Differential splicing of the lectin domain of an O-glycosyltransferase modulates both peptide and glycopeptide preferences
| Autor: | Carolyn May, Thomas A. Gerken, Zulfeqhar Syed, Leslie Revoredo, Earnest James Paul Daniel, Nadine L. Samara, Kelly G. Ten Hagen, Suena Ji, Lawrence A. Tabak |
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| Rok vydání: | 2020 |
| Předmět: |
0301 basic medicine
chemistry.chemical_classification 030102 biochemistry & molecular biology biology In silico Alternative splicing Lectin Peptide Cell Biology Biochemistry Glycopeptide carbohydrates (lipids) 03 medical and health sciences 030104 developmental biology Enzyme chemistry Glycosyltransferase RNA splicing biology.protein Molecular Biology |
| Zdroj: | Journal of Biological Chemistry. 295:12525-12536 |
| ISSN: | 0021-9258 |
| Popis: | Mucin-type O-glycosylation is an essential post-translational modification required for protein secretion, extracellular matrix formation, and organ growth. O-Glycosylation is initiated by a large family of enzymes (GALNTs in mammals and PGANTs in Drosophila) that catalyze the addition of GalNAc onto the hydroxyl groups of serines or threonines in protein substrates. These enzymes contain two functional domains: a catalytic domain and a C-terminal ricin-like lectin domain comprised of three potential GalNAc recognition repeats termed α, β, and γ. The catalytic domain is responsible for binding donor and acceptor substrates and catalyzing transfer of GalNAc, whereas the lectin domain recognizes more distant extant GalNAc on previously glycosylated substrates. We previously demonstrated a novel role for the α repeat of lectin domain in influencing charged peptide preferences. Here, we further interrogate how the differentially spliced α repeat of the PGANT9A and PGANT9B O-glycosyltransferases confers distinct preferences for a variety of endogenous substrates. Through biochemical analyses and in silico modeling using preferred substrates, we find that a combination of charged residues within the α repeat and charged residues in the flexible gating loop of the catalytic domain distinctively influence the peptide substrate preferences of each splice variant. Moreover, PGANT9A and PGANT9B also display unique glycopeptide preferences. These data illustrate how changes within the noncatalytic lectin domain can alter the recognition of both peptide and glycopeptide substrates. Overall, our results elucidate a novel mechanism for modulating substrate preferences of O-glycosyltransferases via alternative splicing within specific subregions of functional domains. |
| Databáze: | OpenAIRE |
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