School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan 430079, China.
Int J Mol Sci. 2022 Aug 21;23(16):9459. doi: 10.3390/ijms23169459.
The endosymbiotic Wolbachia bacteria frequently cause cytoplasmic incompatibility (CI) in their insect hosts, where Wolbachia-infected males cross with uninfected females, leading to no or fewer progenies, indicating a paternal modification by Wolbachia. Recent studies have identified a Wolbachia protein, CidB, containing a DUB (deubiquitylating enzyme) domain, which can be loaded into host sperm nuclei and involved in CI, though the DUB activity is not necessary for CI in Drosophila melanogaster. To investigate whether and how Wolbachia affect protein ubiquitination in testes of male hosts and are thus involved in male fertility, we compared the protein and ubiquitinated protein expressions in D. melanogaster testes with and without Wolbachia. A total of 643 differentially expressed proteins (DEPs) and 309 differentially expressed ubiquitinated proteins (DEUPs) were identified to have at least a 1.5-fold change with a p-value of <0.05. Many DEPs were enriched in metabolic pathway, ribosome, RNA transport, and post-translational protein modification pathways. Many DEUPs were involved in metabolism, ribosome, and proteasome pathways. Notably, 98.1% DEUPs were downregulated in the presence of Wolbachia. Four genes coding for DEUPs in ubiquitin proteasome pathways were knocked down, respectively, in Wolbachia-free fly testes. Among them, Rpn6 and Rpn7 knockdown caused male sterility, with no mature sperm in seminal vesicles. These results reveal deubiquitylating effects induced by Wolbachia infection, suggesting that Wolbachia can widely deubiquitinate proteins that have crucial functions in male fertility of their hosts, but are not involved in CI. Our data provide new insights into the regulatory mechanisms of endosymbiont/host interactions and male fertility.
共生的沃尔巴克氏体细菌经常在其昆虫宿主中引起细胞质不相容性（CI），即在沃尔巴克氏体感染的雄性与未感染的雌性交配时，导致后代数量减少甚至没有，表明沃尔巴克氏体对雄性进行了修饰。最近的研究发现，一种含有 DUB（去泛素化酶）结构域的沃尔巴克氏体蛋白 CidB 可以被加载到宿主精子核中，并参与 CI，尽管 DUB 活性对于黑腹果蝇的 CI 不是必需的。为了研究沃尔巴克氏体是否以及如何影响雄性宿主睾丸中的蛋白质泛素化，从而参与雄性生育能力，我们比较了有和没有沃尔巴克氏体的黑腹果蝇睾丸中的蛋白质和泛素化蛋白质的表达。共鉴定出 643 个差异表达蛋白（DEPs）和 309 个差异表达泛素化蛋白（DEUPs），它们的表达水平至少有 1.5 倍的变化，p 值<0.05。许多 DEPs 富集在代谢途径、核糖体、RNA 转运和翻译后蛋白质修饰途径中。许多 DEUPs 参与代谢、核糖体和蛋白酶体途径。值得注意的是，在有沃尔巴克氏体存在的情况下，98.1%的 DEUPs 下调。在没有沃尔巴克氏体的果蝇睾丸中分别敲低了 4 个编码泛素蛋白酶体途径中 DEUPs 的基因。其中，Rpn6 和 Rpn7 的敲低导致雄性不育，精囊内没有成熟精子。这些结果揭示了沃尔巴克氏体感染诱导的去泛素化作用，表明沃尔巴克氏体可以广泛地去泛素化那些对宿主生育能力至关重要的蛋白质，但不参与 CI。我们的数据为共生体/宿主相互作用和雄性生育能力的调控机制提供了新的见解。
