The Bovine Immunodeficiency Virus Rev Protein: Identification of a Novel Lentiviral Bipartite Nuclear Localization Signal Harboring an Atypical Spacer Sequence
The Bovine Immunodeficiency Virus Rev Protein: Identification of a Novel Lentiviral Bipartite Nuclear Localization Signal Harboring an Atypical Spacer Sequence
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DOI：
10.1128/jvi.01613-09
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发表时间：
2009-12-15
影响因子：
5.4
通讯作者：
Archambault, Denis
中科院分区：
文献类型：
--
作者：
Corredor, Andrea Gomez;Archambault, Denis
牛免疫缺陷病毒（BIV） Rev蛋白（长度为186个氨基酸[aa]）参与部分剪接和未剪接的病毒rna的核输出。先前的研究表明，BIV Rev定位于感染细胞的细胞核和核仁中。本文报道了该蛋白的核/核仁定位信号（NLS/NoLS）的表征。通过将BIV Rev的一系列缺失突变体转染到增强的绿色荧光蛋白上并进行荧光显微镜分析，我们能够绘制出该蛋白的aa 71和110之间的NLS区域。值得注意的是，通过在a71 - 110序列中进行丙氨酸替换，我们证明了BIV Rev NLS是二部的，映射到a71 - 74和95 - 101，主要由精氨酸残基组成。这是慢病毒/逆转录病毒中首次报道的双部Rev（或Rev样）NLS。此外，该NLS是非典型的，因为构成二部NLS的基序之间的序列长度为20aa，例如间隔序列。进一步的诱变实验还发现了BIV rev的NoLS区域，它主要定位在NLS间隔序列内。此外，BIV Rev NoLS序列不同于其他病毒和细胞核仁蛋白的共识序列。总之，我们得出结论，BIV Rev的核仁和核定位是通过新的NLS和NoLS基序介导的。
The bovine immunodeficiency virus (BIV) Rev protein (186 amino acids [aa] in length) is involved in the nuclear exportation of partially spliced and unspliced viral RNAs. Previous studies have shown that BIV Rev localizes in the nucleus and nucleolus of infected cells. Here we report the characterization of the nuclear/nucleolar localization signals (NLS/NoLS) of this protein. Through transfection of a series of deletion mutants of BIV Rev fused to enhanced green fluorescent protein and fluorescence microscopy analyses, we were able to map the NLS region between aa 71 and 110 of the protein. Remarkably, by conducting alanine substitution of basic residues within the aa 71 to 110 sequence, we demonstrated that the BIV Rev NLS is bipartite, maps to aa 71 to 74 and 95 to 101, and is predominantly composed of arginine residues. This is the first report of a bipartite Rev (or Rev-like) NLS in a lentivirus/retrovirus. Moreover, this NLS is atypical, as the length of the sequence between the motifs composing the bipartite NLS, e. g., the spacer sequence, is 20 aa. Further mutagenesis experiments also identified the NoLS region of BIV Rev. It localizes mainly within the NLS spacer sequence. In addition, the BIV Rev NoLS sequence differs from the consensus sequence reported for other viral and cellular nucleolar proteins. In summary, we conclude that the nucleolar and nuclear localizations of BIV Rev are mediated via novel NLS and NoLS motifs.