Project 2 - B cell antigen receptor structure and antigen-BCR interaction dynamics

项目概要/摘要-项目2 HIV-1 Env与B细胞抗原受体相互作用启动B细胞的结构分析 信号传导和激活是理解针对HIV蛋白免疫原的抗体应答的关键。最近 对BCR复合物在细胞膜上的组织结构的研究支持了BCR存在于细胞膜上的模型。 不同的信号状态，需要在结构方面的定义。我们假设以下不同的状态 BCR复合物的- 1）“信号抑制”，2）信号活性和3）“信号破坏”。进展 HIV-1 Env的设计，包括那些针对生殖系前体的设计，导致了Env的发展。 作为HIV疫苗的潜在候选者。具有不同特异性和信号状态的BCR 与Env蛋白相互作用触发信号传导并激活这些细胞的免疫原尚不清楚。 该项目的总体目标是确定具有广泛中和特异性的BCR-抗原结构 抗体（bnAb）、非典型聚糖结合bnAb和待分离的自体中和抗体 （anAb）。在这个项目中，我们将进行生物物理/生物化学，结构和免疫学分析，以确定 HIV Env-BCR相互作用用于活化表达bnAb或生殖系前体BCR的B细胞的特性。在 目的1，我们将进行冷冻电镜和分子动力学模拟分析，以确定抗原的结构， 具有自体或广泛中和HIV-1抗体特异性的配体BCR复合物。另外我们 将定义具有聚糖结合bnAb特异性的BCR的结构， 配置（I形与Y形）。在目标2中，我们将研究bnAb前体的特异性， 近端信号传导，并确定这些BCR是否显示出与Env不同的细胞表面相互作用动力学 proteins.目标3中的研究将定义增强B细胞信号传导的抗原-BCR相互作用参数， Env蛋白表位的内化和MHC II类肽呈递。拟议的研究将连接 高分辨率结构和抗原-BCR相互作用动力学对B细胞信号传导和活化的影响。很长的- 这些研究的范围目标是为理解体液反应提供机制基础， 艾滋病毒-1疫苗和指导战略的制定，以提高疫苗的效力。

Project Summary/Abstract – Project 2 Structural analysis of how HIV-1 Envelope (Env) interacts with antigen receptor on B cells (BCR) to initiate B cell signaling and activation is key to understanding antibody responses against HIV protein immunogens. Recent studies of the organization of the BCR complex on the cell membrane supports a model in which BCRs exist in different signaling states that require definition in structural terms. We hypothesize the following distinct states of the BCR complex – 1) “signaling-inhibited’, 2) signaling-competent and 3) ‘signaling-disrupted’. Advances in HIV-1 Env design including those that target germline precursors have led to the development of Env immunogens as potential candidates for HIV vaccines. How BCRs of distinct specificities and signaling-states interact with Env protein immunogens that trigger signaling and activate these cells are not clearly understood. The overall goal of the project is to define BCR-antigen structures with specificity of broadly neutralizing antibodies (bnAb), non-canonical glycan-binding bnAbs and to-be isolated autologous neutralizing antibodies (anAb). In this project, we will perform biophysical/biochemical, structural and immunological analyses to define properties of HIV Env-BCR interactions for activation of B cells expressing bnAb or germline precursor BCRs. In Aim 1, we will perform Cryo-EM and molecular dynamic simulation analyses to define structures of antigen- liganded BCR complex with specificities of autologous or broadly neutralizing HIV-1 antibodies. In addition, we will define the structures of BCRs with specificities of glycan-binding bnAbs that present non-canonical Fab configurations (I-shaped versus Y-shaped). In Aim 2, we will study specificity of bnAb precursors with disrupted proximal signaling and determine whether such BCRs show distinct cell surface interaction dynamics with Env proteins. Studies in Aim 3 will define antigen-BCR interaction parameters that enhance B cell signaling, antigen internalization and MHC class II-peptide presentation of Env protein eptiopes. The proposed studies will bridge high-resolution structures and antigen-BCR interaction dynamics to B cell signaling and activation. The long- range goals of these studies are to provide the mechanistic basis for understanding the humoral response to HIV-1 vaccines and guide development of strategies to enhance vaccine efficacy.