Structure and Mechanism of Eukaryotic Transcription Regulation

总结 转录是读出存储在染色体中的遗传信息的第一步。在真核生物中， 三种多亚基RNA聚合酶（Pos）Pol I、II和III转录25 S核糖体RNA（rRNA）， 编码蛋白质的RNA和短的非编码RNA，如转运RNA（tRNA）和25 S rRNA基因。一 50多年来积累的大量遗传和生物化学数据揭示了大多数 参与者和复杂的监管电路的细节。新教徒的招募和集会 启动子上的复合物代表了基因表达过程中的关键调控步骤之一。Pol II启动 转录机制包括激活子结合的介体沿着一系列的通用转录因子（GTF） （TFIID、TFIIA、TFIIB、TFIIE、TFIIF和TFIIH），其组装成约4兆道尔顿（MDa）的预起始 核心启动子DNA上的PIC复合物。另一方面，Pol III酶被募集到其启动子上， 相应GTF（TFIIIC、TBP、BRF 1和B“）的帮助。本提案旨在调查 通过直接观察这些转录活性起始， 复合物使用单粒子cryo-EM。这些不同但在进化上相关的 系统在基因调控的这一关键步骤将提供一个前所未有的，全面的看法，这一关键 在分子生物学的中心法则过程。

Summary Transcription is the first step to read out the genetic information stored in the chromosome. In eukaryotes, three multi-subunit RNA polymerases (Pols), Pol I, II, and III transcribe the 25S ribosomal RNA (rRNA), protein-coding, and short non-coding RNAs such as transfer RNA (tRNA) and 25S rRNA genes, respectively. A wealth of genetic and biochemical data accumulated over 50 years have uncovered most of the molecular players involved and details of the intricate regulatory circuits. The recruitment and assembly of the initiation complex at the promoter represent one of the key regulatory steps during gene expression. The Pol II initiation machinery includes the activator-bound Mediator along with a series of general transcription factors (GTFs) (TFIID, TFIIA, TFIIB, TFIIE, TFIIF, and TFIIH) that assemble into a ~4-megadalton (MDa) pre-initiation complex (PIC) on core promoter DNA. On the other hand, the Pol III enzyme is recruited onto its promoter with the help of corresponding GTFs (TFIIIC, TBP, BRF1, and B''). This proposal aims to investigate the mechanism of transcription regulation by directly visualizing these transcriptional competent initiation complexes using single-particle cryo-EM. Comparable pictures of these different but evolutionarily related systems at this critical step of gene regulation will provide an unprecedented, comprehensive view of this key process in the central dogma of molecular biology.