Structural highlights
FunctionPublication Abstract from PubMedPathogenic micro-organisms utilize protein receptors (lectins) in adhesion to host tissues, a process that in some cases relies on the interaction between lectins and human glycoconjugates. Oligosaccharide epitopes are recognized through their three-dimensional structure and their flexibility is a key issue in specificity. In this paper, we analysed by X-ray crystallography the structures of the LecB lectin from two strains of Pseudomonas aeruginosa in complex with Lewis x oligosaccharide present on cell surfaces of human tissues. An unusual conformation of the glycan was observed in all binding sites with a non-canonical syn orientation of the N-acetyl group of N-acetyl-glucosamine. A PDB-wide search revealed that such an orientation occurs only in 4% of protein/carbohydrate complexes. Theoretical chemistry calculations showed that the observed conformation is unstable in solution but stabilised by the lectin. A reliable description of LecB/Lewis x complex by force field-based methods had proven especially challenging due to the special feature of the binding site, two closely apposed Ca(2+) ions which induce strong charge delocalisation. By comparing various force-field parametrisations, we propose a general strategy which will be useful in near future for designing carbohydrate-based ligands (glycodrugs) against other calcium-dependent protein receptors. Induction of rare conformation of oligosaccharide by binding to calcium-dependent bacterial lectin: X-ray crystallography and modelling study.,Lepsik M, Sommer R, Kuhaudomlarp S, Lelimousin M, Paci E, Varrot A, Titz A, Imberty A Eur J Med Chem. 2019 May 18;177:212-220. doi: 10.1016/j.ejmech.2019.05.049. PMID:31146126[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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