Identification of a secondary binding site in human macrophage galactose-type lectin by microarray studies: Implications for the molecular recognition of its ligands

Abstract

Shown is the 2D-rdf function derived from 200-ns MD simulations between carbonyl (CO) of the glycosylated Thr and the polar nitrogen N⑀ of the aromatic ring of His 259 (top), together with the water density (shown in red) calculated for the MGL-His 259 /MUC1-derived Tn-glycopeptide complex. No water density was detected in the case of MGL-Thr 259 /MUC1-derived Tn-glycopeptide complex. Fine specificity of the C-type lectin MGL

The Plasticity of the Carbohydrate Recognition Domain Dictates the Exquisite Mechanism of Binding of Human Macrophage Galactose‐Type Lectin

“…Hence, the variation of the frequency of hydrogen bond population involving H286 might explain the difference in Δ δ comb of 4 for GalNAc (Figure D and Figure C). Particularly, the importance of H286 in the recognition of GM2‐related compounds has been previously demonstrated, which is fully compatible with the data presented herein. The present data reinforce the conclusion that MGL‐CRD displays an extended binding pocket that is far from the QPD motif and where H286 is critical for the optimal recognition of GalNAc‐containing extended ligands.…”

“…Moreover, 2 and 4 are linear structures, whereas 1 and 3 show a branched fucose and a branched sialic acid unit, respectively. From the functional perspective, all the selected GalNAc‐containing fragments 1 – 4 are intrinsically associated with MGL tumor biology …”

“…Specifically,t he GalNAc moiety of bloodg roup Aa ntigen (1)a nd Forssman antigen (2) are a-substituted by Gal or GalNAc units, respectively.I nc ontrast, the GM2 (3)a nd asialoGM2 (4)a re substituted by a b-Gal moiety.M oreover, 2 and 4 are linear structures,w hereas 1 and 3 show ab ranched fucose and ab ranched sialica cid unit, respectively.F romt he functional perspective,a ll the selected GalNAc-containing fragments 1-4 are intrinsically associated with MGL tumor biology. [1,7,13,14] Analysis of the 1 H, 15 NHSQC NMR spectra of MGL-CRDi nt he presence of 1-4 MGL-CRDw as titrated with increasing concentrations of compounds 1-4 (see Experimental Section). FigureS6-S9 displays the 1 H, 15 NH SQC spectra of MGL-CRD and the corresponding Dd comb in the absence and presence of 1-4 at a1 :10 molar ratio of MGL-CRD/ligand.…”

“…[6] The molecular recognition of more complex GalNAc-containing structuresb yM GL has been extensively investigated by using glycan microarrays, surface plasmon resonance and cellularb inding assays,s howing high binding specificity to O-glycanT n-structures (aGalNAc-Ser/Thr), helminth glycans (fucosylateda nd non-fucosylated LacdiNAc structures), glycosphingolipid structures (GM2 and GD2), Forssman antigen,a nd blood group Aa ntigen. [1,7] In this context, by sensing Tn-structures present on self-glycoproteins (CD43/CD45) and on tumor-associated MUC1 glycoprotein, MGL induces immunosuppressive responsesi nm alignancy, characterized by increased IL-10, production and induction of regulatory Tcells, and the effector Tcell apoptosis. [8][9][10][11][12] Furthermore, the MGL ligands GM2/GD2 and Forssman antigen are known tumor-associated antigens that are present in several tumors, [1,7,13] which may correlate with the role of MGL in malignancy.…”

“…[1,7] In this context, by sensing Tn-structures present on self-glycoproteins (CD43/CD45) and on tumor-associated MUC1 glycoprotein, MGL induces immunosuppressive responsesi nm alignancy, characterized by increased IL-10, production and induction of regulatory Tcells, and the effector Tcell apoptosis. [8][9][10][11][12] Furthermore, the MGL ligands GM2/GD2 and Forssman antigen are known tumor-associated antigens that are present in several tumors, [1,7,13] which may correlate with the role of MGL in malignancy. Additionally,i narat model, MGL binding to the blood group Aa ntigen correlates with increased apoptosis resistancea nd the ability of cancerc ellst oe scape immune surveillance, which may also be ascribed to the immunosuppressive properties of MGL.…”