6 results on '"Russwurm R"'
Search Results
2. Activity-structure correlations in divergent lectin evolution: fine specificity of chicken galectin CG-14 and computational analysis of flexible ligand docking for CG-14 and the closely related CG-16.
- Author
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Wu AM, Singh T, Liu JH, Krzeminski M, Russwurm R, Siebert HC, Bonvin AM, André S, and Gabius HJ
- Subjects
- Amino Acid Sequence, Animals, Antigens, Tumor-Associated, Carbohydrate metabolism, Chickens, Computational Biology, Galectins antagonists & inhibitors, Gene Duplication, Humans, Lectins antagonists & inhibitors, Lectins metabolism, Ligands, Models, Biological, Molecular Sequence Data, Oligosaccharides pharmacology, Protein Conformation, Structure-Activity Relationship, Evolution, Molecular, Galactosides metabolism, Galectins chemistry, Galectins metabolism, Lectins chemistry
- Abstract
Gene duplication and sequence divergence are driving forces toward establishing protein families. To examine how sequence changes affect carbohydrate specificity, the two closely related proto-type chicken galectins CG-14 and CG-16 were selected as models. Binding properties were analyzed using a highly sensitive solid-phase assay. We tested 56 free saccharides and 34 well-defined glycoproteins. The two galectins share preference for the II (Galbeta1-4GlcNAc) versus I (Galbeta1-3GlcNAc) version of beta-galactosides. A pronounced difference is found owing to the reactivity of CG-14 with histo-blood group ABH active oligosaccharides and A/B active glycoproteins. These experimental results prompted to determine activity-structure correlations by modeling. Computational analysis included consideration of the flexibility of binding partners and the presence of water molecules. It provided a comparative description of complete carbohydrate recognition domains, which had so far not been characterized in animal galectins. The structural models assigned II, I selectivity to a region downstream of the central Trp moiety. Docking revealed that the tetrasaccharides can be accommodated in their free-state low-energy conformations. CG-14's preference for A versus B epitopes could be attributed to a contact between His124 and the N-acetyl group of GalNAc. Regarding intergalectin comparison, the Ala53/Cys51 exchange affects the interaction potential of His54/His52. Close inspection of simulated dynamic interplay revealed reorientation of His124 at the site of the His124/Glu123 substitution, with potential impact on ligand dissociation. In summary, this study identifies activity differences and provides information on their relation to structural divergence, epitomizing the value of this combined approach beyond galectins.
- Published
- 2007
- Full Text
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3. Unique sequence and expression profiles of rat galectins-5 and -9 as a result of species-specific gene divergence.
- Author
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Lensch M, Lohr M, Russwurm R, Vidal M, Kaltner H, André S, and Gabius HJ
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- Amino Acid Sequence, Animals, Base Sequence, Chromosome Mapping, Galectins analysis, Gene Expression Profiling, Immunohistochemistry, Mice, Molecular Sequence Data, Promoter Regions, Genetic, RNA, Messenger analysis, RNA, Messenger metabolism, Rats, Tissue Distribution, Erythropoiesis genetics, Galectins genetics, Gene Expression Regulation, Genetic Variation
- Abstract
Presence of species-specific gene divergence in a protein family prompts to thoroughly study structural aspects and expression profiles of the products. We herein focus on two members of an adhesion/growth-regulatory group of endogenous lectins, i.e. galectins-5 and -9. After first ascertaining species specificity of occurrence of galectin-5, constituted by a short section of rat galectin-9's N-terminal part and its C-terminal carbohydrate recognition domain, by database mining, we next detected and defined sequence differences in the proximal promoter region between the two genes. The ensuing hypothesis for distinct expression profiles was tested first by RT-PCR and then by immunohistochemistry. For the latter purpose, we employed antibodies rigorously controlled for absence of cross-reactivity including assays with various other galectins and, if necessary, refined by chromatographic removal of bi- or oligospecific activities. Indeed, the galectins have non-identical expression profiles, qualitative differences, e.g. seen for galectin-5-positive bone marrow and erythrocytes or for hitherto unknown expression in cells of the theca folliculi and galectin-9-positive skin epidermis and esophageal epithelium. Lack of hepatocyte or renal cortex staining separates these two expression profiles in rat from localization of galectin-9 in mouse. Interspecies extrapolation in a case of a galectin involved in unique gene divergence may thus not be valid. The presented results on galectin-5 relative to galectin-9 intimate distinct functions especially in erythropoiesis and imply currently unknown mechanisms to compensate its absence from the galectin network in other mammals.
- Published
- 2006
- Full Text
- View/download PDF
4. Determination of structural and functional overlap/divergence of five proto-type galectins by analysis of the growth-regulatory interaction with ganglioside GM1 in silico and in vitro on human neuroblastoma cells.
- Author
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André S, Kaltner H, Lensch M, Russwurm R, Siebert HC, Fallsehr C, Tajkhorshid E, Heck AJ, von Knebel Doeberitz M, Gabius HJ, and Kopitz J
- Subjects
- Amino Acid Sequence, Animals, Chickens, Galectin 1 metabolism, Galectin 2 metabolism, Galectin 3 metabolism, Galectin 4 metabolism, Humans, Ligands, Models, Molecular, Molecular Sequence Data, Protein Structure, Quaternary, Rats, Reverse Transcriptase Polymerase Chain Reaction, Sequence Analysis, DNA, Tumor Cells, Cultured, G(M1) Ganglioside metabolism, Galectins metabolism, Neuroblastoma metabolism
- Abstract
The growth-regulatory interplay between ganglioside GM1 on human SK-N-MC neuroblastoma cells and an endogenous lectin provides a telling example for glycan (polysaccharide) functionality. Galectin-1 is the essential link between the sugar signal and the intracellular response. The emerging intrafamily complexity of galectins raises the question on defining extent of their structural and functional overlap/divergence. We address this problem for proto-type galectins in this system: ganglioside GM1 as ligand, neuroblastoma cells as target. Using the way human galectin-1 interacts with this complex natural ligand as template, we first defined equivalent positioning for distinct substitutions in the other tested proto-type galectins, e.g., Lys63 vs. Leu60/Gln72 in galectins-2 and -5. As predicted from our in silico work, the tested proto-type galectins have affinity for the pentasaccharide of ganglioside GM1. In contrast to solid-phase assays, cell surface presentation of the ganglioside did not support binding of galectin-5, revealing the first level of regulation. Next, a monomeric proto-type galectin (CG-14) can impair galectin-1-dependent negative growth control by competitively blocking access to the shared ligand without acting as effector. Thus, the quaternary structure of proto-type galectins is an efficient means to give rise to functional divergence. The identification of this second level of regulation is relevant for diagnostic monitoring. It might be exploited therapeutically by producing galectin variants tailored to interfere with galectin activities associated with the malignant phenotype. Moreover, the given strategy for comparative computational analysis of extended binding sites has implications for the rational design of galectin-type-specific ligands.
- Published
- 2005
- Full Text
- View/download PDF
5. Identification of peptide ligands for malignancy- and growth-regulating galectins using random phage-display and designed combinatorial peptide libraries.
- Author
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André S, Arnusch CJ, Kuwabara I, Russwurm R, Kaltner H, Gabius HJ, and Pieters RJ
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- Animals, Combinatorial Chemistry Techniques, Humans, Ligands, Oligopeptides chemical synthesis, Oligopeptides chemistry, Protein Binding, Galectins chemistry, Peptide Library
- Abstract
Members of the galectin family of endogenous lectins are involved in tumor growth regulation and in establishing characteristics of the malignant phenotype via protein-carbohydrate and protein-protein interactions. To identify peptide ligands with the potential to modulate these tumor-relevant interactions beneficially, complementary screening methods were employed, that is, both phage-display and a combinatorial pentapeptide library with the key YXY tripeptide core. Three representative prototype galectins were selected. The search for high-affinity ligands among phage-displayed random heptamers yielded enrichment after five selection cycles of the nonglycomimetic CQSPSARSC peptide in the case of the chicken homologue of galectin-1 but not the human protein, an indication for specificity. The most active glycomimetic from the combinatorial library of 5832 pentamers was WYKYW. Identification of peptide ligands for galectins with and without glycomimetic properties is thus possible. Our study documents the potential to combine the two library-based approaches for structural optimization of lead peptides.
- Published
- 2005
- Full Text
- View/download PDF
6. Hippocampal neurons and recombinant galectins as tools for systematic carbohydrate structure-function studies in neuronal differentiation.
- Author
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Kopitz J, Russwurm R, Kaltner H, André S, Dotti CG, Gabius HJ, and Abad-Rodríguez J
- Subjects
- Animals, Axons drug effects, Axons physiology, Cell Differentiation drug effects, Cells, Cultured, Chick Embryo, Fluorescein-5-isothiocyanate, Fluorescent Antibody Technique, Fluorescent Dyes, Hippocampus cytology, Hippocampus drug effects, Lactose metabolism, Membranes drug effects, Membranes metabolism, Nerve Regeneration drug effects, Nerve Regeneration physiology, Nerve Tissue Proteins chemistry, Nerve Tissue Proteins pharmacology, Neurites drug effects, Neurites physiology, Neurons drug effects, Rats, Recombinant Proteins pharmacology, Reverse Transcriptase Polymerase Chain Reaction, Structure-Activity Relationship, Carbohydrates chemistry, Carbohydrates physiology, Galectins pharmacology, Hippocampus physiology, Neurons physiology
- Abstract
Membrane glycoconjugates play a central role in neuronal interactions and regulation. To define the precise links between membrane polysaccharides and neuronal functions, two main requirements must be fulfilled: (1) the availability of molecular tools able to finely discriminate among carbohydrate structures and (2) the use of an experimental system suitable for systematic and quantitative studies of particular neuronal processes. In this work, we used two chicken proto-type galectins, i.e., monomeric CG-14 and dimeric CG-16, with very similar carbohydrate affinities, and rat hippocampal neurons in culture to quantitatively measure the involvement of carbohydrate-protein interaction in axonal growth and directionality, neurite sprouting and axon regenerative capacity after section. CG-16 potently stimulated axonal growth and guidance. Neurite sprouting was enhanced by immobilized CG-16 and, notably, reduced by lectin in solution. Overall, cross-linking CG-16 invariably excelled CG-14 in these functional assays, although none of them were able to improve axon regenerative capacity when compared to mammalian galectin-1. Our results demonstrate the potential of the experimental set-up to perform a systematic study of galectin functionality in neuronal differentiation. In view of the concept of the sugar code, the presented results indicate that biological effects triggered by glycan binding engaging an endogenous lectin can be modulated by carbohydrate affinity and/or by other factors like differential cross-linking capacity.
- Published
- 2004
- Full Text
- View/download PDF
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