A domain of human immunodeficiency virus type 1 Vpr containing repeated H(S/F)RIG amino acid motifs causes cell growth arrest and structural defects.

Vpr is a virion-associated protein of human immunodeficiency type 1 (HIV-1) whose function in acquired immunodeficiency syndrome (AIDS) has been uncertain. Employing the yeast Saccharomyces cerevisiae as a model to examine the effects of HIV-1 auxiliary proteins on basic cellular functions, we found that the vpr gene caused cell growth arrest and structural defects indicated by osmotic sensitivity and gross cell enlargement. Production of various domains by gene expression showed that this effect arose from within the carboxyl-terminal third of the Vpr protein and implicated the sequence HFRIGCRHSRIG, containing two H(S/F)RIG motifs. Electroporation with a series of peptides containing these motifs caused structural defects in yeast that resulted in osmotic sensitivity. A protein with functions relating to the yeast cytoskeleton, Sac1p [Cleves, A. E., Novick, P.J. & Bankaitis, V.A. (1989) J. Cell Biol. 109, 2939-2950], shows sequence similarity to Vpr, and Vpr's effect in yeast may be to disrupt normal Sac1p functions. The Sac1p equivalent has not yet been described in mammalian cells, but in rhabdomyosarcoma and osteosarcoma cell lines Vpr also caused gross cell enlargement and replication arrest [Levy, D.N., Fernandes, L.S., Williams, W.V. & Weiner, D.B. (1993) Cell 72, 541-550]. We note that there is a correlation between the region containing the H(S/F)RIG motifs and the pathogenicity of primate lentiviruses and we suggest that the function of Vpr may be to bring about cell growth arrest and/or cytoskeletal changes as an early step in HIV-1 infection. IMAGES:

Vpr是人类免疫缺陷病毒1型（HIV-1）的病毒粒子相关蛋白，其在获得性免疫缺陷综合征（AIDS）中的功能迄今尚未明确。本研究以酿酒酵母（Saccharomyces cerevisiae）为模型，探究HIV-1辅助蛋白对细胞基础功能的影响，结果发现vpr基因可引发细胞生长阻滞，并伴随渗透压敏感性升高与显著细胞肿大等结构缺陷。通过基因表达构建不同结构域的实验表明，该效应源自Vpr蛋白羧基末端三分之一区域，且涉及包含两个H(S/F)RIG基序的序列HFRIGCRHSRIG。将携带这些基序的一系列多肽进行电穿孔处理后，可诱导酵母产生结构缺陷并引发渗透压敏感性。有一种与酵母细胞骨架功能相关的蛋白Sac1p[Cleves, A. E., Novick, P.J. & Bankaitis, V.A. (1989) J. Cell Biol. 109, 2939-2950]，其序列与Vpr存在相似性，因此Vpr在酵母中的效应可能是通过干扰正常Sac1p功能实现的。目前尚未在哺乳动物细胞中发现Sac1p的同源蛋白，但在横纹肌肉瘤与骨肉瘤细胞系中，Vpr同样可引发显著细胞肿大与复制阻滞[Levy, D.N., Fernandes, L.S., Williams, W.V. & Weiner, D.B. (1993) Cell 72, 541-550]。我们注意到，包含H(S/F)RIG基序的区域与灵长类慢病毒的致病性存在相关性，并据此提出假说：Vpr的功能可能是介导细胞生长阻滞和/或细胞骨架改变，以此作为HIV-1感染的早期环节。图片：