FMLF BINDING SITE ON FORMYL PEPTIDE RECEPTOR

中性粒细胞向入侵细菌的迁移部分依赖于 识别和结合细菌N-甲酰化肽的能力 (such作为fMLF。）在结合细菌肽后，N-甲酰基 肽受体（FPR）激活鸟苷酸结合蛋白（G 将信号转导至细胞内效应分子 引起一连串的细胞事件，包括趋化性、溶酶体 酶分泌和超氧化物的产生。除了正常的主机 除了防御功能外，中性粒细胞在慢性炎症中也起着核心作用。 炎症过程。通过调节中性粒细胞的行为， 超氧化物及其代谢物造成的组织损伤， 被阻止。了解甲酰肽的分子机制- 结合FPR，以及FPR-G蛋白的相互作用可能有助于 设计可用于控制慢性炎症的受体拮抗剂 炎症性疾病。总体目标是开发网站导向 光亲和扫描结合质谱分析作为一种 膜蛋白研究的通用工具。此外 将开发方法来阐明可能引起的结构变化， 通过使用噬菌体展示文库的位点特异性诱变， 光敏激动剂标记。我们提出了一个N的工作假设- 甲酰-Met-Leu-Phe（fMLF）与甲酰肽受体（FPR）的结合 基于所提出的G蛋白偶联受体的结构模型， 由Baldwin，已知的fMLF的3D结构结合到一个特定的 免疫球蛋白，以及视网膜和fMLF之间的结构相似性。我们 建议使用现场指导的方法来测试和完善这一工作假设 光亲和标记与定点诱变相结合。我们有 先前光亲和标记的甲酰肽受体（FPR）和 已经使用这种标记的受体来监测它与G- 蛋白质和肌动蛋白。目前的研究将大大扩展 通过制备更紧凑的光亲和性激动剂方法 类似物，其可用于绘制FPR的激动剂结合位点。我们 将使用各种各样的光亲和类似物，充分探测 激动剂位点并对光亲和交联位点进行测序， 受体跨膜组织的结构信息。 此外，使用定点突变，我们将确定那些 在激动剂结合和蛋白质折叠中重要的残基。 这 工作应提供有关FPR结构和 吞噬细胞趋化性的主要事件。它也应该作为一个 其他七螺旋受体的研究的概念框架。

The migration of neutrophils towards invading bacteria is partly dependent on their ability to recognize and bind bacterial N-formylated peptides (such as fMLF.) Upon binding of the bacterial peptide, the N-formyl peptide receptor (FPR) activates a guanyl nucleotide binding protein (G protein) which transduces the signal to intracellular effector molecules causing a cascade of cellular events including chemotaxis, lysosomal enzyme secretion and production of superoxide. In addition to normal host defense functions, neutrophils also play a central role in chronic inflammatory processes. By regulating the behavior of the neutrophils, much of the tissue damage caused by superoxide and its metabolites could be prevented. Understanding the molecular mechanism of formyl peptide- binding to FPR, as well as FPR-G protein interaction might facilitate the design of receptor antagonists that could be useful in controlling chronic inflammatory diseases. The broad goal is to develop site directed photoaffinity scanning in conjunction with mass spectral analysis as a generally applicable tool for studies of membrane proteins. In addition methods will be developed to elucidate possible structural changes caused by site specific mutagenesis using phage display libraries and affects of photoactive agonist labeling. We have developed a working hypothesis of N- formyl-Met-Leu-Phe (fMLF) binding to the formyl peptide receptor (FPR) based upon a structural model of G-protein coupled receptors as proposed by Baldwin, the known 3D structure of fMLF bound to a specific immunoglobulin, and the structural similarity between retinal and fMLF. We propose to test and refine this working hypothesis using site directed photoaffinity labeling in concert with site directed mutagenesis. We have previously photoaffinity labeled the formyl peptide receptor (FPR) and have used this labeled receptor to monitor its interaction with both G- protein and actin. The present studies will greatly extend the photoaffinity agonist approach by preparing more compact photoaffinity analogues which can be used to map the agonist binding site of FPR. We will use a wide variety of photoaffinity analogues that fully probe the agonist site and sequence the photoaffinity crosslinked sites to provide structural information on the transmembrane organization of the receptor. In addition, using site directed mutagenesis, we will determine those residues which are important in agonist binding and protein folding. This work should provide useful information about the structure of FPR and the primary events in the chemotaxis of phagocytes. It should also serve as a conceptual framework for the study of other heptahelical receptors.