title: Distinct OGT-Binding Sites Promote HCF-1 Cleavage.
abstract: Human HCF-1 (also referred to as HCFC-1) is a transcriptional co-regulator that undergoes a complex maturation process involving extensive O-GlcNAcylation and site-specific proteolysis. HCF-1 proteolysis results in two active, noncovalently associated HCF-1N and HCF-1C subunits that regulate distinct phases of the cell-division cycle. HCF-1 O-GlcNAcylation and site-specific proteolysis are both catalyzed by O-GlcNAc transferase (OGT), which thus displays an unusual dual enzymatic activity. OGT cleaves HCF-1 at six highly conserved 26 amino acid repeat sequences called HCF-1PRO repeats. Here we characterize the substrate requirements for OGT cleavage of HCF-1. We show that the HCF-1PRO-repeat cleavage signal possesses particular OGT-binding properties. The glutamate residue at the cleavage site that is intimately involved in the cleavage reaction specifically inhibits association with OGT and its bound cofactor UDP-GlcNAc. Further, we identify a novel OGT-binding sequence nearby the first HCF-1PRO-repeat cleavage signal that enhances cleavage. These results demonstrate that distinct OGT-binding sites in HCF-1 promote proteolysis, and provide novel insights into the mechanism of this unusual protease activity.
authors: Center for Integrative Genomics, University of Lausanne, Génopode, Lausanne, Switzerland.
authors: Tanja
authors: T
authors: Bhuiyan
authors: Protein Analysis Facility, Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Génopode, Lausanne, Switzerland.
authors: Patrice
authors: P
authors: Waridel
authors: Center for Integrative Genomics, University of Lausanne, Génopode, Lausanne, Switzerland.
authors: Vaibhav
authors: V
authors: Kapuria
authors: Molecular Modeling Group, Swiss Institute of Bioinformatics, Génopode, Lausanne, Switzerland.
authors: Vincent
authors: V
authors: Zoete
authors: Center for Integrative Genomics, University of Lausanne, Génopode, Lausanne, Switzerland.
authors: Winship
authors: W
authors: Herr
mesh_terms: D001665:Binding Sites; D048749:Cytokinesis / Q000235:genetics; D018698:Glutamic Acid / Q000378:metabolism; D006367:HeLa Cells; D051863:Host Cell Factor C1 / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D017351:N-Acetylglucosaminyltransferases / Q000235:genetics / Q000378:metabolism*; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism*; D059748:Proteolysis; D020449:Repetitive Sequences, Amino Acid / Q000235:genetics; D014158:Transcription, Genetic
chemical_list: C497692:HCFC1 protein, human; D051863:Host Cell Factor C1; D021122:Protein Subunits; D018698:Glutamic Acid; D017351:N-Acetylglucosaminyltransferases; C449880:O-GlcNAc transferase