Germ granules are biomolecular condensates present in most animal germ cells. One function of germ granules is to help maintain germ cell totipotency by organizing mRNA regulatory machinery, including small RNA-based gene regulatory pathways. The C. elegans germ granule is compartmentalized into multiple subcompartments whose biological functions are largely unknown. Here, we identify an uncharted subcompartment of the C. elegans germ granule, which we term the E granule. The E granule is nonrandomly positioned within the germ granule. We identify five proteins that localize to the E granule, including the RNA-dependent RNA polymerase (RdRP) EGO-1, the Dicer-related helicase DRH-3, the Tudor domain-containing protein EKL-1, and two intrinsically disordered proteins, EGC-1 and ELLI-1. Localization of EGO-1 to the E granule enables synthesis of a specialized class of 22G RNAs, which derive exclusively from 5’ regions of a subset of germline-expressed mRNAs. Defects in E granule assembly elicit disordered production of endogenous siRNAs, which disturbs fertility and the RNAi response. Our results define a distinct subcompartment of the C. elegans germ granule and suggest that one function of germ granule compartmentalization is to facilitate the localized production of specialized classes of small regulatory RNAs.

生殖颗粒是大多数动物生殖细胞中存在的生物分子凝聚物。生殖颗粒的一项功能是通过组织 mRNA 调节机制（包括基于小 RNA 的基因调节途径）来帮助维持生殖细胞的全能性。线虫胚芽颗粒被分成多个子区室，其生物学功能很大程度上未知。在这里，我们确定了秀丽隐杆线虫胚芽颗粒的一个未知的子区室，我们将其称为 E 颗粒。 E 颗粒非随机地位于胚芽颗粒内。我们鉴定了定位于 E 颗粒的五种蛋白质，包括 RNA 依赖性 RNA 聚合酶 (RdRP) EGO-1、Dicer 相关解旋酶 DRH-3、包含 Tudor 结构域的蛋白质 EKL-1 和两种本质上无序的蛋白质， EGC-1 和 ELLI-1。 EGO-1 定位到 E 颗粒能够合成一类特殊的 22G RNA，这些 RNA 完全源自种系表达 mRNA 子集的 5 '区域。 E 颗粒组装缺陷会引起内源 siRNA 产生紊乱，从而扰乱生育力和 RNAi 反应。我们的结果定义了秀丽隐杆线虫胚芽颗粒的一个独特的子区室，并表明胚芽颗粒区室化的一个功能是促进特定类别的小调节RNA的局部生产。