Structural Basis of chemokine CXCL1 recognition with CXCR2 receptor

趋化因子CXCL1及其受体CXCR2是一种A类G蛋白偶联受体。 在将血液中性粒细胞引导到感染和损伤部位方面起着至关重要的作用。CXCR2基因的异常调节 激活会导致宿主组织损伤和疾病。CXCL1在两个不同的位点与CXCR2结合：N- 末端结构域(位点-I，趋化因子特有)和由细胞外受体定义的沟槽 环/跨膜螺旋(位点-II，与所有A类受体共享)。分子基础是通过 哪种趋化因子结合两个不同的位点决定了CXCR2的激活尚不清楚。结构和 序列分析表明，介导结合的趋化因子和受体残基是 非结构化的或构象动态的。我们认为CXCL1结合在CXCR2的I位， 最初的强制性步骤，触发对Site-II至关重要的结构和动态变化 互动。我们将使用一种结合核磁的混合策略来验证我们的假设 核磁共振波谱和分子动力学(MD)模拟。我们将确定 CXCL1-CXCR2N-末端的构象动力学作用 使用核磁共振光谱学的结构域复合体(目标1)。我们将生成CXCL1的结构模型 通过合并I位核磁共振结构与N-末端结构域的CXCR2结合，并在此之前 确定了CXCR2的结构，并使用扩展的MD模拟来描述CXCL1如何在 位点-I在位点-II与受体结合(目标2)。我们将描述CXCL1站点I和站点II如何 从AIMS 1和AIMS 2鉴定的残基通过细胞分析介导CXCR2的激活(AIMS 3)。这些 研究将为CXCR2激活和激活的分子机制提供关键的见解 将推进干扰CXCR2激活和缓解疾病的治疗方法的设计。

Chemokine CXCL1, and its receptor CXCR2, a class-A G protein-coupled receptor (GPCR), play a crucial role in directing blood neutrophils to sites of infection and injury. A dysregulation in CXCR2 activation results in host tissue damage and disease. CXCL1 binds CXCR2 at two distinct sites: N- terminal domain (Site-I, unique to chemokines) and a groove defined by the receptor extracellular loops/transmembrane helices (Site-II, shared with all class A receptors). The molecular basis by which chemokine binding two distinct sites determine CXCR2 activation is not known. Structures and sequence analyses reveal that chemokine and receptor residues that mediate binding are either unstructured or conformationally dynamic. We propose that CXCL1 binding at Site-I of CXCR2, the initial obligatory step, triggers structural and dynamic changes that are essential for Site-II interactions. We will test our hypothesis using a hybrid strategy that combines nuclear magnetic resonance (NMR) spectroscopy and molecular dynamics (MD) simulations. We will determine the structure and characterize the role of conformational dynamics of Site-I CXCL1-CXCR2 N-terminal domain complex using NMR spectroscopy (Aim 1). We will generate a structural model of CXCL1 bound to CXCR2 at the N-terminal domain by merging Site-I NMR structure and previously determined CXCR2 structure, and use extended MD simulations to describe how CXCL1 bound at Site-I engages the receptor at Site-II (Aim 2). We will characterize how CXCL1 Site-I and Site-II residues identified from Aims 1 and 2 mediate CXCR2 activation using cellular assays (Aim 3). These studies will provide critical insights into the molecular mechanisms underlying CXCR2 activation and will advance designing therapeutics that disrupt CXCR2 activation and alleviate disease.