Olfactory learning in Drosophila requires O-GlcNAcylation of mushroom body ribosomal subunits

O-GlcNAcylation is a dynamic post-translational modification that diversifies the proteome. Its dysregulation is associated with neurological disorders that impair cognitive function, and yet identification of phenotype-relevant candidate substrates in a brain-region specific manner remains unfeasible. By combining an O-GlcNAc binding activity derived from Clostridium perfringens OGA ( Cp OGA) with TurboID proximity labeling in Drosophila , we developed an O-GlcNAcylation profiling tool that translates O-GlcNAc modification into biotin conjugation for tissue-specific candidate substrates enrichment. We mapped the O-GlcNAc interactome in major brain regions of Drosophila and found that components of the translational machinery, including many ribosomal subunits, were abundantly O-GlcNAcylated in the mushroom body, the computational center of the Drosophila brain. Hypo-O-GlcNAcylation induced by ectopic expression of active Cp OGA in the mushroom body decreased local ribosomal activity, leading to olfactory learning deficits that could be rescued by increasing ribosome biogenesis. Our study reveals that O-GlcNAcylation contributes to the links between protein synthesis and cognitive function in the brain learning center, and provides a useful tool for future dissection of tissue-specific functions of O-GlcNAcylation in Drosophila . ### Competing Interest Statement The authors have declared no competing interest.