Project 2 - Nuclear Export and Translation

HIV-1 RNA从细胞核的转运及其在细胞质中的调节表达是HIV-1感染的关键步骤。 病毒的生命周期存在于病毒RNA中的结构域已被证明调节这些事件;即， 未剪接转录本的转录需要Rev反应元件，RRE; 5 '-前导序列的替代构象 区域决定翻译与包装的命运;以及遗传信息的重新编码， 固定比例的病毒蛋白的产生依赖于移码信号。虽然这些RNA的阐明 结构，从而调节这些事件的机制，更接近于实现，在CRNA中进行的研究 1.0已经确定，核出口和转化监管都比 以前认为。有几个重大发现是以前没有预测或设想到的： Gag：RRE相互作用;转录起始位点异质性的存在及其对 保持5 '-前导结构的单独池;以及在一个或多个前导结构之间存在结构平衡。 非活性茎环和活性的、允许移码的假结构象。基于这些CRNA 发现，该项目旨在获得一个完整的结构和机制的理解，核 HIV-1的转运和翻译调节，结合结构研究和可视化，生物化学 和病毒学实验我们了解核出口的目的是确定高分辨率 RRE核输出信号的结构，Gag：RRE相互作用的生物学意义，以及 各种HIV-1 RNA的核输出特性。我们理解翻译调控的目的是 确定5 '-前导序列的单体和剪接的env mRNA形式的结构， 参与程序性核糖体移码过程。

Transport of HIV-1 RNAs from the nucleus and their regulated expression in the cytoplasm are critical steps of the viral lifecycle. Domains present in viral RNA have been shown to regulate these events; namely, the export of unspliced transcripts requires the Rev responsive element, RRE; alternative conformers of the 5'-leader region dictate translation vs. packaging fates; and the recoding of genetic information that allows the production of fixed ratios of viral proteins relies on the frameshifting signal. While elucidation of these RNA structures, and thus mechanisms regulating these events, are closer to realization, studies carried out in CRNA 1.0 have established that both nuclear export and translational regulation are more multifaceted than previously thought. Several major discoveries were not previously predicted or envisioned: the cytoplasmic Gag:RRE interaction; the presence of transcriptional start site heterogeneity, and its consequence on maintaining separate pools of 5'-leader structures; and the presence of a structural equilibrium between an inactive stem-loop and an active, frameshift-permissive pseudoknot conformation. Based on these CRNA discoveries, this project aims to gain a complete structural and mechanistic understanding of both nuclear transport and translational regulation in HIV-1 by combining structural studies with visualization, biochemical and virologic experiments. Our aims for understanding nuclear export will be to determine the high resolution structures of the RRE nuclear export signal, the biological significance of Gag:RRE interactions, and the nuclear export properties of various HIV-1 RNAs. Our aims for understanding translational regulation will be to determine structures for the monomeric and the spliced env mRNA forms of the 5'-leader, and the structures involved in the process of programmed ribosomal frameshifting.