Motif-dependent binding on the intervening domain regulates O-GlcNAc transferase

The modification of intracellular proteins with O-linked & beta;-N-acetylglucosamine (O-GlcNAc) moieties is a highly dynamic process that spatiotemporally regulates nearly every important cellular program. Despite its significance, little is known about the substrate recognition and regulation modes of O-GlcNAc transferase (OGT), the primary enzyme responsible for O-GlcNAc addition. In this study, we identified the intervening domain (Int-D), a poorly understood protein fold found only in metazoan OGTs, as a specific regulator of OGT protein-protein interactions and substrate modification. Using proteomic peptide phage display (ProP-PD) coupled with structural, biochemical and cellular characterizations, we discovered a strongly enriched peptide motif, employed by the Int-D to facilitate specific O-GlcNAcylation. We further show that disruption of Int-D binding dysregulates important cellular programs, including response to nutrient deprivation and glucose metabolism. These findings illustrate a mode of OGT substrate recognition and offer key insights into the biological roles of this unique domain. Peptide phage display reveals a non-catalytic binding site on the intervening domain of O-GlcNAc transferase. Its roles in substrate recognition, posttranslational modification (PTM) crosstalk and nutrient response provide insight into the function of this cryptic domain.

Automated summary

Peptide phage display technique identifies the role of the intervening domain (Int-D) of O-GlcNAc transferase (OGT) in regulating protein-protein interactions and substrate modification. The study reveals the mode of OGT substrate recognition and provides insights into the biological function of the Int-D.