5av7
Crystal structure of Calsepa lectin in complex with bisected glycan
Structural highlights
FunctionLECC_CALSE Mannose-binding lectin (PubMed:9111143, PubMed:18266762, PubMed:14561768, PubMed:26971576, PubMed:28973127). Preferentially binds mannose at concentrations ranging between 5 and 25 mM, but binds also glucose. Has a marked preference for methylated sugar derivatives, such as alpha-MeMan and alpha-MeGlc, at concentration down to 5 mM (PubMed:14561768). Binds to N-glycans, but not to glycolipid-type or other type of glycans (PubMed:28973127). Binds N-linked high-mannose-type glycans (PubMed:18266762, PubMed:28973127). Has a preference for smaller (Man(2)-Man(6)) high-mannose-type glycans to larger (Man(7)-Man(9)) ones. Recognizes both alpha1-6 extended and alpha1-3 extended monoantennary glycans. The addition of alpha1-2Man to the Man-alpha1-3Man-beta branch results in a significant loss of affinity, but beta1-2GlcNAc has some affinity. Has less affinity for biantennary glycans (PubMed:18266762). However, affinity is significant for the biantennary complex-type N-glycans with bisecting GlcNAc (PubMed:18266762, PubMed:26971576, PubMed:28973127). No affinity is observed for tri- and tetra-antennary glycans (PubMed:18266762). Binds bisected glycans of the mouse brain. Selectively binds to bisecting N-glycans which are in back-fold conformation, and does not favor a glycan with an extend conformation (PubMed:26971576). Has hemagglutinating activity against rabbit erythrocytes at 0.3 ug/ml and against trypsin-treated human erythrocytes at 5 ug/ml. Has mitogenic activity in murine cells (PubMed:9111143).[1] [2] [3] [4] [5] Publication Abstract from PubMedGlycans normally exist as a dynamic equilibrium of several conformations. A fundamental question concerns how such molecules bind lectins despite disadvantageous entropic loss upon binding. Bisected glycan, a glycan possessing bisecting N-acetylglucosamine (GlcNAc), is potentially a good model for investigating conformational dynamics and glycan-lectin interactions, owing to the unique ability of this sugar residue to alter conformer populations and thus modulate the biological activities. Here we analyzed bisected glycan in complex with two unrelated lectins, Calsepa and PHA-E. The crystal structures of the two complexes show a conspicuous flipped back glycan structure (designated 'back-fold' conformation), and solution NMR analysis also provides evidence of 'back-fold' glycan structure. Indeed, statistical conformational analysis of available bisected and non-bisected glycan structures suggests that bisecting GlcNAc restricts the conformations of branched structures. Restriction of glycan flexibility by certain sugar residues may be more common than previously thought and impinges on the mechanism of glycoform-dependent biological functions. Atomic visualization of a flipped-back conformation of bisected glycans bound to specific lectins.,Nagae M, Kanagawa M, Morita-Matsumoto K, Hanashima S, Kizuka Y, Taniguchi N, Yamaguchi Y Sci Rep. 2016 Mar 14;6:22973. doi: 10.1038/srep22973. PMID:26971576[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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