Starr Diana J, Cline Thomas W
Department of Molecular and Cell Biology, 401 Barker Hall, University of California, Berkeley, California 94720-3204, USA.
Nature. 2002 Jul 4;418(6893):76-9. doi: 10.1038/nature00843.
The cytoplasmically inherited bacterium Wolbachia pipientis is a widespread parasite of arthropods that manipulates the reproductive biology of its hosts, often to their detriment, in order to foster its own transmission through egg cytoplasm. Here we report that infection by Wolbachia restores fertility to Drosophila melanogaster mutant females prevented from making eggs by protein-coding lesions in Sex-lethal (Sxl), the master regulator of sex determination. Suppression of sterility by Wolbachia discriminates markedly among similar germline-specific Sxl alleles, and is not observed for mutations in other genes that produce similar 'tumorous ovary' phenotypes, including one that blocks Sxl germline expression. This allele and gene specificity indicates that suppression probably results from a specific interaction with Sxl protein, rather than from a bypass of the normal germline requirement for this developmental regulator or from an effect on Sxl expression. The Sxl-Wolbachia interaction provides a rare opportunity to explore host-parasite relationships at the molecular level in a model insect. Furthermore, demonstration that a parasite infection can counteract the deleterious effects of mutations in host genes illustrates how hosts might become dependent on parasites.
胞质遗传细菌沃尔巴克氏体是节肢动物中广泛存在的寄生虫，它会操纵宿主的生殖生物学，通常对宿主有害，以促进自身通过卵细胞质进行传播。我们在此报告，沃尔巴克氏体感染可恢复黑腹果蝇突变雌性的生育能力，这些雌性因性别致死基因（Sxl）（性别决定的主要调节因子）中的蛋白质编码损伤而无法产卵。沃尔巴克氏体对不育的抑制在相似的种系特异性Sxl等位基因之间有明显差异，而在其他产生类似“肿瘤卵巢”表型的基因（包括一个阻断Sxl种系表达的基因）发生突变时则未观察到这种抑制现象。这种等位基因和基因特异性表明，抑制可能是由于与Sxl蛋白的特定相互作用，而不是绕过对该发育调节因子的正常种系需求，也不是对Sxl表达的影响。Sxl与沃尔巴克氏体的相互作用为在模式昆虫中从分子水平探索宿主 - 寄生虫关系提供了难得的机会。此外，证明寄生虫感染可以抵消宿主基因突变的有害影响，说明了宿主可能如何变得依赖寄生虫。
