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Osterne VJS, De Sloover G, Van Damme EJM. Revisiting legume lectins: Structural organization and carbohydrate-binding properties. Carbohydr Res 2024; 544:109241. [PMID: 39153325 DOI: 10.1016/j.carres.2024.109241] [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: 05/28/2024] [Revised: 07/18/2024] [Accepted: 08/13/2024] [Indexed: 08/19/2024]
Abstract
Legume lectins are a diverse family of carbohydrate-binding proteins that share significant similarities in their primary, secondary, and tertiary structures, yet exhibit remarkable variability in their quaternary structures and carbohydrate-binding specificities. The tertiary structure of legume lectins, characterized by a conserved β-sandwich fold, provides the scaffold for the formation of a carbohydrate-recognition domain (CRD) responsible for ligand binding. The structural basis for the binding is similar between members of the family, with key residues interacting with the sugar through hydrogen bonds, hydrophobic interactions, and van der Waals forces. Variability in substructures and residues within the CRD are responsible for the large array of specificities and enable legume lectins to recognize diverse sugar structures, while maintaining a consistent structural fold. Therefore, legume lectins can be classified into several specificity groups based on their preferred ligands, including mannose/glucose-specific, N-acetyl-d-galactosamine/galactose-specific, N-acetyl-d-glucosamine-specific, l-fucose-specific, and α-2,3 sialic acid-specific lectins. In this context, this review examined the structural aspects and carbohydrate-binding properties of representative legume lectins and their specific ligands in detail. Understanding the structure/binding relationships of lectins continues to provide valuable insights into their biological roles, while also assisting in the potential applications of these proteins in glycobiology, diagnostics, and therapeutics.
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Affiliation(s)
- Vinicius J S Osterne
- Laboratory of Biochemistry and Glycobiology, Department of Biotechnology, Ghent University, Proeftuinstraat 86, 9000, Ghent, Belgium
| | - Gilles De Sloover
- Laboratory of Biochemistry and Glycobiology, Department of Biotechnology, Ghent University, Proeftuinstraat 86, 9000, Ghent, Belgium
| | - Els J M Van Damme
- Laboratory of Biochemistry and Glycobiology, Department of Biotechnology, Ghent University, Proeftuinstraat 86, 9000, Ghent, Belgium.
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2
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Zhang J, Li Z, Pang Y, Fan Y, Ai HW. Genetically Encoded Boronolectin as a Specific Red Fluorescent UDP-GlcNAc Biosensor. ACS Sens 2023; 8:2996-3003. [PMID: 37480329 PMCID: PMC10663054 DOI: 10.1021/acssensors.3c00409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/24/2023]
Abstract
There is great interest in developing boronolectins that are synthetic lectin mimics containing a boronic acid functional group for reversible recognition of diol-containing molecules, such as glycans and ribonucleotides. However, it remains a significant challenge to gain specificity. Here, we present a genetically encoded boronolectin which is a hybrid protein consisting of a noncanonical amino acid (ncAA) p-boronophenylalanine (pBoF), natural-lectin-derived peptide sequences, and a circularly permuted red fluorescent protein (cpRFP). The genetic encodability permitted a straightforward protein engineering process to derive a red fluorescent biosensor that can specifically bind uridine diphosphate N-acetylglucosamine (UDP-GlcNAc), an important nucleotide sugar involved in metabolic sensing and cell signaling. We further characterized the resultant boronic acid- and peptide-assisted UDP-GlcNAc sensor (bapaUGAc) both in vitro and in live mammalian cells. Because UDP-GlcNAc in the endoplasmic reticulum (ER) and Golgi apparatus plays essential roles in glycosylating biomolecules in the secretory pathway, we genetically expressed bapaUGAc in the ER and Golgi and validated the sensor for its responses to metabolic disruption and pharmacological inhibition. In addition, we combined bapaUGAc with UGAcS, a recently reported green fluorescent UDP-GlcNAc sensor based on an alternative sensing mechanism, to monitor UDP-GlcNAc level changes in the ER and cytosol simultaneously. We expect our work to facilitate the future development of specific boronolectins for carbohydrates. In addition, this newly developed genetically encoded bapaUGAc sensor will be a valuable tool for studying UDP-GlcNAc and glycobiology.
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Affiliation(s)
- Jing Zhang
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, 1340 Jefferson Park Ave, Charlottesville, Virginia, 22908, USA
- Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, Virginia, 22908, USA
| | - Zefan Li
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, 1340 Jefferson Park Ave, Charlottesville, Virginia, 22908, USA
- Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, Virginia, 22908, USA
| | - Yu Pang
- Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, Virginia, 22908, USA
- Department of Chemistry, University of Virginia, Charlottesville, Virginia, 22904, USA
| | - Yichong Fan
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, 1340 Jefferson Park Ave, Charlottesville, Virginia, 22908, USA
- Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, Virginia, 22908, USA
| | - Hui-wang Ai
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, 1340 Jefferson Park Ave, Charlottesville, Virginia, 22908, USA
- Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, Virginia, 22908, USA
- Department of Chemistry, University of Virginia, Charlottesville, Virginia, 22904, USA
- UVA Comprehensive Cancer Center, University of Virginia, Charlottesville, Virginia, 22903, USA
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Zhang J, Li Z, Pang Y, Fan Y, Ai HW. Genetically Encoded Boronolectin as a Specific Red Fluorescent UDP-GlcNAc Biosensor. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.01.530644. [PMID: 36909602 PMCID: PMC10002721 DOI: 10.1101/2023.03.01.530644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
Abstract
There is great interest in developing boronolectins, which are synthetic lectin mimics containing a boronic acid functional group for reversible recognition of diol-containing molecules, such as glycans and ribonucleotides. However, it remains a significant challenge to gain specificity. Here, we present a genetically encoded boronolectin, which is a hybrid protein consisting of a noncanonical amino acid (ncAA) p-boronophenylalanine (pBoF), natural-lectin-derived peptide sequences, and a circularly permuted red fluorescent protein (cpRFP). The genetic encodability permitted a straightforward protein engineering process to derive a red fluorescent biosensor that can specifically bind uridine diphosphate N-acetylglucosamine (UDP-GlcNAc), an important nucleotide sugar involved in metabolic sensing and cell signaling. We further characterized the resultant boronic acid-and peptide-assisted UDP-GlcNAc sensor (bapaUGAc) both in vitro and in live mammalian cells. Because UDP-GlcNAc in the endoplasmic reticulum (ER) and Golgi apparatus plays essential roles in glycosylating biomolecules in the secretory pathway, we genetically expressed bapaUGAc in the ER and Golgi and validated the sensor for its responses to metabolic disruption and pharmacological inhibition. In addition, we combined bapaUGAc with UGAcS, a recently reported green fluorescent UDP-GlcNAc sensor based on an alternative sensing mechanism, to monitor UDP-GlcNAc level changes in the ER and cytosol simultaneously. We expect our work to facilitate the future development of specific boronolectins for carbohydrates. In addition, this newly developed genetically encoded bapaUGAc sensor will be a valuable tool for studying UDP-GlcNAc and glycobiology.
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Affiliation(s)
- Jing Zhang
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, 1340 Jefferson Park Ave, Charlottesville, Virginia, 22908, USA
- Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, Virginia, 22908, USA
| | - Zefan Li
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, 1340 Jefferson Park Ave, Charlottesville, Virginia, 22908, USA
- Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, Virginia, 22908, USA
| | - Yu Pang
- Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, Virginia, 22908, USA
- Department of Chemistry, University of Virginia, Charlottesville, Virginia, 22904, USA
| | - Yichong Fan
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, 1340 Jefferson Park Ave, Charlottesville, Virginia, 22908, USA
- Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, Virginia, 22908, USA
| | - Hui-wang Ai
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, 1340 Jefferson Park Ave, Charlottesville, Virginia, 22908, USA
- Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, Virginia, 22908, USA
- Department of Chemistry, University of Virginia, Charlottesville, Virginia, 22904, USA
- UVA Comprehensive Cancer Center, University of Virginia, Charlottesville, Virginia, 22903, USA
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Li L, Guan W, Zhang G, Wu Z, Yu H, Chen X, Wang PG. Microarray analyses of closely related glycoforms reveal different accessibilities of glycan determinants on N-glycan branches. Glycobiology 2020; 30:334-345. [PMID: 32026940 PMCID: PMC7175966 DOI: 10.1093/glycob/cwz100] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 11/27/2019] [Accepted: 12/02/2019] [Indexed: 01/03/2023] Open
Abstract
Glycans mediate a wide variety of biological roles via recognition by glycan-binding proteins (GBPs). Comprehensive knowledge of such interaction is thus fundamental to glycobiology. While the primary binding feature of GBPs can be easily uncovered by using a simple glycan microarray harboring limited numbers of glycan motifs, their fine specificities are harder to interpret. In this study, we prepared 98 closely related N-glycoforms that contain 5 common glycan epitopes which allowed the determination of the fine binding specificities of several plant lectins and anti-glycan antibodies. These N-glycoforms differ from each other at the monosaccharide level and were presented in an identical format to ensure comparability. With the analysis platform we used, it was found that most tested GBPs have preferences toward only one branch of the complex N-glycans, and their binding toward the epitope-presenting branch can be significantly affected by structures on the other branch. Fine specificities described here are valuable for a comprehensive understanding and applications of GBPs.
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Affiliation(s)
- Lei Li
- Department of Chemistry, Georgia State University, Atlanta, GA 30303, USA
| | - Wanyi Guan
- Department of Chemistry, Georgia State University, Atlanta, GA 30303, USA
| | - Gaolan Zhang
- Department of Chemistry, Georgia State University, Atlanta, GA 30303, USA
| | - Zhigang Wu
- Department of Chemistry, Georgia State University, Atlanta, GA 30303, USA
| | - Hai Yu
- Department of Chemistry, Georgia State University, Atlanta, GA 30303, USA
| | - Xi Chen
- Department of Chemistry, University of California, One Shields Avenue, Davis, CA, 95616, USA
| | - Peng G Wang
- Department of Chemistry, Georgia State University, Atlanta, GA 30303, USA
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5
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Heterologous expression, purification and characterization of human β-1,2-N-acetylglucosaminyltransferase II using a silkworm-based Bombyx mori nucleopolyhedrovirus bacmid expression system. J Biosci Bioeng 2018; 126:15-22. [DOI: 10.1016/j.jbiosc.2018.01.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2017] [Revised: 01/09/2018] [Accepted: 01/15/2018] [Indexed: 01/21/2023]
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6
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Restuccia A, Hudalla GA. Tuning carbohydrate density enhances protein binding and inhibition by glycosylated β-sheet peptide nanofibers. Biomater Sci 2018; 6:2327-2335. [DOI: 10.1039/c8bm00533h] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The efficacy of glycosylated β-sheet peptide nanofibers for inhibiting carbohydrate-binding proteins can be increased by tuning carbohydrate density to maximize protein binding affinity.
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Affiliation(s)
- Antonietta Restuccia
- J. Crayton Pruitt Family Department of Biomedical Engineering
- University of Florida
- Gainesville
- USA 32611
| | - Gregory A. Hudalla
- J. Crayton Pruitt Family Department of Biomedical Engineering
- University of Florida
- Gainesville
- USA 32611
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Lectin binding studies on a glycopolymer brush flow-through biosensor by localized surface plasmon resonance. Anal Bioanal Chem 2016; 408:5633-40. [DOI: 10.1007/s00216-016-9667-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Revised: 05/20/2016] [Accepted: 05/25/2016] [Indexed: 01/01/2023]
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8
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Park H, Walta S, Rosencrantz RR, Körner A, Schulte C, Elling L, Richtering W, Böker A. Micelles from self-assembled double-hydrophilic PHEMA-glycopolymer-diblock copolymers as multivalent scaffolds for lectin binding. Polym Chem 2016. [DOI: 10.1039/c5py00797f] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We introduce a novel double-hydrophilic hydroxyethylmethacrylate (HEMA) based diblock glycopolymer which self-assembles into homogeneous spherical micellar structures in water.
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Affiliation(s)
- H. Park
- DWI – Leibniz Institut für Interaktive Materialien e.V
- Lehrstuhl für Makromolekulare Materialien und Oberflächen
- Aachen
- Germany
| | - S. Walta
- Institute of Physical Chemistry
- RWTH Aachen University
- JARA – Soft Matter Science
- D-52074 Aachen
- Germany
| | - R. R. Rosencrantz
- Laboratory for Biomaterials
- Institute for Biotechnology and Helmholtz-Institute for Biomedical Engineering
- RWTH Aachen University
- 52074 Aachen
- Germany
| | - A. Körner
- DWI – Leibniz Institut für Interaktive Materialien e.V
- Lehrstuhl für Makromolekulare Materialien und Oberflächen
- Aachen
- Germany
| | - C. Schulte
- Fraunhofer-Institut für Angewandte Polymerforschung
- Lehrstuhl für Polymermaterialien und Polymertechnologie
- Universität Potsdam
- 14476 Potsdam-Golm
- Germany
| | - L. Elling
- Laboratory for Biomaterials
- Institute for Biotechnology and Helmholtz-Institute for Biomedical Engineering
- RWTH Aachen University
- 52074 Aachen
- Germany
| | - W. Richtering
- Institute of Physical Chemistry
- RWTH Aachen University
- JARA – Soft Matter Science
- D-52074 Aachen
- Germany
| | - A. Böker
- DWI – Leibniz Institut für Interaktive Materialien e.V
- Lehrstuhl für Makromolekulare Materialien und Oberflächen
- Aachen
- Germany
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9
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Mammalian Cell Surface Display as a Novel Method for Developing Engineered Lectins with Novel Characteristics. Biomolecules 2015; 5:1540-62. [PMID: 26287256 PMCID: PMC4598763 DOI: 10.3390/biom5031540] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2015] [Revised: 06/16/2015] [Accepted: 06/18/2015] [Indexed: 01/13/2023] Open
Abstract
Leguminous lectins have a conserved carbohydrate recognition site comprising four loops (A–D). Here, we randomly mutated the sequence and length of loops C and D of peanut agglutinin (PNA) and expressed the proteins on the surface of mouse green fluorescent protein (GFP)-reporter cells. Flow cytometry, limiting dilution, and cDNA cloning were used to screen for several mutated PNAs with distinct properties. The mutated PNA clones obtained using NeuAcα2-6(Galβ1-3)GalNAc as a ligand showed preference for NeuAcα2-6(Galβ1-3)GalNAc rather than non-sialylated Galβ1-3GlcNAc, whereas wild-type PNA binds to Galβ1-3GlcNAc but not sialylated Galβ1-3GalNAc. Sequence analyses revealed that for all of the glycan-reactive mutated PNA clones, (i) loop C was eight amino acids in length, (ii) loop D was identical to that of wild-type PNA, (iii) residue 127 was asparagine, (iv) residue 125 was tryptophan, and (v) residue 130 was hydrophobic tyrosine, phenylalanine, or histidine. The sugar-binding ability of wild-type PNA was increased nine-fold when Tyr125 was mutated to tryptophan, and that of mutated clone C was increased more than 30-fold after His130 was changed to tyrosine. These results provide an insight into the relationship between the amino acid sequences of the carbohydrate recognition site and sugar-binding abilities of leguminous lectins.
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Lazar J, Park H, Rosencrantz RR, Böker A, Elling L, Schnakenberg U. Evaluating the Thickness of Multivalent Glycopolymer Brushes for Lectin Binding. Macromol Rapid Commun 2015; 36:1472-8. [DOI: 10.1002/marc.201500118] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Revised: 05/19/2015] [Indexed: 11/07/2022]
Affiliation(s)
- Jaroslav Lazar
- Institute of Materials in Electrical Engineering 1; RWTH Aachen University; Sommerfeldstr. 24 52074 Aachen Germany
| | - Hyunji Park
- DWI-Leibniz Institut für Interaktive Materialien e.V; Lehrstuhl für Makromolekulare Materialien und Oberflächen; Forckenbeckstr. 50 52074 Aachen Germany
| | - Ruben R. Rosencrantz
- Laboratory for Biomaterials Institute for Biotechnology and Helmholtz-Institute for Biomedical Engineering; RWTH Aachen University; Pauwelsstr. 20 52074 Aachen Germany
| | - Alexander Böker
- DWI-Leibniz Institut für Interaktive Materialien e.V; Lehrstuhl für Makromolekulare Materialien und Oberflächen; Forckenbeckstr. 50 52074 Aachen Germany
| | - Lothar Elling
- Laboratory for Biomaterials Institute for Biotechnology and Helmholtz-Institute for Biomedical Engineering; RWTH Aachen University; Pauwelsstr. 20 52074 Aachen Germany
| | - Uwe Schnakenberg
- Institute of Materials in Electrical Engineering 1; RWTH Aachen University; Sommerfeldstr. 24 52074 Aachen Germany
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Suggestive evidence for Darwinian Selection against asparagine-linked glycans of Plasmodium falciparum and Toxoplasma gondii. EUKARYOTIC CELL 2009; 9:228-41. [PMID: 19783771 DOI: 10.1128/ec.00197-09] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
We are interested in asparagine-linked glycans (N-glycans) of Plasmodium falciparum and Toxoplasma gondii, because their N-glycan structures have been controversial and because we hypothesize that there might be selection against N-glycans in nucleus-encoded proteins that must pass through the endoplasmic reticulum (ER) prior to threading into the apicoplast. In support of our hypothesis, we observed the following. First, in protists with apicoplasts, there is extensive secondary loss of Alg enzymes that make lipid-linked precursors to N-glycans. Theileria makes no N-glycans, and Plasmodium makes a severely truncated N-glycan precursor composed of one or two GlcNAc residues. Second, secreted proteins of Toxoplasma, which uses its own 10-sugar precursor (Glc(3)Man(5)GlcNAc(2)) and the host 14-sugar precursor (Glc(3)Man(9)GlcNAc(2)) to make N-glycans, have very few sites for N glycosylation, and there is additional selection against N-glycan sites in its apicoplast-targeted proteins. Third, while the GlcNAc-binding Griffonia simplicifolia lectin II labels ER, rhoptries, and surface of plasmodia, there is no apicoplast labeling. Similarly, the antiretroviral lectin cyanovirin-N, which binds to N-glycans of Toxoplasma, labels ER and rhoptries, but there is no apicoplast labeling. We conclude that possible selection against N-glycans in protists with apicoplasts occurs by eliminating N-glycans (Theileria), reducing their length (Plasmodium), or reducing the number of N-glycan sites (Toxoplasma). In addition, occupation of N-glycan sites is markedly reduced in apicoplast proteins versus some secretory proteins in both Plasmodium and Toxoplasma.
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Macedo MLR, de Castro MM, Freire MDGM. Mechanisms of the insecticidal action of TEL (Talisia esculenta lectin) against Callosobruchus maculatus (Coleoptera: Bruchidae). ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2004; 56:84-96. [PMID: 15146543 DOI: 10.1002/arch.10145] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Plant lectins have insecticidal activity that is probably mediated through their ability to bind carbohydrates. To examine the influence of sugars on the insecticidal activity of a lectin from Talisia esculenta seeds (TEL), the lectin was mixed with mannose, glucose, or mannose plus glucose. Mannose abolished the insecticidal activity. Affinity chromatography showed that TEL bound to midgut proteins of the insect Callosobruchus maculatus. Immunoblotting showed that TEL recognized some proteins, probably glycoproteins, present in the midgut membrane of this insect. The principal proteases responsible for digestive proteolysis in fourth instar larvae of C. maculatus were purified by chromatography on activated thiol-Sepharose. These purified proteases were unable to digest TEL after a 15-h incubation. These results suggest that the insecticidal activity of TEL involves a specific carbohydrate-lectin interaction with glycoconjugates on the surface of digestive tract epithelial cells, as well as binding to assimilatory glycoproteins present in midgut extracts and resistance to enzymatic digestion by cysteine proteinases.
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Affiliation(s)
- Maria Lígia Rodrigues Macedo
- Laboratório de Purificação de Proteínas e suas Funções Biológicas, Departamento de Ciências Naturais, Universidade Federal de Mato Grosso do Sul, Três Lagoas, MS, Brazil
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13
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Leach MR, Williams DB. Lectin-deficient Calnexin Is Capable of Binding Class I Histocompatibility Molecules in Vivo and Preventing Their Degradation. J Biol Chem 2004; 279:9072-9. [PMID: 14699098 DOI: 10.1074/jbc.m310788200] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Calnexin is a membrane-bound lectin of the endoplasmic reticulum (ER) that binds transiently to newly synthesized glycoproteins. By interacting with oligosaccharides of the form Glc(1)Man(9)GlcNAc(2), calnexin enhances the folding of glycoprotein substrates, retains misfolded variants in the ER, and in some cases participates in their degradation. Calnexin has also been shown to bind polypeptides in vivo that do not possess a glycan of this form and to function in vitro as a molecular chaperone for nonglycosylated proteins. To test the relative importance of the lectin site compared with the polypeptide-binding site, we have generated six calnexin mutants defective in oligosaccharide binding using site-directed mutagenesis. Expressed as glutathione S-transferase fusions, these mutants were still capable of binding ERp57, a thiol oxidoreductase, and preventing the aggregation of a nonglycosylated substrate, citrate synthase. They were, however, unable to bind Glc(1) Man(9)GlcNAc(2) oligosaccharide and were compromised in preventing the aggregation of the monoglucosylated substrate jack bean alpha-mannosidase. Two of these mutants were then engineered into full-length calnexin for heterologous expression in Drosophila cells along with the murine class I histocompatibility molecules K(b) and D(b) as model glycoproteins. In this system, lectin site-defective calnexin was able to replace wild type calnexin in forming a complex with K(b) and D(b) heavy chains and preventing their degradation. Thus, at least for class I molecules, the lectin site of calnexin is dispensable for some of its chaperone functions.
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Affiliation(s)
- Michael R Leach
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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14
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Affiliation(s)
- Hansjörg Streicher
- Department of Chemistry, University of Konstanz, Konstanz D-78457, Germany
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15
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Zhu-Salzman K, Hammen PK, Salzman RA, Koiwa H, Bressan RA, Murdock LL, Hasegawa PM. Calcium modulates protease resistance and carbohydrate binding of a plant defense legume lectin, Griffonia simplicifolia lectin II (GSII). Comp Biochem Physiol B Biochem Mol Biol 2002; 132:327-34. [PMID: 12031457 DOI: 10.1016/s1096-4959(02)00033-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Site-directed mutagenesis previously identified the residues responsible for the biological activity of the plant defense legume lectin, Griffonia simplicifolia lectin II (GSII) [Proc. Natl. Acad. Sci. USA 95, (1998) 15123-15128]. However, these results were inconclusive as to whether these residues function as direct defense determinants through carbohydrate binding, or whether substantial changes of the protein structure had occurred in mutated proteins, with this structural disruption actually causing the loss of biochemical and biological functions. Evidence shown here supports the former explanation: circular dichroism and fluorescence spectra showed that mutations at carbohydrate-binding residues of GSII do not render it dysfunctional because of substantial secondary or tertiary structure modifications; and trypsin treatment confirmed that rGSII structural integrity is retained in these mutants. Reduced biochemical stability was observed through papain digestion and urea denaturation in mutant versions that had lost carbohydrate-binding ability, and this was correlated with lower Ca(2+) content. Accordingly, the re-addition of Ca(2+) to demetalized proteins could recover resistance to papain in the carbohydrate-binding mutant, but not in the non-binding mutant. Thus, both carbohydrate binding (presumably to targets in the insect gut) and biochemical stability to proteolytic degradation in situ indeed contribute to anti-insect activity, and these activities are Ca(2+)-dependent.
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Affiliation(s)
- Keyan Zhu-Salzman
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA.
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16
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Zhu-Salzman K, Salzman RA. Functional mechanics of the plant defensive Griffonia simplicifolia lectin II: resistance to proteolysis is independent of glycoconjugate binding in the insect gut. JOURNAL OF ECONOMIC ENTOMOLOGY 2001; 94:1280-1284. [PMID: 11681694 DOI: 10.1603/0022-0493-94.5.1280] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Griffonia simplicifolia lectin II (GSII) is a plant defensive protein that significantly delays development of the cowpea bruchid Callosobruchus maculatus (F.). Previous structure/function analysis by site-directed mutagenesis indicated that carbohydrate binding and resistance to insect gut proteolysis are required for the anti-insect activity of this lectin. However, whether there is a causal link between carbohydrate binding and resistance to insect metabolism remains unknown. Two proteases principally responsible for digestive proteolysis in third and fourth instar larvae of C. maculatus were purified by activated thiol sepharose chromatography and resolved as cathepsin L-like proteases, based on N-terminal amino acid sequence analysis. Digestion of bacterially expressed recombinant GSII (rGSII) and its mutant protein variants with the purified gut proteases indicates that carbohydrate binding, presumably to a target ligand in insect gut, and proteolytic resistance are independent properties of rGSII, and that both facilitate its efficacy as a plant defensive molecule.
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Affiliation(s)
- K Zhu-Salzman
- Institute for Plant Genomics and Biotechnology, Texas A&M University, College Station, TX 77843, USA.
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Wang S, Regnier FE. Proteomics based on selecting and quantifying cysteine containing peptides by covalent chromatography. J Chromatogr A 2001; 924:345-57. [PMID: 11521884 DOI: 10.1016/s0021-9673(01)00961-x] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
This paper describes a procedure in which cysteine containing peptides from tryptic digests of complex protein mixtures were selected by covalent chromatography based on thiol-disulfide exchange. identified by mass spectrometry, and quantified by differential isotope labeling. Following disruption of disulfide bridges with 2,2'-dipyridyl disulfide, all proteins were digested with trypsin and acylated with succinic anhydride. Cysteine containing peptides were then selected from the acylated digest by disulfide interchange with sulfhydryl groups on a thiopropyl Sepharose gel. Captured cysteine containing peptides were released from the gel with 25 mM dithiothreitol (pH 7.5) containing 1 mM (ethylenedinitrilo)tetraacetic acid disodium salt and alkylated with iodoacetic acid subsequent to fractionation by reversed-phase liquid chromatography (RPLC). Fractions collected from the RPLC column were analyzed by matrix-assisted laser desorption ionization mass spectrometry. Based on isotope ratios of peptides from experimental and control samples labeled with succinic and deuterated succinic anhydride, respectively, it was possible to determine the relative concentration of each peptide species between the two samples. Peptides obtained from proteins that were up-regulated in the experimental sample were easily identified by an increase of the relative amount of the deuterated peptide. The results of these studies indicate that by selecting cysteine containing peptides, the complexity of protein digest could be reduced and database searches greatly simplified. When coupled with the isotope labeling strategy for quantification it was possible to determine proteins that were up-regulated in plasmid bearing Escherichia coli when expression of plasmid proteins was induced. Up-regulation of several proteins of E. coli origin was also noted.
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Affiliation(s)
- S Wang
- Department of Chemistry, Purdue University, Lafayette, IN 47907, USA
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Roche AC, Monsigny M. MR60/ERGIC-53, a mannose-specific shuttling intracellular membrane lectin. Results Probl Cell Differ 2001; 33:19-38. [PMID: 11190675 DOI: 10.1007/978-3-540-46410-5_2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- A C Roche
- Centre de Biophysique Moléculaire, CNRS and University of Orléans, Rue Charles Sadron 45071 Orléans, France
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Loris R, De Greve H, Dao-Thi MH, Messens J, Imberty A, Wyns L. Structural basis of carbohydrate recognition by lectin II from Ulex europaeus, a protein with a promiscuous carbohydrate-binding site. J Mol Biol 2000; 301:987-1002. [PMID: 10966800 DOI: 10.1006/jmbi.2000.4016] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Protein-carbohydrate interactions are the language of choice for inter- cellular communication. The legume lectins form a large family of homologous proteins that exhibit a wide variety of carbohydrate specificities. The legume lectin family is therefore highly suitable as a model system to study the structural principles of protein-carbohydrate recognition. Until now, structural data are only available for two specificity families: Man/Glc and Gal/GalNAc. No structural data are available for any of the fucose or chitobiose specific lectins. The crystal structure of Ulex europaeus (UEA-II) is the first of a legume lectin belonging to the chitobiose specificity group. The complexes with N-acetylglucosamine, galactose and fucosylgalactose show a promiscuous primary binding site capable of accommodating both N-acetylglucos amine or galactose in the primary binding site. The hydrogen bonding network in these complexes can be considered suboptimal, in agreement with the low affinities of these sugars. In the complexes with chitobiose, lactose and fucosyllactose this suboptimal hydrogen bonding network is compensated by extensive hydrophobic interactions in a Glc/GlcNAc binding subsite. UEA-II thus forms the first example of a legume lectin with a promiscuous binding site and illustrates the importance of hydrophobic interactions in protein-carbohydrate complexes. Together with other known legume lectin crystal structures, it shows how different specificities can be grafted upon a conserved structural framework.
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Affiliation(s)
- R Loris
- Laboratorium voor Ultrastruktuur, Vlaams Interuniversitair Instituut voor Biotechnologie, Vrije Universiteit Brussel, Paardenstraat 65, Sint-Genesius-Rode, B-1640, Belgium.
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Zhu-Salzman K, Shade RE, Koiwa H, Salzman RA, Narasimhan M, Bressan RA, Hasegawa PM, Murdock LL. Carbohydrate binding and resistance to proteolysis control insecticidal activity of Griffonia simplicifolia lectin II. Proc Natl Acad Sci U S A 1998; 95:15123-8. [PMID: 9844026 PMCID: PMC24586 DOI: 10.1073/pnas.95.25.15123] [Citation(s) in RCA: 99] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Griffonia simplicifolia leaf lectin II (GSII), a plant defense protein against certain insects, consists of an N-acetylglucosamine (GlcNAc)-binding large subunit with a small subunit having sequence homology to class III chitinases. Much of the insecticidal activity of GSII is attributable to the large lectin subunit, because bacterially expressed recombinant large subunit (rGSII) inhibited growth and development of the cowpea bruchid, Callosobruchus maculatus (F). Site-specific mutations were introduced into rGSII to generate proteins with altered GlcNAc binding, and the different rGSII proteins were evaluated for insecticidal activity when added to the diet of the cowpea bruchid. At pH 5.5, close to the physiological pH of the cowpea bruchid midgut lumen, rGSII recombinant proteins were categorized as having high (rGSII, rGSII-Y134F, and rGSII-N196D mutant proteins), low (rGSII-N136D), or no (rGSII-D88N, rGSII-Y134G, rGSII-Y134D, and rGSII-N136Q) GlcNAc-binding activity. Insecticidal activity of the recombinant proteins correlated with their GlcNAc-binding activity. Furthermore, insecticidal activity correlated with the resistance to proteolytic degradation by cowpea bruchid midgut extracts and with GlcNAc-specific binding to the insect digestive tract. Together, these results establish that insecticidal activity of GSII is functionally linked to carbohydrate binding, presumably to the midgut epithelium or the peritrophic matrix, and to biochemical stability of the protein to digestive proteolysis.
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Affiliation(s)
- K Zhu-Salzman
- Department of Entomology, Purdue University, West Lafayette, IN 47907, USA
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Lis H, Sharon N. Lectins: Carbohydrate-Specific Proteins That Mediate Cellular Recognition. Chem Rev 1998; 98:637-674. [PMID: 11848911 DOI: 10.1021/cr940413g] [Citation(s) in RCA: 1289] [Impact Index Per Article: 49.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Halina Lis
- Department of Membrane Research and Biophysics, The Weizmann Institute of Science, Rehovot 76100, Israel
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Abstract
The legume lectins are a large family of homologous carbohydrate binding proteins that are found mainly in the seeds of most legume plants. Despite their strong similarity on the level of their amino acid sequences and tertiary structures, their carbohydrate specificities and quaternary structures vary widely. In this review we will focus on the structural features of legume lectins and their complexes with carbohydrates. These will be discussed in the light of recent mutagenesis results when appropriate. Monosaccharide specificity seems to be achieved by the use of a conserved core of residues that hydrogen bond to the sugar, and a variable loop that determines the exact shape of the monosaccharide binding site. The higher affinity for particular oligosaccharides and monosaccharides containing a hydrophobic aglycon results mainly from a few distinct subsites next to the monosaccharide binding site. These subsites consist of a small number of variable residues and are found in both the mannose and galactose specificity groups. The quaternary structures of these proteins form the basis of a higher level of specificity, where the spacing between individual epitopes of multivalent carbohydrates becomes important. This results in homogeneous cross-linked lattices even in mixed precipitation systems, and is of relevance for their effects on the biological activities of cells such as mitogenic responses. Quaternary structure is also thought to play an important role in the high affinity interaction between some legume lectins and adenine and a series of adenine-derived plant hormones. The molecular basis of the variation in quaternary structure in this group of proteins is poorly understood.
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Affiliation(s)
- R Loris
- Laboratorium voor Ultrastruktuur, Vlaams Interuniversitair Instituut voor Biotechnologie, Vrije Universiteit Brussel, Sint-Genesius-Rode, Belgium.
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