Conformational Landscape of the HIV-1 Envelope Glycoproteins

项目摘要/摘要 人类免疫缺陷病毒(HIV-1)进入宿主细胞是由包膜糖蛋白介导的 (环境)三聚体。Env三聚体由三个非共价结合的gp120外膜糖蛋白组成。 三种gp41糖蛋白，固定在病毒膜上，具有较长的(~145个残基) 细胞质的尾巴。作为病毒表面唯一的病毒特异性分子，env是宿主的主要靶标。 中和抗体。环境构象的灵活性对于病毒的入侵是必不可少的，也有助于 HIV-1逃避宿主抗体反应的能力。在病毒进入期间，gp120与受体的结合， CD4和CCR5/CXCR4，触发亚稳态环境的构象变化，最终导致gp41- 介导的病毒和靶细胞膜的融合。HIV-1病毒粒子上的包膜至少有可能是样本 三种构象：“封闭的”预激构象(状态1)、“开放的”结合CD4的构象(状态 3)和中间的“部分开放”构象(状态2)。在受体参与之前，State-1 Env 构象受到能量的青睐，使最初的HIV-1毒株相对抵抗结合 潜在的中和抗体。CD4绑定将Env从状态1驱动到状态2，然后进入状态3， 发夹前中间体。State-3Env与CCR5或CXCR4共受体结合促进形成 高度稳定的gp41六螺旋束，导致病毒膜和靶细胞膜的融合。 多项观察表明，State-1 Env构象是亚稳定的，很容易被 环境病毒序列的改变或从膜环境中提取环境病毒。事实上，稳定的可溶性 已经显示了gp140三聚体或洗涤剂增溶的环境三聚体，其详细结构可用 采用类似国家2的构象！拟议的工作将解决我们目前不完整的理解 国家-1环境构象的。尽管HIV-1具有巨大的变异性，但它如何保持国家-1环境 构象？我们之前已经证明，多个环境氨基酸残基的变化可以扰乱 状态-1构象。在拟议的研究中，我们将确定自然多态的环境残基，当 改变，稳定功能状态-1构象。我们将评估State-1-稳定和State-1- 环境病毒的不稳定变化相互作用来决定病毒的表型。这些研究的重点之一将是 Gp41膜-近端外区(MPER)构象与血管内皮细胞生长的关系 环境胞外结构域其余部分的构象。 State-1 env构象的亚稳定性阻碍了其在免疫系统中的表达 自然感染艾滋病毒-1和接种疫苗后。拟议的研究将为生产纯净品的努力提供参考 HIV-1环境三聚体稳定在State-1构象中，这是广泛中和的主要目标 抗体和有效的小分子进入抑制剂。了解State-1环境的构象是什么 监管机构应加快环境导向疗法和疫苗的设计。

PROJECT SUMMARY/ABSTRACT The entry of human immunodeficiency virus (HIV-1) into host cells is mediated by the envelope glycoprotein (Env) trimer. The Env trimer consists of three gp120 exterior glycoproteins non-covalently associated with three gp41 glycoproteins, which are anchored in the viral membrane and which possess long (~145-residue) cytoplasmic tails. As the only virus-specific molecule on the viral surface, Env is the major target for host neutralizing antibodies. Env conformational flexibility is essential for virus entry and also contributes to the ability of HIV-1 to evade the host antibody response. During virus entry, the binding of gp120 to the receptors, CD4 and CCR5/CXCR4, triggers conformational changes in the metastable Env that ultimately result in gp41- mediated fusion of the viral and target cell membranes. The HIV-1 Env on virions potentially samples at least three conformations: a “closed” pretriggered conformation (State 1), an “open” CD4-bound conformation (State 3), and an intermediate “partially open” conformation (State 2). Prior to receptor engagement, the State-1 Env conformation is energetically favored, rendering primary HIV-1 strains relatively resistant to the binding of potentially neutralizing antibodies. CD4 binding drives Env from State 1 to State 2 and then into State 3, the prehairpin intermediate. Binding of the State-3 Env to the CCR5 or CXCR4 coreceptor promotes the formation of the highly stable gp41 six-helix bundle, resulting in the fusion of the viral and target cell membranes. Multiple observations indicate that the State-1 Env conformation is metastable and easily disrupted by alteration of Env sequences or extraction of Env from a membrane environment. Indeed, stabilized soluble gp140 trimers or detergent-solubilized Env trimers for which detailed structures are available have been shown to adopt a State-2-like conformation! The proposed work will address our currently incomplete understanding of the State-1 Env conformation. How does HIV-1, despite its tremendous variability, maintain a State-1 Env conformation? We have previously shown that changes in multiple Env amino acid residues can disrupt the State-1 conformation. In the proposed studies, we will identify naturally polymorphic Env residues that, when changed, stabilize the functional State-1 conformation. We will evaluate how State-1-stabilizing and State-1- destabilizing changes in Env interact to determine viral phenotypes. One focus of these studies will be the relationship between the conformation of the gp41 membrane-proximal external region (MPER) and the conformation of the rest of the Env ectodomain. The metastability of the State-1 Env conformation impedes its presentation to the host immune system during natural HIV-1 infection and following vaccination. The proposed studies will inform efforts to produce purified HIV-1 Env trimers stabilized in a State-1 conformation, which serves as the major target of broadly neutralizing antibodies and potent small-molecule entry inhibitors. Understanding how the State-1 Env conformation is regulated should expedite the design of Env-directed therapies and vaccines.