Structural Studies of the Eukaryotic Transcription Initiation Machinery

基因表达的转录调控是一项复杂的任务，对生长至关重要 以及存活，无论是作为受精卵发育过程的一部分，还是 在适应变化的环境条件时。转录起始步骤是 可以说是基因转录中最受调控的步骤，因为微调其速率和 同步性可以作为在整个生物体范围内产生基因变化的关键控制点 对发育和环境提示作出反应的表达模式。 不足为奇的是，基因调控电路的复杂性与其大小是平行的 以及参与转录启动的分子玩家的复杂性。在过去的时间里 30年来，生物化学、分子遗传学和体内研究揭示了大多数 不是所有的，而是转录装置的中心组件。然而，a 对人类基因表达的机械性理解构成了一个巨大的挑战 而且远远落后于。一个主要的障碍是转录机制 由100多个单独的多肽组成，它们作为一个巨大的、动态的 由功能不同的多亚单位复合体组成的组合体，其中许多仅 可从内源获得的。我们正在使用单粒子电磁重建来 描述大型人类建筑群的结构、动力学和相互作用 对基因调控是必不可少的。3D低温电磁重建是一种理想的适合于 这项任务，因为它需要有限的材料，是非常大的研究的最佳选择 组件，并具有检测和表征构象灵活性的潜力， 一个属性可能被证明是关键的，以能够描述 像TFIID这样的转录复合体，是这一过程中的关键枢纽，需要结合 不同的DNA核心启动子，并整合来自大量不同 转录激活因子和辅因子。 对基因的基本了解对人类健康的意义 转录是开启和关闭的，怎么夸张都不为过。这样的意义就是 突出的事实是各种癌症的发展伴随着 导致疾病各个方面的基因表达变化，以及由 诱导多能干细胞的发现，其中3-4的全局表达 转录激活剂足以引入所需的基因表达变化 过渡到一种多能状态。通过了解必需的蛋白质结构 基因激活，我们将指导未来的研究开发新的治疗方法 其目标是控制介导细胞生长、肿瘤、转移的基因表达， 和血管生成在人类或那些旨在促进诱导的 多能干细胞研究进入临床。

Transcriptional regulation of gene expression is a complex task, critical for growth and survival, whether as part of the developmental process from the fertilized egg, or when adapting to changing environmental conditions. The transcription initiation step is arguably the most regulated step in gene transcription, as fine tuning both its rate and synchrony can serve as a key control point to produce organism-wide changes in gene expression profiles in response to developmental and environmental cues. Not surprisingly, the complexity of gene regulatory circuitries is paralleled by the size and complexity of the molecular players involved in transcription initiation. Over the past 30 years, biochemistry, molecular genetics, and in vivo studies have uncovered most, if not all, of the central components of the transcriptional apparatus. However, a mechanistic understanding of gene expression in humans poses a formidable challenge and lags dramatically behind. A major obstacle is that the transcriptional machinery comprises more than 100 individual polypeptides that operate as a huge and dynamic assemblage made up of functionally distinct multi-subunit complexes, many of them only accessible from endogenous sources. We are using single particle EM reconstruction to characterize the architecture, dynamics and interactions of large human complexes essential for gene regulation. 3D Cryo-EM reconstruction is a technique ideally suited to this task, as it requires limited amounts of material, is optimal to study very large assemblies, and is has the potential to detect and characterize conformational flexibility, a property to may prove critical to be able to describe the functional plasticity required in transcriptional complexes like TFIID, an essential hub in this process that needs to bind to different DNA core promoters and integrate the input from a large variety of transcriptional activators and cofactors. The significance to human health of a fundamental understanding of how gene transcription is switched on and off cannot be overstated. Such significance is highlighted by the fact that development of various cancers is accompanied by alterations in gene expression leading to various aspects of the disease, and by the discovery of induced pluripotent stem cells, where the expression of 3-4 global transcriptional activators is sufficient to introduce gene expression changes needed to transition into a pluripotent state. By understanding the protein structures necessary for gene activation, we will guide future research into the development of novel treatments that target the control of gene expression mediating cell growth, neoplasia, metastasis, and angiogenesis in humans or those aimed at facilitating the transition of induced pluripotent stem cells research into the clinic.