Berkowitz R D, Ohagen A, Höglund S, Goff S P
Department of Microbiology, Columbia University, New York, New York 10032, USA.
J Virol. 1995 Oct;69(10):6445-56. doi: 10.1128/JVI.69.10.6445-6456.1995.
The retroviral nucleocapsid (NC) protein is necessary for the specific encapsidation of the viral genomic RNA by the assembling virion. However, it is unclear whether NC contains the determinants for the specific recognition of the viral RNA or instead contributes nonspecific RNA contacts to strengthen a specific contact made elsewhere in the Gag polyprotein. To discriminate between these two possibilities, we have swapped the NC domains of the human immunodeficiency virus type 1 (HIV-1) and Moloney murine leukemia virus (M-MuLV), generating an HIV-1 mutant containing the M-MuLV NC domain and an M-MuLV mutant containing the HIV-1 NC domain. These mutants, as well as several others, were characterized for their abilities to encapsidate HIV-1, M-MuLV, and nonviral RNAs and to preferentially package genomic viral RNAs over spliced viral RNAs. We found that the M-MuLV NC domain mediates the specific packaging of RNAs containing the M-MuLV psi packaging element, while the HIV-1 NC domain confers an ability to package the unspliced HIV-1 RNA over spliced HIV-1 RNAs. In addition, we found that the HIV-1 mutant containing the M-MuLV NC domain exhibited a 20-fold greater ability than wild-type HIV-1 to package a nonviral RNA. These results help confirm the notion that the NC domain specifically recognizes the retroviral genomic RNA during RNA encapsidation.
逆转录病毒核衣壳（NC）蛋白对于组装中的病毒体特异性包裹病毒基因组RNA是必需的。然而，尚不清楚NC是否包含病毒RNA特异性识别的决定因素，或者相反，它是否有助于非特异性RNA接触以加强在Gag多蛋白其他部位形成的特异性接触。为了区分这两种可能性，我们交换了1型人类免疫缺陷病毒（HIV-1）和莫洛尼鼠白血病病毒（M-MuLV）的NC结构域，产生了一个含有M-MuLV NC结构域的HIV-1突变体和一个含有HIV-1 NC结构域的M-MuLV突变体。对这些突变体以及其他几个突变体进行了表征，以研究它们包裹HIV-1、M-MuLV和非病毒RNA的能力，以及优先包装基因组病毒RNA而非剪接病毒RNA的能力。我们发现，M-MuLV NC结构域介导了含有M-MuLV ψ包装元件的RNA的特异性包装，而HIV-1 NC结构域赋予了优先包装未剪接HIV-1 RNA而非剪接HIV-1 RNA的能力。此外，我们发现含有M-MuLV NC结构域的HIV-1突变体包装非病毒RNA的能力比野生型HIV-1高20倍。这些结果有助于证实NC结构域在RNA包裹过程中特异性识别逆转录病毒基因组RNA的观点。
