Nuclear import, virion incorporation, and cell cycle arrest/differentiation are mediated by distinct functional domains of human immunodeficiency virus type 1 Vpr
Nuclear import, virion incorporation, and cell cycle arrest/differentiation are mediated by distinct functional domains of human immunodeficiency virus type 1 Vpr
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DOI：
10.1128/jvi.71.9.6339-6347.1997
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发表时间：
1997-09-01
影响因子：
5.4
通讯作者：
Weiner, DB
中科院分区：
文献类型：
--
作者：
Mahalingam, S;Ayyavoo, V;Weiner, DB
人类免疫缺陷病毒1型（HIV-1）的vpr基因产物是一种病毒体相关蛋白，对于单核细胞/巨噬细胞中的有效病毒复制至关重要。Vpr在没有其他病毒蛋白的情况下表达时主要定位于细胞核中。Vpr通过与Gag前体多聚蛋白p55（gag）的p6结构域相互作用而被有效地包装到病毒颗粒中。我们开发了一个面板的表达载体编码Vpr分子突变的氨基末端螺旋结构域，亮氨酸-异亮氨酸（LR）结构域，和羧基末端结构域映射不同的功能域，并定义之间的相互关系病毒粒子掺入，核定位，细胞周期阻滞，和分化功能的Vpr。我们观察到Vpr的N-末端结构域中的取代突变损害了核定位和病毒体包装，这表明螺旋结构可能在调节这两种生物学特性中起着至关重要的作用。LR结构域被发现参与Vpr的核定位。相比之下，细胞周期停滞似乎在很大程度上是由Vpr的C-末端结构域控制的。LR和C-末端结构域似乎不是Vpr病毒体掺入所必需的。有趣的是，我们发现两个Vpr突变体（A30 L和G75 A）的单一氨基酸取代保留了易位到细胞核的能力，但在细胞周期阻滞功能受损。相比之下，Leu 68突变为Ser导致定位于细胞质中的蛋白质，同时保留阻止宿主细胞增殖的能力。我们推测，核定位和细胞周期阻滞功能的Vpr是不相关的，这些功能是介导的可分离的推定功能域Vpr。
The vpr gene product of human immunodeficiency virus type 1 (HIV-1) is a virion-associated protein that is essential for efficient viral replication in monocytes/macrophages. Vpr is primarily localized in the nucleus when expressed in the absence of other viral proteins. Vpr is packaged efficiently into viral particles through interactions with the p6 domain of the Gag precursor polyprotein p55(gag). We developed a panel of expression vectors encoding Vpr molecules mutated in the amino-terminal helical domain, leucine-isoleucine (LR) domain, and carboxy-terminal domain to map the different functional domains and to define the interrelationships between virion incorporation, nuclear localization, cell cycle arrest, and differentiation functions of Vpr. We observed that substitution mutations in the N-terminal domain of Vpr impaired both nuclear localization and virion packaging, suggesting that the helical structure may play a vital role in modulating both of these biological properties. The LR domain was found to be involved in the nuclear localization of Vpr. In contrast, cell cycle arrest appears to be largely controlled by the C-terminal domain of Vpr. The LR and C-terminal domains do not appear to be essential for virion incorporation of Vpr. Interestingly, we found that two Vpr mutants harboring single amino acid substitutions (A30L and G75A) retained the ability to translocate to the nucleus but were impaired in the cell cycle arrest function. In contrast, mutation of Leu68 to Ser resulted in a protein that localizes in the cytoplasm while retaining the ability to arrest host cell proliferation. We speculate that the nuclear localization and cell cycle arrest functions of Vpr are not interrelated and that these functions are mediated by separable putative functional domains of Vpr.