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

项目摘要/摘要-项目2 HIV-1膜蛋白(Env)与B细胞表面抗原受体(BCR)相互作用启动B细胞的结构分析 信号和激活是理解针对HIV蛋白免疫原的抗体反应的关键。近期 对细胞膜上BCR复合体组织的研究支持BCR存在于 需要在结构术语中定义的不同信令状态。我们假设了以下不同的状态 BCR复合体--1)“信令抑制”，2)“信令功能”和3)“信令中断”。最新进展 HIV-1环境设计，包括针对生殖系前体的设计，导致了环境的发展 免疫原作为艾滋病毒疫苗的潜在候选者。不同特性和信令状态的BCR如何 与Env蛋白免疫原相互作用，触发信号并激活这些细胞，目前还不清楚。 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)、非正规性糖链结合bNAbs和拟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/生化、结构和免疫学分析，以确定 HIV env-bcr相互作用激活表达bNab或生殖系前体bcr的B细胞的特性。在……里面 目标1，我们将进行冷冻-EM和分子动力学模拟分析来确定抗原的结构- 具有自身或广泛中和HIV-1抗体特异性的配基BCR复合体。此外，我们 将用呈现非规范Fab的糖链结合bNAbs的特异性来定义BCR的结构 配置(I型与Y型)。在目标2中，我们将研究受干扰的bNab前体的特异性 近端信号转导，并确定这种BCR是否显示出与Env明显的细胞表面相互作用动力学 蛋白质。AIM 3的研究将确定抗原-BCR相互作用参数，以增强B细胞信号转导，抗原 包膜蛋白表位的内化和MHC类II-肽递呈。拟议的研究将架起桥梁 高分辨结构和抗原-bcr相互作用动力学对B细胞信号和激活的影响。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，并指导制定提高疫苗效力的战略。

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.