title: Proteolysis of HCF-1 by Ser/Thr glycosylation-incompetent O-GlcNAc transferase:UDP-GlcNAc complexes.
abstract: 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.
authors.affiliation: Center for Integrative Genomics, University of Lausanne, Lausanne 1015, Switzerland;
authors.forename: Vaibhav
authors.initials: V
authors.lastname: Kapuria
authors.affiliation: Molecular Modeling Group, SIB Swiss Institute of Bioinformatics, Lausanne 1015, Switzerland;
authors.forename: Ute F
authors.initials: UF
authors.lastname: Röhrig
authors.affiliation: Center for Integrative Genomics, University of Lausanne, Lausanne 1015, Switzerland;
authors.forename: Tanja
authors.initials: T
authors.lastname: Bhuiyan
authors.affiliation: MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom.
authors.forename: Vladimir S
authors.initials: VS
authors.lastname: Borodkin
authors.affiliation: MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom.
authors.forename: Daan M F
authors.initials: DM
authors.lastname: van Aalten
authors.affiliation: Molecular Modeling Group, SIB Swiss Institute of Bioinformatics, Lausanne 1015, Switzerland;
authors.forename: Vincent
authors.initials: V
authors.lastname: Zoete
authors.affiliation: Center for Integrative Genomics, University of Lausanne, Lausanne 1015, Switzerland;
authors.forename: Winship
authors.initials: W
authors.lastname: Herr
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D020134:Catalytic Domain; D003198:Computer Simulation; D019143:Evolution, Molecular; D051863:Host Cell Factor C1 / Q000378:metabolism*; D006801:Humans; D007448:Invertebrates / Q000201:enzymology; D008958:Models, Molecular; D009154:Mutation; D017351:N-Acetylglucosaminyltransferases / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D059748:Proteolysis
chemical_list: C497692:HCFC1 protein, human; D051863:Host Cell Factor C1; D017351:N-Acetylglucosaminyltransferases; C449880:O-GlcNAc transferase; C063057:UDP-N-acetylglucosamine-peptide beta-N-acetylglucosaminyltransferase
keywords: O-GlcNAcylation; post-translation modifications; proteolysis