Resumen: Protein O-glycosylation is controlled by polypeptide GalNAc-transferases (GalNAc-Ts) that uniquely feature both a catalytic and lectin domain. The underlying molecular basis of how the lectin domains of GalNAc-Ts contribute to glycopeptide specificity and catalysis remains unclear. Here we present the first crystal structures of complexes of GalNAc-T2 with glycopeptides that together with enhanced sampling molecular dynamics simulations demonstrate a cooperative mechanism by which the lectin domain enables free acceptor sites binding of glycopeptides into the catalytic domain. Atomic force microscopy and small-angle X-ray scattering experiments further reveal a dynamic conformational landscape of GalNAc-T2 and a prominent role of compact structures that are both required for efficient catalysis. Our model indicates that the activity profile of GalNAc-T2 is dictated by conformational heterogeneity and relies on a flexible linker located between the catalytic and the lectin domains. Our results also shed light on how GalNAc-Ts generate dense decoration of proteins with O-glycans. Idioma: Inglés DOI: 10.1038/ncomms7937 Año: 2015 Publicado en: NATURE COMMUNICATIONS 6 (2015), 6937 [10 pp] ISSN: 2041-1723 Factor impacto JCR: 11.329 (2015) Categ. JCR: MULTIDISCIPLINARY SCIENCES rank: 3 / 62 = 0.048 (2015) - Q1 - T1 Factor impacto SCIMAGO: 6.287 - Biochemistry, Genetics and Molecular Biology (miscellaneous) (Q1) - Physics and Astronomy (miscellaneous) (Q1) - Chemistry (miscellaneous) (Q1)