Conformational Landscape of the HIV-1 Envelope Glycoproteins

HIV-1 包膜糖蛋白的构象景观

• 批准号: 9220709
• 负责人: JOSEPH G SODROSKI
• 金额: $ 69.71万
• 依托单位: DANA-FARBER CANCER INST
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-02-15 至 2021-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9220709
• 关键词: Acquired Immunodeficiency Syndrome; Affect; Alpha Cell; Antibodies; Binding; Biological Process; Biology; CCR5 gene; CXCR4 gene; Cell membrane; Cells; Complex; Coupled; Cysteine; Dependence; Development; Elements; Event; Exposure to; Foundations; Freezing; Glycoproteins; Goals; HIV; HIV Envelope Protein gp120; HIV-1; Human; Immunocompetent; Intervention; Location; Mediating; Membrane; Membrane Fusion; Membrane Glycoproteins; Modeling; Modification; Molecular Conformation; Molecular Machines; Parents; Pathway interactions; Pharmaceutical Preparations; Potential Energy; Predisposition; Process; Property; Receptor Cell; Reducing Agents; Regulation; Sampling; Series; Shapes; Structure; Surface; Testing; Tropism; Vaccines; Variant; Viral; Virion; Virus; antibody inhibitor; conformational conversion; inhibitor/antagonist; insight; mutant; neutralizing antibody; novel; prototype; public health relevance; receptor; receptor binding; restraint; small molecule; therapy development

 DESCRIPTION (provided by applicant): The human immunodeficiency virus (HIV-1) envelope glycoproteins (Envs) mediate the entry of the virus into the host cell. The Env spike is the only virus-specific component exposed on the virus surface and thus represents a key target for small-molecule entry inhibitors and vaccine-induced antibodies. The Env spike is a trimer consisting of three gp120 exterior Envs and three gp41 transmembrane Envs. To evade host neutralizing antibodies, the unliganded Env spike assumes a "closed" conformation (State 1). During the virus entry process, the high potential energy stored in the closed Env conformation is channeled into the eventual fusion of the viral and target cell membranes. The Env spike is "opened" by binding to the first receptor on the target cell, CD4, resulting in the formation of a pre-hairpin intermediate (State 3). Binding to the second receptor, CCR5 or CXCR4, leads to the formation of a very stable gp41 six-helix bundle (State 4) and the fusion of viral and host cel membranes. Recent evidence has suggested the existence of multiple "relaxed intermediate states" (States 2a, 2b, etc.) between the unliganded closed Env conformation (State 1) and the pre-hairpin intermediate (State 3). HIV-1 strains differ in their propensity to make the transition from State 1 to the relaxed intermediate states; more triggerable or "reactive" Envs are more likely to sample the relaxed intermediate states. These differences in "Env reactivity" influence HIV-1 tropism and sensitivity to inhibition by small molecules and antibodies. Thus, defining the conformational landscape available to HIV-1 Env variants is essential for understanding HIV-1 biology and for guiding the development of interventions. The overall goal of this proposal is to understand the conformational transitions of the HIV-1 Envs that are critical to virus entry. Each of the three Specific Aims investigates a different stage of the HIV-1 entry process: 1) Specific Aim 1 tests the hypothesis that modification of specific structures on the Env trimer releases the restraints that maintain conformational State 1, allowing Env to sample the relaxed intermediate states (States 2a, 2b, etc.). The effects of the Env changes on HIV-1 dependence on target cell receptor levels and sensitivity to inhibition by small molecules and antibodies will be determined. 2) Specific Aim 2 uses gp41 cysteine-substitution mutants that are dependent upon a reducing agent for infectivity to test the hypothesis that the gp41 coiled coil in the pre-hairpin intermedite (State 3) forms in an ordered fashion. Conformations of Env targeted by gp41-directed entry inhibitors will be identified. 3) Specific Aim 3 will define the Env changes and mechanism underlying HIV-1 adaptation to replicate in CD4-positive cells expressing very low levels of the CCR5 coreceptor. The above studies will illuminate the dynamic conformational transitions of the HIV-1 Env membrane-fusing machine and will expedite the development of inhibitors of HIV-1 entry.

 描述（由申请人提供）：人类免疫缺陷病毒（HIV-1）包膜糖蛋白（Envs）介导病毒进入宿主细胞。包膜刺突是暴露在病毒表面的唯一病毒特异性成分，因此代表了小分子进入抑制剂和疫苗诱导抗体的关键靶标。 Env 刺突是由三个 gp120 外部 Env 和三个 gp41 跨膜 Env 组成的三聚体。为了逃避宿主中和抗体，未配体的 Env 尖峰呈现“闭合”构象（状态 1）。在病毒进入过程中，封闭的 Env 构象中存储的高势能被引导至病毒和靶细胞膜的最终融合中。 Env 刺突通过与靶细胞上的第一个受体 CD4 结合而“打开”，从而形成前发夹中间体（状态 3）。与第二个受体 CCR5 或 CXCR4 结合，导致形成非常稳定的 gp41 六螺旋束（状态 4）以及病毒和宿主细胞膜的融合。 最近的证据表明，在未配体的闭合Env构象（状态1）和发夹前中间体（状态3）之间存在多个“松弛中间状态”（状态2a、2b等）。 HIV-1 毒株的转变倾向不同 从状态1到宽松的中间状态；更具可触发性或“反应性”的环境更有可能对宽松的中间状态进行采样。 “Env 反应性”的这些差异影响 HIV-1 的向性以及对小分子和抗体抑制的敏感性。因此，定义 HIV-1 Env 变体可用的构象景观对于理解 HIV-1 生物学和指导干预措施的开发至关重要。 该提案的总体目标是了解对病毒进入至关重要的 HIV-1 包膜的构象转变。三个特定目标中的每一个都研究 HIV-1 进入过程的不同阶段：1) 特定目标 1 测试这样的假设：Env 三聚体上特定结构的修饰释放了维持构象状态 1 的限制，允许 Env 对松弛的中间状态（状态 2a、2b 等）进行采样。将确定 Env 变化对 HIV-1 对靶细胞受体水平的依赖性以及对小分子和抗体抑制的敏感性的影响。 2)具体目标2使用依赖于感染性还原剂的gp41半胱氨酸取代突变体来测试发夹前中间体(状态3)中的gp41卷曲螺旋以有序方式形成的假设。将鉴定 gp41 定向进入抑制剂靶向的 Env 构象。 3) 具体目标 3 将定义 HIV-1 适应在表达非常低水平的 CCR5 辅助受体的 CD4 阳性细胞中复制的环境变化和机制。 上述研究将阐明HIV-1 Env膜融合机的动态构象转变，并将加速HIV-1进入抑制剂的开发。