A structurally disordered region at the C terminus of capsid plays essential roles in multimerization and membrane binding of the Gag protein of human immunodeficiency virus type 1
A structurally disordered region at the C terminus of capsid plays essential roles in multimerization and membrane binding of the Gag protein of human immunodeficiency virus type 1
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DOI：
10.1128/jvi.77.3.1772-1783.2003
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发表时间：
2003-02-01
影响因子：
5.4
通讯作者：
Wainberg, MA
中科院分区：
文献类型：
--
作者：
Liang, C;Hu, J;Wainberg, MA
人类免疫缺陷病毒I型（HIV-1）衣壳蛋白（CA）的晶体结构揭示了最后11个c端氨基酸的紊乱。这一紊乱区域包含一个富含甘氨酸的序列353-GVGGP-357（编号是指Gag的起始蛋氨酸），该序列在HIV-1、HIV-2和猴免疫缺陷病毒的Gag蛋白中高度保守，这表明该序列在病毒复制中的重要性。在目前的研究中，我们证明，在全长HIV-1基因组的背景下，改变这一短区域内的任何单个残基实际上都可以消除细胞外病毒颗粒的产生，无论是否存在病毒蛋白酶活性。正如梯度沉降和膜浮选离心试验的结果所证明的那样，这种病毒颗粒产生的严重缺陷是由于Gag多聚化受损，以及Gag与细胞膜的结合减少。与野生型Gag在质膜上的点状分布相反，突变型Gag在细胞质内的弥漫性分布模式进一步支持了这些发现。在这些结果的基础上，我们提出氨基酸拉伸353-GVGGP-357在CA晶体形式中的无序特征可能允许Gag采用多种构象，并且这种结构灵活性是Gag为了构建几何复杂的颗粒所需要的。
Crystal structures of human immunodeficiency virus type I (HIV-1) capsid protein (CA) reveal that the last 11 C-terminal amino acids are disordered. This disordered region contains a glycine-rich sequence 353-GVGGP-357 (numbering refers to the initiation methionine of Gag) that is highly conserved within the Gag proteins of HIV-1, HIV-2, and simian immunodeficiency virus, which suggests the importance of this sequence in virus replication. In the present study, we demonstrate that changing any individual residue within this short region in the context of the full-length HIV-1 genome virtually abolishes production of extracellular virus particles, in either the presence or absence of viral protease activity. This severe defect in virus particle production results from impaired Gag multimerization, as well as from decreased Gag association with the cellular membranes, as demonstrated by the results of gradient sedimentation and membrane flotation centrifugation assays. These findings are further supported by the diffuse distribution pattern of the mutant Gag within the cytoplasm, as opposed to the punctate distribution of the wild-type Gag on the plasma membrane. On the basis of these results, we propose that the disordered feature of amino acid stretch 353-GVGGP-357 in the CA crystal forms may have allowed Gag to adopt multiple conformations and that such structural flexibility is needed by Gag in order to construct geometrically complex particles.