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Dynamic interplay between catalytic and lectin domains of GalNAc-transferases modulates protein O-glycosylation.

Nature communications (2015-05-06)
Erandi Lira-Navarrete, Matilde de Las Rivas, Ismael Compañón, María Carmen Pallarés, Yun Kong, Javier Iglesias-Fernández, Gonçalo J L Bernardes, Jesús M Peregrina, Carme Rovira, Pau Bernadó, Pierpaolo Bruscolini, Henrik Clausen, Anabel Lostao, Francisco Corzana, Ramon Hurtado-Guerrero
RÉSUMÉ

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.

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Uridine 5′-diphospho-N-acetylgalactosamine disodium salt, ≥97%