LOW RESOLUTION STRUCTURES OF HIV-1 5' -UTR AND THE NATIVE DIMER

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 在复制过程中，HIV-1病毒从包含大量细胞和剪接病毒RNA的细胞池中选择性地包装两个拷贝的全长未剪接RNA基因组。二聚体基因组包装的原因和识别其自身RNA的机制仍不清楚。了解基因组包装机制对于开发新的抗艾滋病策略至关重要。最近的体内研究表明，HIV-15的全长5‘-非翻译区(UTR)和Gag基因的上游编码区负责有效的基因组包装。然而，结晶困难和大分子尺寸(~110 kDa)给X射线结晶学和核磁共振表征带来了极大的困难(由于共振重叠和峰加宽)。 小角X射线散射将为这种大的RNA提供有价值的低分辨率结构信息。1-3)比较单体和二聚体的5‘-UTR构象可以洞察基因组包装所涉及的构象变化。阳离子依赖的折叠可以用SAXS进一步研究。此外，广泛的遗传学和病毒学研究表明，基因组识别是由病毒Gag多蛋白核衣壳结构域介导的。早期的研究表明，NC蛋白与位于5‘-UTR的SL2和SL3茎环(Kd~140 nm)紧密结合。(参考文献)4-6)SAXS可以解决NC-RNA络合物的构象和结合化学结构。NC与单体和二聚体RNA结合的比较可以根据对二聚体RNA基因组的选择性包装来合理化。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. During the replication process, HIV-1 viruses selectively package two copies of their full-length unspliced RNA genomes from a cellular pool that contains a substantial excess of cellular and spliced viral RNAs. The reasons for the dimeric genome packaging and the mechanism for the recognition of its own RNAs still remain unclear. Understanding the genome packaging mechanism will be essential for the development of new anti-AIDS strategies. Recent in vivo studies have indicated that the full length HIV-1 5'-untranslated region (UTR) and upstream coding regions of the gag gene are responsible for efficient genome packaging. However, the difficulties in crystallization and the large molecular size (~110 kDa) has posed enormous difficulties for X-ray crystallography and NMR characterizations (due to the resonance overlap and peak broadening). Small angle X-ray scattering will provide valuable low resolution structural information for this large RNA.(Ref. 1-3) Comparing the monomeric and dimeric 5'-UTR conformations can provide insight on the conformational change involved upon genome packaging. Cation-dependent folding can further be investigated by SAXS. Besides, extensive genetic and virological studies indicate that the genome recognition is mediated by the viral Gag polyprotein nucleocapsid domain. Early studies have shown that NC protein binds tightly to the SL2 and SL3 stem loops (Kd ~ 140 nM) located in the 5'-UTR. (Ref. 4-6) The NC-RNA complex conformation and binding stoichemitry can be addressed by SAXS. Comparison of NC binding to monomeric and dimeric RNAs can be rationalized in terms of the selective packaging the dimeric RNA genome.