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Publication Abstract from PubMed

The structural features of MUC1-like glycopeptides bearing the Tn antigen (alpha-O-GalNAc-Ser/Thr) in complex with an anti MUC-1 antibody are reported at atomic resolution. For the alpha-O-GalNAc-Ser derivative, the glycosidic linkage adopts a high-energy conformation, barely populated in the free state. This unusual structure (also observed in an alpha-S-GalNAc-Cys mimic) is stabilized by hydrogen bonds between the peptidic fragment and the sugar. The selection of a particular peptide structure by the antibody is thus propagated to the carbohydrate through carbohydrate/peptide contacts, which force a change in the orientation of the sugar moiety. This seems to be unfeasible in the alpha-O-GalNAc-Thr glycopeptide owing to the more limited flexibility of the side chain imposed by the methyl group. Our data demonstrate the non-equivalence of Ser and Thr O-glycosylation points in molecular recognition processes. These features provide insight into the occurrence in nature of the APDTRP epitope for anti-MUC1 antibodies.

Deciphering the Non-Equivalence of Serine and Threonine O-Glycosylation Points: Implications for Molecular Recognition of the Tn Antigen by an anti-MUC1 Antibody.,Martinez-Saez N, Castro-Lopez J, Valero-Gonzalez J, Madariaga D, Companon I, Somovilla VJ, Salvado M, Asensio JL, Jimenez-Barbero J, Avenoza A, Busto JH, Bernardes GJ, Peregrina JM, Hurtado-Guerrero R, Corzana F Angew Chem Int Ed Engl. 2015 Jun 26. doi: 10.1002/anie.201502813. PMID:26118689^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.