A chemical genetic method for monitoring genome-wide dynamics of O-GlcNAc turnover on chromatin-associated proteins.

O-linked N-acetylglucosamine (O-GlcNAc) is a necessary protein modification installed onto hundreds of nucleocytoplasmic proteins by O-GlcNAc transferase (OGT). Recently, we developed an antibody-free metabolic feeding approach that enables unbiased mapping of O-GlcNAcylated proteins in a genome-wide manner, providing insight into the regulation of genes by O-GlcNAcylated proteins within Drosophila. Here we apply this O-GlcNAc chemical mapping strategy to a time course (TC) feeding experiment within Drosophila larvae, generated the first ever TC ChIP-seq experiment performed on both a protein modification and within a living organism. TC metabolic labeling experiments were performed in wild-type and O-GlcNAc hydrolase (OGA) deficient Drosophila. Analysis of the resulting sequencing data revealed that a loss of OGA causes a global increase in the retention of O-GlcNAc modification on proteins bound to the genome, suggesting most nuclear proteins are sensitive to effects of O-GlcNAc cycling. Interestingly, some loci are more sensitive to the impacts of a loss of OGA compared to others. This study will present an improved understanding of the regulation of gene expression by O-GlcNAc while providing the broader community with experimental methods for time-resolved analysis of genome-wide binding by proteins. Overall design: Time course O-GlcNAc-seq and OGA ChIP-seq in wild type (WT) and OGA knockout (OGA-null) Drosophila larvae.