Open AccessCalorimetric Analysis of the Interplay between Synthetic Tn Antigen-Presenting MUC1 Glycopeptides and Human Macrophage Galactose-Type Lectin
Author(s) -
Donella Beckwith,
Forrest G FitzGerald,
Maria C. Rodriguez Benavente,
Elizabeth R Mercer,
AnnaKristin Ludwig,
Malwina Michalak,
Herbert Kaltner,
Jürgen Kopitz,
HansJoachim Gabius,
Mare Čudić
Publication year - 2021
Publication title -
biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.43
H-Index - 253
eISSN - 1520-4995
pISSN - 0006-2960
DOI - 10.1021/acs.biochem.0c00942
Subject(s) - isothermal titration calorimetry , lectin , glycan , chemistry , glycosylation , glycoproteomics , biochemistry , threonine , glycopeptide , c type lectin , glycomics , peptide , microbiology and biotechnology , glycoprotein , serine , biology , enzyme , antibiotics
Human macrophage galactose-type lectin (hMGL, HML, CD301, CLEC10A), a C-type lectin expressed by dendritic cells and macrophages, is a receptor for N -acetylgalactosamine α-linked to serine/threonine residues (Tn antigen, CD175) and its α2,6-sialylated derivative (sTn, CD175s). Because these two epitopes are among malignant cell glycan displays, particularly when presented by mucin-1 (MUC1), assessing the influence of the site and frequency of glycosylation on lectin recognition will identify determinants governing this interplay. Thus, chemical synthesis of the tandem-repeat O -glycan acceptor region of MUC1 and site-specific threonine glycosylation in all permutations were carried out. Isothermal titration calorimetry (ITC) analysis of the binding of hMGL to this library of MUC1 glycopeptides revealed an enthalpy-driven process and an affinity enhancement of an order of magnitude with an increasing glycan count from 6-8 μM for monoglycosylated peptides to 0.6 μM for triglycosylated peptide. ITC measurements performed in D 2 O permitted further exploration of the solvation dynamics during binding. A shift in enthalpy-entropy compensation and contact position-specific effects with the likely involvement of the peptide surroundings were detected. KinITC analysis revealed a prolonged lifetime of the lectin-glycan complex with increasing glycan valency and with a change in the solvent to D 2 O.