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Anne Imberty - One of the best experts on this subject based on the ideXlab platform.
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binding sugars from natural lectins to synthetic receptors and engineered neolectins
2013Co-Authors: Julie Arnaud, Aymeric Audfray, Anne ImbertyAbstract:The large diversity and complexity of glycan structures together with their crucial role in many biological or pathological processes require the development of new high-throughput techniques for analyses. Lectins are classically used for characterising, imaging or targeting glycoconjugates and, when printed on microarrays, they are very useful tools for profiling glycomes. Development of recombinant lectins gives access to reliable and reproducible material, while engineering of new binding sites on existing scaffolds allows tuning of specificity. From the accumulated knowledge on protein–carbohydrate Interactions, it is now possible to use nucleotide and peptide (bio)synthesis for producing new carbohydrate-binding molecules. Such a biomimetic approach can also be addressed by boron chemistry and supra-molecular chemistry for the design of fully artificial glycosensors.
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multivalent gold glycoclusters high affinity molecular recognition by bacterial lectin pa il
2012Co-Authors: Anne Imberty, Serge Perez, Michael Reynolds, Marco Marradi, Soledad PenadesAbstract:Multivalent Protein-Carbohydrate Interactions are involved in the initial stages of many fundamental biological and pathological processes through lectin-carbohydrate binding. The design of high affinity ligands is therefore necessary to study, inhibit and control the processes governed through carbohydrate recognition by their lectin receptors. Carbohydrate-functionalised gold nanoclusters (glyconanoparticles, GNPs) show promising potential as multivalent tools for studies in fundamental glycobiology research as well as biomedical applications. Here we present the synthesis and characterisation of galactose functionalised GNPs and their effectiveness as binding partners for PA-IL lectin from Pseudomonas aeruginosa. Interactions were evaluated by hemagglutination inhibition (HIA), surface plasmon resonance (SPR) and isothermal titration calorimetry (ITC) assays. Results show that the gold nanoparticle platform displays a significant cluster glycoside effect for presenting carbohydrate ligands with almost a 3000-fold increase in binding compared with a monovalent reference probe in free solution. The most effective GNP exhibited a dissociation constant (K(d)) of 50 nM per monosaccharide, the most effective ligand of PA-IL measured to date; another demonstration of the potential of glyco-nanotechnology towards multivalent tools and potent anti-adhesives for the prevention of pathogen invasion. The influence of ligand presentation density on their recognition by protein receptors is also demonstrated.
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The fucose-binding lectin from Ralstonia solanacearum. A new type of beta-propeller architecture formed by oligomerization and interacting with fucoside, fucosyllactose, and plant xyloglucan.
2005Co-Authors: Nikola Kostlanova, Martina Lahmann, Stefan Oscarson, Nechama Gilboa-garber, Hugues Lortat-jacob, Edward P Mitchell, Michaela Wimmerova, Gérard Chambat, Anne ImbertyAbstract:Plant pathogens, like animal ones, use Protein-Carbohydrate Interactions in their strategy for host recognition, attachment, and invasion. The bacterium Ralstonia solanacearum, which is distributed worldwide and causes lethal wilt in many agricultural crops, was shown to produce a potent L-fucose-binding lectin, R. solanacearum lectin, a small protein of 90 amino acids with a tandem repeat in its amino acid sequence. In the present study, surface plasmon resonance experiments conducted on a series of oligosaccharides show a preference for binding to alphaFuc1-2Gal and alphaFuc1-6Gal epitopes. Titration microcalorimetry demonstrates the presence of two binding sites per monomer and an unusually high affinity of the lectin for alphaFuc1-2Gal-containing oligosaccharides (KD = 2.5 x 10(-7) M for 2-fucosyllactose). R. solanacearum lectin has been crystallized with a methyl derivative of fucose and with the highest affinity ligand, 2-fucosyllactose. X-ray crystal structures, the one with alpha-methyl-fucoside being at ultrahigh resolution, reveal that each monomer consists of two small four-stranded anti-parallel beta-sheets. Trimerization through a 3-fold or pseudo-3-fold axis generates a six-bladed beta-propeller architecture, very similar to that previously described for the fungal lectin of Aleuria aurantia. This is the first report of a beta-propeller formed by oligomerization and not by sequential domains. Each monomer presents two fucose binding sites, resulting in six symmetrically arranged sugar binding sites for the beta-propeller. Crystals were also obtained for a mutated lectin complexed with a fragment of xyloglucan, a fucosylated polysaccharide from the primary cell wall of plants, which may be the biological target of the lectin.
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Structural basis of carbohydrate recognition by lectin II from Ulex europaeus, a protein with a promiscuous carbohydrate-binding site.
2000Co-Authors: Remy Loris, Anne Imberty, H. De Greve, Joris Messens, Lode WynsAbstract: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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molecular modelling of protein carbohydrate Interactions understanding the specificities of two legume lectins towards oligosaccharides
1994Co-Authors: Anne Imberty, Serge PerezAbstract:: By means of a series of new molecular modelling tools, the conformational behaviour of mannose-containing di- and trisaccharides bound to either concanavalin A or Lathyrus ochrus isolectin I (LOLI) has been assessed. Tools for estimating and analysing either the 'rigid' or the 'relaxed' potential energy surfaces, representing the conformational space available for carbohydrates once interacting with lectins, are reported for the first time. Restrictions of conformational space are predicted to occur with different magnitudes, depending on the nature of the glycosidic linkages, as well as the size of the carbohydrates. Results from these molecular modelling studies are compared to existing structural data. Not only could the observed conformations and orientations of carbohydrates in crystalline lectin-oligosaccharides complexes be reproduced, but several other likely situations were also predicted to occur. Entropy calculations have been performed for comparison with experimental thermodynamics data. The results of the stimulation can also help giving an explanation of some observed affinity constants at the molecular level.
Kelley W. Moremen - One of the best experts on this subject based on the ideXlab platform.
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structure of mouse golgi alpha mannosidase ia reveals the molecular basis for substrate specificity among class 1 family 47 glycosylhydrolase alpha1 2 mannosidases
2004Co-Authors: Wolfram Tempel, Khanita Karaveg, J P Rose, B. C. Wang, Kelley W. MoremenAbstract:Abstract Three subfamilies of mammalian Class 1 processing α1,2-mannosidases (family 47 glycosidases) play critical roles in the maturation of Asn-linked glycoproteins in the endoplasmic reticulum (ER) and Golgi complex as well as influencing the timing and recognition for disposal of terminally unfolded proteins by ER-associated degradation. In an effort to define the structural basis for substrate recognition among Class 1 mannosidases, we have crystallized murine Golgi mannosidase IA (space group P212121), and the structure was solved to 1.5-A resolution by molecular replacement. The enzyme assumes an (αα)7 barrel structure with a Ca2+ ion coordinated at the base of the barrel similar to other Class 1 mannosidases. Critical residues within the barrel structure that coordinate the Ca2+ ion or presumably bind and catalyze the hydrolysis of the glycone are also highly conserved. A Man6GlcNAc2 oligosaccharide attached to Asn515 in the murine enzyme was found to extend into the active site of an adjoining protein unit in the crystal lattice in a presumed enzyme-product complex. In contrast to an analogous complex previously isolated for Saccharomyces cerevisiae ER mannosidase I, the oligosaccharide in the active site of the murine Golgi enzyme assumes a different conformation to present an alternate oligosaccharide branch into the active site pocket. A comparison of the observed Protein-Carbohydrate Interactions for the murine Golgi enzyme with the binding cleft topologies of the other family 47 glycosidases provides a framework for understanding the structural basis for substrate recognition among this class of enzymes.
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structure of mouse golgi alpha mannosidase ia reveals the molecular basis for substrate specificity among class 1 family 47 glycosylhydrolase alpha1 2 mannosidases
2004Co-Authors: Wolfram Tempel, Khanita Karaveg, J P Rose, B. C. Wang, Kelley W. MoremenAbstract:Abstract Three subfamilies of mammalian Class 1 processing α1,2-mannosidases (family 47 glycosidases) play critical roles in the maturation of Asn-linked glycoproteins in the endoplasmic reticulum (ER) and Golgi complex as well as influencing the timing and recognition for disposal of terminally unfolded proteins by ER-associated degradation. In an effort to define the structural basis for substrate recognition among Class 1 mannosidases, we have crystallized murine Golgi mannosidase IA (space group P212121), and the structure was solved to 1.5-A resolution by molecular replacement. The enzyme assumes an (αα)7 barrel structure with a Ca2+ ion coordinated at the base of the barrel similar to other Class 1 mannosidases. Critical residues within the barrel structure that coordinate the Ca2+ ion or presumably bind and catalyze the hydrolysis of the glycone are also highly conserved. A Man6GlcNAc2 oligosaccharide attached to Asn515 in the murine enzyme was found to extend into the active site of an adjoining protein unit in the crystal lattice in a presumed enzyme-product complex. In contrast to an analogous complex previously isolated for Saccharomyces cerevisiae ER mannosidase I, the oligosaccharide in the active site of the murine Golgi enzyme assumes a different conformation to present an alternate oligosaccharide branch into the active site pocket. A comparison of the observed Protein-Carbohydrate Interactions for the murine Golgi enzyme with the binding cleft topologies of the other family 47 glycosidases provides a framework for understanding the structural basis for substrate recognition among this class of enzymes.
Els J. M. Van Damme - One of the best experts on this subject based on the ideXlab platform.
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glycan arrays to decipher the specificity of plant lectins
2011Co-Authors: Els J. M. Van Damme, David F Smith, Richard D. CummingsAbstract:In recent years, evidence has been accumulating that protein–carbohydrate Interactions play an important role in host–pathogen interaction(s), development, cell–cell communication, and cell signaling. To study the protein–carbohydrate recognition phenomena that take place within or at the surface of a cell, it is requisite to have the appropriate tools for dissecting this type of interaction. During the past decade, microarray technology has successfully been introduced into the field of glycobiology. These carbohydrate or glycan microarrays allow the rapid and comprehensive screening of carbohydrate-binding proteins for interaction with a large set of carbohydrate structures and characterization of their carbohydrate-binding properties.
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nucleocytoplasmic plant lectins
2010Co-Authors: Nausicaa Lannoo, Els J. M. Van DammeAbstract:During the last decade it was unambiguously shown that plants synthesize minute amounts of carbohydrate-binding proteins upon exposure to stress situations like drought, high salt, hormone treatment, pathogen attack or insect herbivory. In contrast to the 'classical' plant lectins, which are typically found in storage vacuoles or in the extracellular compartment this new class of lectins is located in the cytoplasm and the nucleus. Based on these observations the concept was developed that lectin-mediated Protein-Carbohydrate Interactions in the cytoplasm and the nucleus play an important role in the stress physiology of the plant cell. Hitherto, six families of nucleocytoplasmic lectins have been identified. This review gives an overview of our current knowledge on the occurrence of nucleocytoplasmic plant lectins. The carbohydrate-binding properties of these lectins and potential ligands in the nucleocytoplasmic compartment are discussed in view of the physiological role of the lectins in the plant cell.
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cytoplasmic nuclear plant lectins a new story
2004Co-Authors: Els J. M. Van Damme, Annick Barre, Pierre Rougé, Willy J PeumansAbstract:Plant lectins comprise a widespread group of carbohydrate-binding proteins that show a marked heterogeneity with respect to their molecular structure, sugar-binding specificity and temporal and spatial regulation. Until recently, the role of most lectins was associated with their binding to foreign glycans in either recognition and/or defence-related phenomena. Over the past few years, evidence has accumulated to support the idea that when plants are stimulated by specific biotic or abiotic stimuli they respond through the expression of cytoplasmic and/or nuclear plant lectins. The location and the regulation of the expression of these lectins indicate that lectins are involved in specific endogenous protein–carbohydrate Interactions. These novel findings led to the challenging idea that lectins might be involved in cellular regulation and signalling.
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the identification of inducible cytoplasmic nuclear carbohydrate binding proteins urges to develop novel concepts about the role of plant lectins
2003Co-Authors: Els J. M. Van Damme, Nausicaa Lannoo, Elke Fouquaert, Willy J PeumansAbstract:During the last few years compelling evidence has been presented for the occurrence of cytoplasmic/nuclear plant lectins that are not detectable in normal plants but are only induced upon application of well-defined stress conditions. Since both the regulation of the expression and the subcellular location indicate that these ‘non-classical lectins’ are good candidates to play a physiologically important role as mediators of specific Protein-Carbohydrate-Interactions within the plant cell, a critical assessment is made of the impact of these findings on the development of novel concepts about the role of plant lectins. Based on an analysis of the biochemical, molecular and evolutionary data of a jasmonate-induced chitin-binding lectin from tobacco leaves and a salt/jasmonate-induced leaf lectin from rice it is concluded that these lectins most probably interact with endogenous glycans located within the cytoplasmic/nuclear compartment of the plant cell. Several working mechanisms are proposed to explain how these inducible lectins may fulfill an important regulatory or structural role in stressed cells. In addition, the question of the evolutionary relationship(s) between the newly discovered inducible lectins and their ‘classical’ constitutively expressed homologs is addressed. Evidence is presented that the ‘non-classical lectins’ represent the main evolutionary line and that some of their corresponding genes were used as templates for genes encoding storage protein-like ‘classical’ homologs. Published in 2004.
Serge Perez - One of the best experts on this subject based on the ideXlab platform.
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multivalent gold glycoclusters high affinity molecular recognition by bacterial lectin pa il
2012Co-Authors: Anne Imberty, Serge Perez, Michael Reynolds, Marco Marradi, Soledad PenadesAbstract:Multivalent Protein-Carbohydrate Interactions are involved in the initial stages of many fundamental biological and pathological processes through lectin-carbohydrate binding. The design of high affinity ligands is therefore necessary to study, inhibit and control the processes governed through carbohydrate recognition by their lectin receptors. Carbohydrate-functionalised gold nanoclusters (glyconanoparticles, GNPs) show promising potential as multivalent tools for studies in fundamental glycobiology research as well as biomedical applications. Here we present the synthesis and characterisation of galactose functionalised GNPs and their effectiveness as binding partners for PA-IL lectin from Pseudomonas aeruginosa. Interactions were evaluated by hemagglutination inhibition (HIA), surface plasmon resonance (SPR) and isothermal titration calorimetry (ITC) assays. Results show that the gold nanoparticle platform displays a significant cluster glycoside effect for presenting carbohydrate ligands with almost a 3000-fold increase in binding compared with a monovalent reference probe in free solution. The most effective GNP exhibited a dissociation constant (K(d)) of 50 nM per monosaccharide, the most effective ligand of PA-IL measured to date; another demonstration of the potential of glyco-nanotechnology towards multivalent tools and potent anti-adhesives for the prevention of pathogen invasion. The influence of ligand presentation density on their recognition by protein receptors is also demonstrated.
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thermodynamics and chemical characterization of protein carbohydrate Interactions the multivalency issue
2011Co-Authors: Michael Reynolds, Serge PerezAbstract:Abstract The present article reviews the thermodynamic models that are prevailing in the study of multivalent Interactions, which characterize protein–carbohydrate Interactions. The different classes of synthetic and semi-synthetic multivalent scaffolds that have been designed in view of understanding the intra- and intermolecular features are presented. This is followed by a critical appraisal of these various substructures as platforms for presenting carbohydrate ligands with respect to their influence on the cluster glycoside effect.
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molecular modelling of protein carbohydrate Interactions understanding the specificities of two legume lectins towards oligosaccharides
1994Co-Authors: Anne Imberty, Serge PerezAbstract:: By means of a series of new molecular modelling tools, the conformational behaviour of mannose-containing di- and trisaccharides bound to either concanavalin A or Lathyrus ochrus isolectin I (LOLI) has been assessed. Tools for estimating and analysing either the 'rigid' or the 'relaxed' potential energy surfaces, representing the conformational space available for carbohydrates once interacting with lectins, are reported for the first time. Restrictions of conformational space are predicted to occur with different magnitudes, depending on the nature of the glycosidic linkages, as well as the size of the carbohydrates. Results from these molecular modelling studies are compared to existing structural data. Not only could the observed conformations and orientations of carbohydrates in crystalline lectin-oligosaccharides complexes be reproduced, but several other likely situations were also predicted to occur. Entropy calculations have been performed for comparison with experimental thermodynamics data. The results of the stimulation can also help giving an explanation of some observed affinity constants at the molecular level.
Wolfram Tempel - One of the best experts on this subject based on the ideXlab platform.
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structure of mouse golgi alpha mannosidase ia reveals the molecular basis for substrate specificity among class 1 family 47 glycosylhydrolase alpha1 2 mannosidases
2004Co-Authors: Wolfram Tempel, Khanita Karaveg, J P Rose, B. C. Wang, Kelley W. MoremenAbstract:Abstract Three subfamilies of mammalian Class 1 processing α1,2-mannosidases (family 47 glycosidases) play critical roles in the maturation of Asn-linked glycoproteins in the endoplasmic reticulum (ER) and Golgi complex as well as influencing the timing and recognition for disposal of terminally unfolded proteins by ER-associated degradation. In an effort to define the structural basis for substrate recognition among Class 1 mannosidases, we have crystallized murine Golgi mannosidase IA (space group P212121), and the structure was solved to 1.5-A resolution by molecular replacement. The enzyme assumes an (αα)7 barrel structure with a Ca2+ ion coordinated at the base of the barrel similar to other Class 1 mannosidases. Critical residues within the barrel structure that coordinate the Ca2+ ion or presumably bind and catalyze the hydrolysis of the glycone are also highly conserved. A Man6GlcNAc2 oligosaccharide attached to Asn515 in the murine enzyme was found to extend into the active site of an adjoining protein unit in the crystal lattice in a presumed enzyme-product complex. In contrast to an analogous complex previously isolated for Saccharomyces cerevisiae ER mannosidase I, the oligosaccharide in the active site of the murine Golgi enzyme assumes a different conformation to present an alternate oligosaccharide branch into the active site pocket. A comparison of the observed Protein-Carbohydrate Interactions for the murine Golgi enzyme with the binding cleft topologies of the other family 47 glycosidases provides a framework for understanding the structural basis for substrate recognition among this class of enzymes.
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structure of mouse golgi alpha mannosidase ia reveals the molecular basis for substrate specificity among class 1 family 47 glycosylhydrolase alpha1 2 mannosidases
2004Co-Authors: Wolfram Tempel, Khanita Karaveg, J P Rose, B. C. Wang, Kelley W. MoremenAbstract:Abstract Three subfamilies of mammalian Class 1 processing α1,2-mannosidases (family 47 glycosidases) play critical roles in the maturation of Asn-linked glycoproteins in the endoplasmic reticulum (ER) and Golgi complex as well as influencing the timing and recognition for disposal of terminally unfolded proteins by ER-associated degradation. In an effort to define the structural basis for substrate recognition among Class 1 mannosidases, we have crystallized murine Golgi mannosidase IA (space group P212121), and the structure was solved to 1.5-A resolution by molecular replacement. The enzyme assumes an (αα)7 barrel structure with a Ca2+ ion coordinated at the base of the barrel similar to other Class 1 mannosidases. Critical residues within the barrel structure that coordinate the Ca2+ ion or presumably bind and catalyze the hydrolysis of the glycone are also highly conserved. A Man6GlcNAc2 oligosaccharide attached to Asn515 in the murine enzyme was found to extend into the active site of an adjoining protein unit in the crystal lattice in a presumed enzyme-product complex. In contrast to an analogous complex previously isolated for Saccharomyces cerevisiae ER mannosidase I, the oligosaccharide in the active site of the murine Golgi enzyme assumes a different conformation to present an alternate oligosaccharide branch into the active site pocket. A comparison of the observed Protein-Carbohydrate Interactions for the murine Golgi enzyme with the binding cleft topologies of the other family 47 glycosidases provides a framework for understanding the structural basis for substrate recognition among this class of enzymes.
