Inhibition of the Classical & Lectin Complement Pathways by Staphylococcus aureus Eap

古典的抑制

基本信息

批准号：
8891551
负责人：
Brian V Geisbrecht
金额：
$ 18.75万
依托单位：
KANSAS STATE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2015
资助国家：
美国
起止时间：
2015-01-01 至 2016-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8891551
关键词：
Active Sites Acute Adherence Affinity Anti-Inflammatory Agents Anti-inflammatory Autoimmune Diseases Bacteria Basic Science Binding Binding Sites Biochemical Biological Assay Cell surface Chronic Complement Complement 3 Convertase Complement 3b Complement 4b Complement Activation Complement Inactivators Complex Cyclic Peptides Development Disease Dose Enzymes Event Extracellular Domain Extracellular Protein FDA approved Foundations Future Generations Goals Graft Rejection Human Human body Hyperactive behavior Immunity Inflammation Inflammation Mediators Inflammatory Intervention Investigation Lead Lectin Libraries Malignant Neoplasms Mediating Modeling Molecular Mutagenesis Nature Neurodegenerative Disorders Pathway interactions Peptide Hydrolases Peptides Phage Display Pharmaceutical Preparations Play Price Process Protein Binding Protein Family Protein Inhibition Proteins Rare Diseases Regulation Reperfusion Injury Role Route Sepsis Syndrome Series Serine Protease Serpins Site Specificity Staphylococcus aureus Structure Structure-Activity Relationship System Therapeutic Virulent Whole Blood Work alternative pathway complement C3 convertase base biomaterial incompatibility complement 4b-binding protein complement C2a complement C3 precursor complement C4c complement pathway complement system design driving force extracellular human disease inhibitor/antagonist insight member neutrophil novel novel strategies pathogen protein structure function public health relevance response screening therapeutic target

项目摘要

DESCRIPTION (provided by applicant): Over the last several years, our understanding of the complement evasion mechanisms utilized by pathogens has increased precipitously through the study of the virulent bacterium Staphylococcus aureus. By screening a library of secreted S. aureus proteins in a human whole-blood model of inflammation, we have identified the Extracellular Adherence Protein (Eap) as the first known S. aureus inhibitor of the Classical (CP) and Lectin (LP) pathways of complement. Eap inhibits both of these pathways in a dose-dependent manner that requires formation of high-nanomolar affinity interaction with complement component C4b. This interaction blocks formation of the CP/LP pro-C3 convertase complex (C4b/C2), which dramatically lowers levels of the active CP/LP C3 convertase (C4b/C2a). Using the same whole-blood model, we have also identified Eap as a potent inhibitor of Neutrophil Serine Proteases (NSPs). Unlike conventional serpins, Eap inhibition of NSPs is non-covalent in nature. Furthermore, it occurs through a molecular mechanism distinct from its effects on the complement system since two related proteins, EapH1 and EapH2, also block NSP activity but have no effect on complement. In this proposal, we will investigate the molecular basis for the specificity of Eap's effects on the CP/LP through two Specific Aims: (1) We will characterize the biochemical and structural basis for Eap binding to complement protein C4b, and (2) We will characterize peptides that compete with Eap for C4b binding and determine whether they retain Eap-like inhibitory activities against the CP/LP. We expect that this integrated structure/function and discovery approach will provide new insight into regulation of the CP/LP. In turn, this may hold important clues into the design and optimization of novel complement-targeted, anti-inflammatory therapeutics in the future.

描述（由申请人提供）：在过去的几年中，通过对有毒细菌金黄色葡萄球菌的研究，通过筛选人体中的分泌金黄色葡萄球菌蛋白库，我们对病原体利用的补体逃避机制的了解急剧增加。 -炎症的血液模型，我们已确定细胞外粘附蛋白 (Eap) 是第一个已知的经典 (CP) 和凝集素的金黄色葡萄球菌抑制剂Eap 以剂量依赖性方式抑制这两种途径，需要与补体成分 C4b 形成高纳摩尔亲和力相互作用，这种相互作用会阻止 CP/LP pro-C3 转化酶复合物 (C4b/) 的形成。 C2)，它显着降低活性 CP/LP C3 转化酶 (C4b/C2a) 的水平。使用相同的全血模型，我们还发现 Eap 是中性粒细胞丝氨酸的有效抑制剂。与传统的丝氨酸蛋白酶抑制剂 (NSP) 不同，Eap 对 NSP 的抑制本质上是非共价的，而且它通过与其对补体系统的作用不同的分子机制发生，因为两种相关蛋白 EaPH1 和 EaPH2 也会阻断 NSP 活性。在本提案中，我们将通过两个具体目标研究 Eap 对 CP/LP 影响的特异性的分子基础：(1) 我们将表征其生化和补体。 (2) 我们将表征与 Eap 竞争 C4b 结合的肽，并确定它们是否保留针对 CP/LP 的 Eap 样抑制活性。发现方法将为 CP/LP 的调节提供新的见解，这可能为未来新型补体靶向抗炎疗法的设计和优化提供重要线索。