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Engineering the Ligand Specificity of the Human Galectin-1 by Incorporation of Tryptophan Analogues |
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| Authors: | Felix Tobola Dr Martin Lep?ík Dr Syeda Rehana Zia Dr Hakon Leffler Dr Ulf J Nilsson Dr Ola Blixt Dr Anne Imberty Dr Birgit Wiltschi |
| Affiliation: | 1. acib - Austrian Centre of Industrial Biotechnology, Petersgasse 14, 8010 Graz, Austria;2. Université Grenoble Alpes, CNRS, CERMAV, 38000 Grenoble, France;3. Department of Chemistry, University of Karachi, Karachi, Pakistan;4. Department of Laboratory Medicine, Section MIG, Lund University BMC-C1228b, Klinikgatan 28, 221 84 Lund, Sweden;5. Centre for Analysis and Synthesis, Department of Chemistry, Lund University, POB 124, Box 124, 221 00 Lund, Sweden;6. Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, 2800 Kgs. Lyngby, Denmark |
| Abstract: | Galectin-1 is a β-galactoside-binding lectin with manifold biological functions. A single tryptophan residue (W68) in its carbohydrate binding site plays a major role in ligand binding and is highly conserved among galectins. To fine tune galectin-1 specificity, we introduced several non-canonical tryptophan analogues at this position of human galectin-1 and analyzed the resulting variants using glycan microarrays. Two variants containing 7-azatryptophan and 7-fluorotryptophan showed a reduced affinity for 3’-sulfated oligosaccharides. Their interaction with different ligands was further analyzed by fluorescence polarization competition assay. Using molecular modeling we provide structural clues that the change in affinities comes from modulated interactions and solvation patterns. Thus, we show that the introduction of subtle atomic mutations in the ligand binding site of galectin-1 is an attractive approach for fine-tuning its interactions with different ligands. |
| Keywords: | lectins molecular dynamics non-canonical amino acids protein engineering synthetic glycobiology |