Viral Recombination Section, HIV Dynamics and Replication Program, National Cancer Institute at Frederick, Frederick, MD 21702;
Viral Recombination Section, HIV Dynamics and Replication Program, National Cancer Institute at Frederick, Frederick, MD 21702.
Proc Natl Acad Sci U S A. 2020 Mar 17;117(11):6145-6155. doi: 10.1073/pnas.1917590117. Epub 2020 Mar 4.
HIV-1 full-length RNA (HIV-1 RNA) plays a central role in viral replication, serving as a template for Gag/Gag-Pol translation and as a genome for the progeny virion. To gain a better understanding of the regulatory mechanisms of HIV-1 replication, we adapted a recently described system to visualize and track translation from individual HIV-1 RNA molecules in living cells. We found that, on average, half of the cytoplasmic HIV-1 RNAs are being actively translated at a given time. Furthermore, translating and nontranslating RNAs are well mixed in the cytoplasm; thus, Gag biogenesis occurs throughout the cytoplasm without being constrained to particular subcellular locations. Gag is an RNA binding protein that selects and packages HIV-1 RNA during virus assembly. A long-standing question in HIV-1 gene expression is whether Gag modulates HIV-1 RNA translation. We observed that despite its RNA-binding ability, Gag expression does not alter the proportion of translating HIV-1 RNA. Using single-molecule tracking, we found that both translating and nontranslating RNAs exhibit dynamic cytoplasmic movement and can reach the plasma membrane, the major HIV-1 assembly site. However, Gag selectively packages nontranslating RNA into the assembly complex. These studies illustrate that although HIV-1 RNA serves two functions, as a translation template and as a viral genome, individual RNA molecules carry out only one function at a time. These studies shed light on previously unknown aspects of HIV-1 gene expression and regulation.
HIV-1 全长 RNA（HIV-1 RNA）在病毒复制中起着核心作用，它既是 Gag/Gag-Pol 翻译的模板，又是子代病毒粒子的基因组。为了更好地理解 HIV-1 复制的调控机制，我们采用了最近描述的系统，以在活细胞中可视化和跟踪单个 HIV-1 RNA 分子的翻译。我们发现，平均而言，在给定时间内，有一半的细胞质 HIV-1 RNA 正在被积极翻译。此外，翻译和非翻译的 RNA 在细胞质中很好地混合；因此，Gag 生物发生发生在整个细胞质中，而不受特定亚细胞位置的限制。Gag 是一种 RNA 结合蛋白，它在病毒组装过程中选择和包装 HIV-1 RNA。HIV-1 基因表达中的一个长期存在的问题是 Gag 是否调节 HIV-1 RNA 翻译。我们观察到，尽管 Gag 具有 RNA 结合能力，但它的表达并不会改变翻译中的 HIV-1 RNA 的比例。通过单分子跟踪，我们发现翻译和非翻译的 RNA 都表现出细胞质的动态运动，并能到达质膜，这是 HIV-1 组装的主要部位。然而，Gag 选择性地将非翻译 RNA 包装到组装复合物中。这些研究表明，尽管 HIV-1 RNA 有两种功能，作为翻译模板和作为病毒基因组，但单个 RNA 分子一次只执行一种功能。这些研究阐明了 HIV-1 基因表达和调控的以前未知的方面。
