Proteolysis of HCF-1 by Ser/Thr glycosylation-incompetent O-GlcNAc transferase:UDP-GlcNAc complexes

In complex with the cosubstrate UDP-N-acetylglucosamine (UDP-GlcNAc),O-linked-GlcNAc transferase (OGT) catalyzes Ser/ThrO-GlcNAcylation of many cellular proteins and proteolysis of the transcriptional coregulator HCF-1. Such a dual glycosyltransferase-protease activity, which occurs in the same acti...

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Bibliographic Details
Published in:Genes & development 2016-04, Vol.30 (8), p.960-972
Main Authors: Kapuria, Vaibhav, Röhrig, Ute F, Bhuiyan, Tanja, Borodkin, Vladimir S, van Aalten, Daan M F, Zoete, Vincent, Herr, Winship
Format: Article
Language:English
Subjects:
Amino Acid Motifs
Animals
Catalytic Domain
Computer Simulation
Evolution, Molecular
Host Cell Factor C1 - metabolism
Humans
Invertebrates - enzymology
Models, Molecular
Mutation
N-Acetylglucosaminyltransferases - metabolism
Protein Processing, Post-Translational
Protein Structure, Tertiary
Proteolysis
Research Paper
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Summary:In complex with the cosubstrate UDP-N-acetylglucosamine (UDP-GlcNAc),O-linked-GlcNAc transferase (OGT) catalyzes Ser/ThrO-GlcNAcylation of many cellular proteins and proteolysis of the transcriptional coregulator HCF-1. Such a dual glycosyltransferase-protease activity, which occurs in the same active site, is unprecedented and integrates both reversible and irreversible forms of protein post-translational modification within one enzyme. Although occurring within the same active site, we show here that glycosylation and proteolysis occur through separable mechanisms. OGT consists of tetratricopeptide repeat (TPR) and catalytic domains, which, together with UDP-GlcNAc, are required for both glycosylation and proteolysis. Nevertheless, a specific TPR domain contact with the HCF-1 substrate is critical for proteolysis but not Ser/Thr glycosylation. In contrast, key catalytic domain residues and even a UDP-GlcNAc oxygen important for Ser/Thr glycosylation are irrelevant for proteolysis. Thus, from a dual glycosyltransferase-protease, essentially single-activity enzymes can be engineered both in vitro and in vivo. Curiously, whereas OGT-mediated HCF-1 proteolysis is limited to vertebrate species, invertebrate OGTs can cleave human HCF-1. We present a model for the evolution of HCF-1 proteolysis by OGT.
ISSN:0890-9369
1549-5477
DOI:10.1101/gad.275925.115