DNA probe pulldown screening uncovers O-GlcNAcylation modulation of transcription factor DNA interactions

O-linked β-N-acetylglucosamine (O-GlcNAc), a critical post-translational modification predominantly found in the nucleus, plays a substantial role in regulating gene expression by modulating transcription factors (TFs) activity. However, quantitative analysis investigating the influence of O-GlcNAcylation on protein-DNA interactions at a proteome scale remains undone. Herein, a pulldown screening approach using a consensus TF response element (catTFRE) was employed to unravel the impact of fluctuating levels of O-GlcNAcylation on the DNA binding efficiency of endogenous TFs/co-factors. Utilizing quantitative proteomics, we identified a substantial enhancement in the binding capacity of 241 nuclear proteins (NPs) to DNA sequences due to elevated levels of O-GlcNAcylation, whereas a decrease in DNA binding was observed for 2 NPs concurrently. Intriguingly, the O-GlcNAcylation elevation significantly enhanced the binding of 146 TFs/co-factors to specific DNA sequences. We further established that the O-GlcNAcylation of several Forkhead family TFs, including FOXA1 and FOXC1, notably enhances their binding to specific DNA sequences in living cells. Our research presents an efficacious approach to assessing the impact of O-GlcNAcylation on the interactions between proteins and DNA. This significantly enhances our understanding of the role O-GlcNAcylation plays in the regulation of transcription.