Impact of Germline Depletion of Bonus on Chromatin State in Drosophila Ovaries

Gene expression is controlled via complex regulatory mechanisms involving transcription factors, chromatin modifications, and chromatin regulatory factors. Histone modifications, such as H3K27me3, H3K9ac, and H3K27ac, play an important role in controlling chromatin accessibility and transcriptional output. In vertebrates, the Transcriptional Intermediary Factor 1 (TIF1) family of proteins play essential roles in transcription, cell differentiation, DNA repair, and mitosis. Our study focused on Bonus, the sole member of the TIF1 family in Drosophila, to investigate its role in organizing epigenetic modifications. Our findings demonstrated that depleting Bonus in ovaries leads to a mild reduction in the H3K27me3 level over transposon regions and alters the distribution of active H3K9ac marks on specific protein-coding genes. Additionally, through mass spectrometry analysis, we identified novel interacting partners of Bonus in ovaries, such as PolQ, providing a comprehensive understanding of the associated molecular pathways. Furthermore, our research revealed Bonus’s interactions with the Polycomb Repressive Complex 2 and its co-purification with select histone acetyltransferases, shedding light on the underlying mechanisms behind these changes in chromatin modifications.