title: Lectin domains of polypeptide GalNAc transferases exhibit glycopeptide binding specificity.
abstract: UDP-GalNAc:polypeptide α-N-acetylgalactosaminyltransferases (GalNAc-Ts) constitute a family of up to 20 transferases that initiate mucin-type O-glycosylation. The transferases are structurally composed of catalytic and lectin domains. Two modes have been identified for the selection of glycosylation sites by GalNAc-Ts: confined sequence recognition by the catalytic domain alone, and concerted recognition of acceptor sites and adjacent GalNAc-glycosylated sites by the catalytic and lectin domains, respectively. Thus far, only the catalytic domain has been shown to have peptide sequence specificity, whereas the primary function of the lectin domain is to increase affinity to previously glycosylated substrates. Whether the lectin domain also has peptide sequence selectivity has remained unclear. Using a glycopeptide array with a library of synthetic and recombinant glycopeptides based on sequences of mucins MUC1, MUC2, MUC4, MUC5AC, MUC6, and MUC7 as well as a random glycopeptide bead library, we examined the binding properties of four different lectin domains. The lectin domains of GalNAc-T1, -T2, -T3, and -T4 bound different subsets of small glycopeptides. These results indicate an additional level of complexity in the initiation step of O-glycosylation by GalNAc-Ts.
authors.affiliation: Department of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen, USA.
authors.forename: Johannes W
authors.initials: JW
authors.lastname: Pedersen
authors.forename: Eric P
authors.initials: EP
authors.lastname: Bennett
authors.forename: Katrine T-B G
authors.initials: KT
authors.lastname: Schjoldager
authors.forename: Morten
authors.initials: M
authors.lastname: Meldal
authors.forename: Andreas P
authors.initials: AP
authors.lastname: Holmér
authors.forename: Ola
authors.initials: O
authors.lastname: Blixt
authors.forename: Emiliano
authors.initials: E
authors.lastname: Cló
authors.forename: Steven B
authors.initials: SB
authors.lastname: Levery
authors.forename: Henrik
authors.initials: H
authors.lastname: Clausen
authors.forename: Hans H
authors.initials: HH
authors.lastname: Wandall
mesh_terms: D006020:Glycopeptides / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006031:Glycosylation; D006801:Humans; D037102:Lectins; D009077:Mucins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017350:N-Acetylgalactosaminyltransferases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D013379:Substrate Specificity / Q000502:physiology; D000097763:Polypeptide N-acetylgalactosaminyltransferase
chemical_list: D006020:Glycopeptides; D037102:Lectins; D009077:Mucins; D017350:N-Acetylgalactosaminyltransferases; D000097763:Polypeptide N-acetylgalactosaminyltransferase