European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, Heidelberg, Germany.
Candidate for joint PhD degree from EMBL and Heidelberg University, Faculty of Biosciences, Heidelberg, Germany.
Nat Struct Mol Biol. 2021 Feb;28(2):210-219. doi: 10.1038/s41594-020-00555-5. Epub 2021 Feb 8.
RNA polymerase III (Pol III) synthesizes transfer RNAs and other short, essential RNAs. Human Pol III misregulation is linked to tumor transformation, neurodegenerative and developmental disorders, and increased sensitivity to viral infections. Here, we present cryo-electron microscopy structures at 2.8 to 3.3 Å resolution of transcribing and unbound human Pol III. We observe insertion of the TFIIS-like subunit RPC10 into the polymerase funnel, providing insights into how RPC10 triggers transcription termination. Our structures resolve elements absent from Saccharomyces cerevisiae Pol III such as the winged-helix domains of RPC5 and an iron-sulfur cluster, which tethers the heterotrimer subcomplex to the core. The cancer-associated RPC7α isoform binds the polymerase clamp, potentially interfering with Pol III inhibition by tumor suppressor MAF1, which may explain why overexpressed RPC7α enhances tumor transformation. Finally, the human Pol III structure allows mapping of disease-related mutations and may contribute to the development of inhibitors that selectively target Pol III for therapeutic interventions.
RNA 聚合酶 III（Pol III）合成转移 RNA 和其他短的、必需的 RNA。人类 Pol III 的失调与肿瘤转化、神经退行性和发育障碍以及对病毒感染的敏感性增加有关。在这里，我们呈现了转录和未结合的人 Pol III 的 2.8 至 3.3Å 分辨率的冷冻电子显微镜结构。我们观察到 TFIIS 样亚基 RPC10 插入聚合酶漏斗，深入了解 RPC10 如何触发转录终止。我们的结构解决了酿酒酵母 Pol III 中不存在的元素，例如 RPC5 的翼型螺旋结构域和一个铁硫簇，该簇将三聚体亚基复合物固定在核心上。与癌症相关的 RPC7α 同工型结合聚合酶夹，可能干扰肿瘤抑制因子 MAF1 对 Pol III 的抑制，这可能解释了为什么过度表达的 RPC7α 增强了肿瘤转化。最后，人类 Pol III 结构允许对与疾病相关的突变进行映射，并可能有助于开发选择性针对 Pol III 的抑制剂，以进行治疗干预。
