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Crystal structure of Calsepa lectin in complex with biantennary N-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 PubMedMannose-binding type Jacalin-related lectins (mJRLs) bind to branched N-glycans via conserved sugar binding sites. Despite significant 3D structural similarities, each mJRL is known to have a unique binding preference towards various N-glycans. However, the molecular basis of varying binding preference is substantially unknown. Here we report a detailed comparison of N-glycan binding preference for two mJRLs, Orysata and Calsepa using frontal affinity chromatography (FAC), X-ray and molecular modeling. The FAC analysis using a panel of N-glycans shows difference in N-glycan binding preference between the lectins. Orysata shows broader specificity toward most high-mannose-type glycans as well as biantennary complex-type glycans bearing an extension on the Manalpha1-6 branch. Whereas, Calsepa shows narrow specificity to complex-type glycans with bisecting GlcNAc. The X-ray crystallographic structure reveals that two Orysata lectins bind to one biantennary N-glycan (2:1 binding) where one lectin binds to mannose of the alpha1-3 branch, while the other interacts with an N-acetylglucosamine of the alpha1-6 branch. In contrast, Calsepa shows 1:1 binding where alpha1-3 branch and core chitobiose region N-glycan interacts with lectin, while alpha1-6 branch is flipped back to the chitobiose core. Molecular dynamics study of Orysata bound to N-glycans substantiate possibility of two binding modes for each N-glycan. Binding free energies calculated separately for alpha1-3 and alpha1-6 branches of each N-glycan suggest both branches can bind to Orysata. Overall these results suggest that each branch of N-glycan has a distinct role in binding mJRLs and the non-binding branch can contribute significantly to the binding affinity and hence to the specificity. Distinct roles for each N-glycan branch interacting with mannose-binding type Jacalin-related lectins Orysata and Calsepa.,Nagae M, Mishra SK, Hanashima S, Tateno H, Yamaguchi Y Glycobiology. 2017 Sep 7. doi: 10.1093/glycob/cwx081. PMID:28973127[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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