The conserved threonine-rich region of the HCF-1PRO repeat activates promiscuous OGT:UDP-GlcNAc glycosylation and proteolysis activities.
J Biol Chem
; 293(46): 17754-17768, 2018 11 16.
Article
em En
| MEDLINE
| ID: mdl-30224358
ABSTRACT
O-Linked GlcNAc transferase (OGT) possesses dual glycosyltransferase-protease activities. OGT thereby stably glycosylates serines and threonines of numerous proteins and, via a transient glutamate glycosylation, cleaves a single known substrate-the so-called HCF-1PRO repeat of the transcriptional co-regulator host-cell factor 1 (HCF-1). Here, we probed the relationship between these distinct glycosylation and proteolytic activities. For proteolysis, the HCF-1PRO repeat possesses an important extended threonine-rich region that is tightly bound by the OGT tetratricopeptide-repeat (TPR) region. We report that linkage of this HCF-1PRO-repeat, threonine-rich region to heterologous substrate sequences also potentiates robust serine glycosylation with the otherwise poor Rp-αS-UDP-GlcNAc diastereomer phosphorothioate and UDP-5S-GlcNAc OGT co-substrates. Furthermore, it potentiated proteolysis of a non-HCF-1PRO-repeat cleavage sequence, provided it contained an appropriately positioned glutamate residue. Using serine- or glutamate-containing HCF-1PRO-repeat sequences, we show that proposed OGT-based or UDP-GlcNAc-based serine-acceptor residue activation mechanisms can be circumvented independently, but not when disrupted together. In contrast, disruption of both proposed activation mechanisms even in combination did not inhibit OGT-mediated proteolysis. These results reveal a multiplicity of OGT glycosylation strategies, some leading to proteolysis, which could be targets of alternative molecular regulatory strategies.
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MEDLINE
Assunto principal:
Endopeptidases
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N-Acetilglucosaminiltransferases
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Fator C1 de Célula Hospedeira
Limite:
Humans
Idioma:
En
Revista:
J Biol Chem
Ano de publicação:
2018
Tipo de documento:
Article
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