houseman BT, Mrksich M. Model Systems for Studying Polyvalent Carbohydrate Binding Interactions. ACTA ACUST UNITED AC 2001. [DOI: 10.1007/3-540-45010-6_1] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/03/2023]
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Yamazaki N, Kojima S, Bovin NV, André S, Gabius S, Gabius HJ. Endogenous lectins as targets for drug delivery. Adv Drug Deliv Rev 2000; 43:225-44. [PMID: 10967228 DOI: 10.1016/s0169-409x(00)00071-5] [Citation(s) in RCA: 163] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
To minimize side effects of drugs it would be ideal to target them exclusively to those cell types which require treatment. As a means to this end prototypical cellular recognition systems pique our interest to devise biomimetic strategies. Since oligosaccharides of glycoconjugates outmatch other information-carrying biomolecules (proteins, nucleic acids) in theoretical storage capacity by far, work on the sugar code can spark off development of effective targeting devices. Conjugation of custom-made glycan epitopes to proteins or biocompatible non-immunogenic polymeric scaffolds produces neoglycoconjugates with purpose-adaptable properties. In the interplay with endogenous receptors such as lectins, suitable oligosaccharides such as histo-blood group trisaccharides as parts of neoglycoconjugates have already proven their practical applications in histopathology. Elucidation of the structure of cell lectins with currently five main families aids to tailor ligand characteristics rationally. They include the types of functional groups and their topological presentation to optimize the bimolecular binding as well as the optimal spatial clustering and spacer characteristics to exploit cooperativity. Indeed, the potent trivalent cluster glycosides designed for the C-type asialoglycoprotein receptors furnish an instructive example how to turn the theoretical guideline on ligand modification into nM-affinity. By placing emphasis on tissue lectins as targets of neoglycoconjugate-mediated drug delivery, the long-term perspective is opened to likewise test members of these families themselves for routing of therapeutic payloads, aiming at cell addressins. This review illustrates the conceivable potential which work on the sugar code with custom-made neoglycoconjugates and tissue lectins can have in store for drug delivery.
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Affiliation(s)
- N Yamazaki
- Materials Design Laboratory, Department of Organic Materials, National Institute of Materials and Chemical Research, 1-1 Higashi, Tsukuba-City, 305, Ibaraki, Japan.
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Ramakrishnan G, Lee S, Mann BJ, Petri WA. Entamoeba histolytica: deletion of the GPI anchor signal sequence on the Gal/GalNAc lectin light subunit prevents its assembly into the lectin heterodimer. Exp Parasitol 2000; 96:57-60. [PMID: 11038322 DOI: 10.1006/expr.2000.4543] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Adherence and cytotoxicity of Entamoeba histolytica require the function of a heterodimeric galactose and N-acetylgalactosamine (Gal/GalNAc)-specific lectin. The lectin heavy subunit (Hgl) contains a carbohydrate recognition domain and mediates inside-out cell signaling via its cytoplasmic tail. The function of the lectin light subunit (Lgl) is unknown. The lectin has a unique mechanism of membrane association: Hgl is transmembrane but Lgl is glycosylphosphatidylinositol (GPI) anchored. The role of the GPI anchor signal sequence in heterodimer assembly was tested. Epitope-tagged Lgl with or without the GPI anchor addition signal was expressed in E. histolytica trophozoites. Tagged Lgl did not assemble with Hgl into a lectin heterodimer in the absence of the GPI addition signal. Consistent with previous results that only the Hgl subunit mediates adherence, the monomeric Lgl without the GPI anchor signal lacked Gal/GalNAc-binding activity.
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Affiliation(s)
- G Ramakrishnan
- Departments of Medicine, Microbiology and Pathology, University of Virginia Health System, Charlottesville, Virginia 22908-1340, USA
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André S, Frisch B, Kaltner H, Desouza DL, Schuber F, Gabius HJ. Lectin-mediated drug targeting: selection of valency, sugar type (Gal/Lac), and spacer length for cluster glycosides as parameters to distinguish ligand binding to C-type asialoglycoprotein receptors and galectins. Pharm Res 2000; 17:985-90. [PMID: 11028946 DOI: 10.1023/a:1007535506705] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
PURPOSE Common oligosaccharides of cellular glycoconjugates are ligands for more than one type of endogenous lectin. Overlapping specificities to beta-galactosides of C-type lectins and galectins can reduce target selectivity of carbohydrate-ligand-dependent drug targeting. The purpose of this study is to explore distinct features of ligand presentation and structure for design of cluster glycosides to distinguish between asialoglycoprotein-specific (C-type) lectins and galectins. METHODS Extent of binding of labeled sugar receptors to two types of matrix-immobilized (neo)glycoproteins and to cells was evaluated in the absence and presence of competitive inhibitors. This panel comprised synthetic mono-, bi-, and trivalent glycosides with two spacer lengths and galactose or lactose as ligand part. RESULTS In contrast to C-type lectins of hepatocytes and macrophages, bi- and trivalent glycosides do not yield a notable glycoside cluster effect for galectins-1 and -3. Also, these Ca2+-independent galactoside-binding proteins prefer to home in on lactose-bearing glycosides relative to galactose as ligand, while spacer length requirements were rather similar. CONCLUSIONS Trivalent cluster glycosides with Gal/GalNAc as ligand markedly distinguish between C-type lectins and galectins. Undesired side reactivities to galectins for C-type lectin drug delivery will thus be minimal.
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Affiliation(s)
- S André
- Institut für Physiologische Chemie, Tierärztliche Fakultät, Ludwig-Maximilians-Universität, Germany
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Tavares P, Sansonetti P, Guillén N. Cell polarization and adhesion in a motile pathogenic protozoan: role and fate of the Entamoeba histolytica Gal/GalNAc lectin. Microbes Infect 2000; 2:643-9. [PMID: 10884615 DOI: 10.1016/s1286-4579(00)00361-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The human pathogenic protozoan Entamoeba histolytica is a motile cell polarized into a front pseudopod and a rear uroid. The amoebic Gal/GalNAc surface lectin is a major adhesion molecule composed of an immunodominant 170-kDa heavy subunit, mostly extracellular except for a short cytoplasmic tail, and of an extracellular light subunit. The binding of multivalent ligands triggers lectin capping and recruitment to the uroid. The properties of the Gal/GalNAc lectin and its role in amoeba adhesion and uroid polarization are reviewed in the context of the molecular mechanisms underlying cell polarization and locomotion.
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Affiliation(s)
- P Tavares
- Unité de pathogénie microbienne moléculaire et Inserm U389, Institut Pasteur, Rue du Dr. Roux 28, F-75724 cedex 15, Paris, France
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Lauc G, Lee RT, Dumiae J, Lee YC. Photoaffinity glycoprobes-a new tool for the identification of lectins. Glycobiology 2000; 10:357-64. [PMID: 10764823 DOI: 10.1093/glycob/10.4.357] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
One of the proposed functions for the carbohydrate structures on glycoconjugates is the transfer of information through interaction with specific lectin receptors. However, the number of elucidated functional lectin-carbohydrate interactions is still relatively small, largely due to the lack of adequate methods to identify lectin activity in complex biological samples. Aiming to solve this problem, we have developed a method based on the novel group of compounds we named glycoprobes. The glycoprobe consists of three vital parts: (1) glycan, (2) digoxin tag, and (3) photoreactive crosslinker. When incubated in dark, oligosaccharide part of the glycoprobe forms a complex with lectin. After illumination, covalent link between the probe and the lectin is formed resulting in a digoxin-tagged lectin. Using antibodies against digoxin, this complex can easily be identified immuno/cytochemically, or by Western blots. To demonstrate the applicability of glycoprobes we have used Man(9)-glycoprobe (containing Man(9)oligosaccharide) and YEE(ahGalNAc)(3)-glycoprobe (containing a synthetic neoglycopeptide with three terminal N-acetyl-galactosamine residues; Lee and Lee, Glycoconjugate J., 1987,4, 317) to identify lectins in bovine serum and rat liver membranes. The simplicity of the method enables its application in routine monitoring of changes in lectin activity during various developmental or pathological processes. An example of GalNAc-binding analysis in human serum is shown.
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Affiliation(s)
- G Lauc
- Department of Biochemistry and Molecular Biology, Faculty of Pharmacy and Biochemistry, University of Zagreb, Ante Kovaèiaea 1, 10000 Zagreb, Croatia
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André S, Ortega PJ, Perez MA, Roy R, Gabius HJ. Lactose-containing starburst dendrimers: influence of dendrimer generation and binding-site orientation of receptors (plant/animal lectins and immunoglobulins) on binding properties. Glycobiology 1999; 9:1253-61. [PMID: 10536041 DOI: 10.1093/glycob/9.11.1253] [Citation(s) in RCA: 145] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Starburst glycodendrimers offer the potential to serve as high-affinity ligands for clinically relevant sugar receptors. In order to define areas of application, their binding behavior towards sugar receptors with differential binding-site orientation but identical monosaccharide specificity must be evaluated. Using poly(amidoamine) starburst dendrimers of five generations, which contain the p-isothiocyanato derivative of p-aminophenyl-beta-D-lactoside as ligand group, four different types of galactoside-binding proteins were chosen for this purpose, i.e., the (AB)(2)-toxic agglutinin from mistletoe, a human immunoglobulin G fraction, the homodimeric galectin-1 with its two binding sites at opposite ends of the jelly-roll-motif-harboring protein and monomeric galectin-3. Direct solid-phase assays with surface-immobilized glycodendrimers resulted in obvious affinity enhancements by progressive core branching for the plant agglutinin and less pronounced for the antibody and galectin-1. High density of binding of galectin-3 with modest affinity increases only from the level of the 32-mer onwards points to favorable protein-protein interactions of the monomeric lectin and a spherical display of the end groups without a major share of backfolding. When the inhibitory potency of these probes was evaluated as competitor of receptor binding to an immobilized neoglycoprotein or to asialofetuin, a marked selectivity was detected. The 32- and 64-mers were second to none as inhibitors for the plant agglutinin against both ligand-exposing matrices and for galectin-1 on the matrix with a heterogeneous array of interglycoside distances even on the per-sugar basis. In contrast, a neoglycoprotein with the same end group was superior in the case of the antibody and, less pronounced, monomeric galectin-3. Intimate details of topological binding-site presentation and the ligand display on different generations of core assembly are major operative factors which determine the potential of dendrimers for applications as lectin-targeting device, as attested by these observations.
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Affiliation(s)
- S André
- Institute of Physiological Chemistry, Faculty of Veterinary Medicine, Ludwig-Maximilians-University, Veterinärstrasse 13, D-80539 Munich, Germany
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Coppi A, Eichinger D. Regulation of Entamoeba invadens encystation and gene expression with galactose and N-acetylglucosamine. Mol Biochem Parasitol 1999; 102:67-77. [PMID: 10477177 DOI: 10.1016/s0166-6851(99)00085-7] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Encystation of Entamoeba invadens parasites is prevented by the presence of free galactose or N-acetylglucosamine in the encystation medium. Galactose prevents the formation of amoeba cellular aggregates which develop during the early phase of encystation, suggesting the presence of functional cell surface galactose-binding molecules, whereas N-acetylglucosamine allows aggregation to occur and prevents cyst formation at a later point. While studying sugar inhibition of amoeba encystation, it was found that high efficiency encystation required the inclusion in encystation medium of precise amounts of polyvalent galactose-terminated molecules, and these molecules could be supplied by serum or by defined glycoconjugates, including mucin. Addition of free galactose to encystation medium prevented the accumulation of three transcripts which are normally upregulated during encystation, and N-acetylglucosamine prevented accumulation of one of the transcripts. These results suggest the presence of distinct sugar-sensitive pathways that regulate differentiation of the amoeba trophozoite into infectious cysts.
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Affiliation(s)
- A Coppi
- Department of Medical and Molecular Parasitology, New York University, School of Medicine, NY 10010, USA
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