Wolbachia-induced proteostasis remodeling in ovaries supports cytoplasmic incompatibility rescue in Drosophila.

The endosymbiont Wolbachia can modulate host reproduction to promote its own spread through host populations. Cytoplasmic incompatibility (CI) is a prevalent reproductive strategy induced by Wolbachia in insects, wherein embryos from infected males and uninfected females cannot develop normally; however, infected females rescue this embryonic lethality, thereby favoring its maternal transmission. The ovarian mechanisms that facilitate Wolbachia transmission and enable CI rescue remain largely unclear. Here, we integrated ovarian proteomics and ubiquitin-proteomics, and compared these datasets with published testis multi-omics data to characterize gonad-specific regulation by Wolbachia in Drosophila melanogaster. We identified 326 distinct proteins and 101 distinct ubiquitinated proteins in ovaries with and without wMel. Most of these proteins showed higher abundance or were detected only in Wolbachia-infected ovaries. Among these changes, many proteins were associated with processes related to translation and oogenesis. Wolbachia infection was associated with a significant decrease in proteasome activity in fly testes but a significant increase in ovaries. Comparative analysis further identified 57 proteins with opposite Wolbachia-associated abundance patterns between testes and ovaries, including the ER translocon subunit Sec61β. Overexpression of Sec61β in either Wolbachia-infected testes or uninfected ovaries rescued CI. These results suggest that Wolbachia infection induces widespread alterations in ovarian protein abundance through modulation of translation and ubiquitin-proteasome pathway (UPP)-mediated proteolysis. This finding provides new evidence for the host modification model of CI and for the preferential colonization of the ovary by Wolbachia to ensure its vertical transmission.