PMID: 29208955

Authors:

Rivas ML, Lira-Navarrete E, Daniel EJP, Companon I, Coelho H, Diniz A, Jimenez-Barbero J, Peregrina JM, Clausen H, Corzana F, Marcelo F, Jimenez-Oses G, Gerken TA, Hurtado-Guerrero R

Title:

The interdomain flexible linker of the polypeptide GalNAc transferases dictates their long-range glycosylation preferences.

Journal:

Nat Commun. 2017 Dec 5;8(1):1959. doi: 10.1038/s41467-017-02006-0.

Abstract:

The polypeptide GalNAc-transferases (GalNAc-Ts), that initiate mucin-type O-glycosylation, consist of a catalytic and a lectin domain connected by a flexible linker. In addition to recognizing polypeptide sequence, the GalNAc-Ts exhibit unique long-range N- and/or C-terminal prior glycosylation (GalNAc-O-Ser/Thr) preferences modulated by the lectin domain. Here we report studies on GalNAc-T4 that reveal the origins of its unique N-terminal long-range glycopeptide specificity, which is the opposite of GalNAc-T2. The GalNAc-T4 structure bound to a monoglycopeptide shows that the GalNAc-binding site of its lectin domain is rotated relative to the homologous GalNAc-T2 structure, explaining their different long-range preferences. Kinetics and molecular dynamics simulations on several GalNAc-T2 flexible linker constructs show altered remote prior glycosylation preferences, confirming that the flexible linker dictates the rotation of the lectin domain, thus modulating the GalNAc-Ts' long-range preferences. This work for the first time provides the structural basis for the different remote prior glycosylation preferences of the GalNAc-Ts.