Structural and Functional Studies on the Platelet Adherence Protein A of Streptoc

链球菌血小板粘附蛋白A的结构和功能研究

• 批准号: 8912358
• 负责人: Champion Christdoss Selvakumar Deivanayagam
• 金额: $ 18.38万
• 依托单位: UNIVERSITY OF ALABAMA AT BIRMINGHAM
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-08-15 至 2018-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8912358
• 关键词: Address; Adherence; Adhesions; Affect; American Heart Association; Antibiotic Therapy; Antibiotics; Bacteria; Bacterial Adhesion; Binding; Binding Sites; Blood; Blood Platelets; Cell Wall; Cessation of life; Communicable Diseases; Complex; Congenital Heart Defects; Crystallization; Cytoplasmic Granules; Dental Care; Development; Disease; Disease Progression; Docking; Genes; Guidelines; Health; Heart Valves; Homologous Protein; Human; Immune system; Immunoglobulin G; Individual; Infective endocarditis; Integrins; Lead; Life; Maps; Mediating; Membrane Proteins; Methodology; Modeling; Molecular; Molecular Weight; Morbidity - disease rate; N-terminal; Patients; Penetration; Peptide Signal Sequences; Peptidoglycan; Platelet Activation; Play; Process; Proteins; Published Comment; Reaction; Recruitment Activity; Resolution; Rest; Role; Sialic Acids; Signal Transduction; Site-Directed Mutagenesis; Staphylococcus aureus; Stream; Streptococcus; Streptococcus gordonii; Streptococcus mitis; Streptococcus mutans; Streptococcus oralis; Structure; Surface; Therapeutic; Thrombus; VWF gene; design; inhibitor/antagonist; member; microbial; mortality; mutant; novel; oral streptococci; pathogen; prevent; receptor; therapeutic development

DESCRIPTION (provided by applicant): Infective endocarditis (IE) is a life-threatening infectious disease that is associated with morbidity and mortality, and affects individuals who are pre-disposed to cardiac defects. It is thought that transient bacteria gain access through dental procedures as well as through other modes to the blood stream and reach the heart valves and colonize, resulting in life threatening IE. Even with aggressive antibiotic treatment 36% of the patients succumb to the disease, resulting in death. In IE, the camouflage provided by the thrombus formation provides a safe haven from the host immune system for the bacteria to grow within the accumulated platelets. In addition, the poor penetration of antibiotics compounds the difficulties in treating IE patients. Therefore, to treat IE patients the need exists to develop other methodologies to intervene and impede bacterial attachment to platelets. As the primary adherence of bacteria to platelets begins with microbial surface proteins, they are considered to play a vital role in IE disease progression. It is here that the elucidation of the structures of bacterial surface proteins involved in platelet adhesion, as well as the structure of its co-complex with the human receptor would begin to unravel the mysteries behind this interaction. This characterization could lead to the development of inhibitors that prevent bacterial attachment and subsequent platelet activation, and open an avenue for the development of therapeutics to treat IE patients. In this resubmission application we present progress and propose to study one of the surface proteins, PadA on Streptococcus gordonii that interacts with platelets. PadA plays an important role in adhesion, and its interaction through RGD-like motif with the platelet integrin GpIIbIIIa instigates outside-in signaling, that results i platelet spreading and granule release. Apart from PadA, two other homologous proteins Hsa and GspB (from DL1 and Challis strains) also interact with platelets through the GPIba integrin, and are believed to mediate platelet rolling. Our long range hypothesis is that "Streptococcus gordonii's surface proteins (GspB, HsA and PadA) synergistically interact with platelets in a novel manner that results in both the inside-out and outside-in signaling resulting in activation and spreading of platelets". To begin to address this long range hypothesis, in this proposal we focus on PadA, and set out to structurally characterize the N-terminal platelet adherence region as well as narrow down the region of interaction within the platelet integrin GpIIbIIIa through two specific aims. Aim 1: Determine the structure of PadA's N-terminal platelet adherence region; Aim 2: Narrow down the region of PadA's adherence on GpIIbIIIa. The structure of PadA and its interaction with platelet integrin GpIIbIIIa, would represent a major step in the direction towards understanding bacterial-platelet interaction, and could serve as a model for other bacterial surface protein interactions with platelets.

描述（由申请方提供）：感染性心内膜炎（IE）是一种与发病率和死亡率相关的危及生命的感染性疾病，影响易患心脏缺陷的个体。据认为，瞬时细菌通过牙科手术以及通过其他模式进入血流，到达心脏瓣膜并定植，导致危及生命的IE。即使使用积极的抗生素治疗，36%的患者也会死于该病，导致死亡。在IE中，血栓形成提供的伪装为细菌在积聚的血小板内生长提供了远离宿主免疫系统的安全港。此外，抗生素的渗透性差也增加了IE患者的治疗难度.因此，治疗IE患者需要 开发其他方法来干预和阻止细菌附着在血小板上。由于细菌对血小板的主要粘附始于微生物表面蛋白，因此它们被认为在IE疾病进展中起着至关重要的作用。正是在这里，阐明了与血小板粘附有关的细菌表面蛋白的结构，以及 它与人类受体的共复合物将开始揭开这种相互作用背后的奥秘。这种特征可能会导致抑制剂的开发，以防止细菌附着和随后的血小板活化，并为治疗IE患者的治疗方法的开发开辟一条途径。 在这个重新提交的申请，我们目前的进展，并建议研究的表面蛋白之一，PadA的戈登链球菌与血小板相互作用。PadA在粘附中起重要作用，其通过与血小板整合素GpIIbIIIa的RGD样基序相互作用引发由外向内信号传导，导致血小板铺展和颗粒释放。除了PadA，另外两种同源蛋白Hsa和GspB（来自DL 1和查利斯菌株）也通过GPIba整联蛋白与血小板相互作用，并且被认为介导血小板滚动。我们的长期假设是“戈登链球菌的表面蛋白（GspB，HsA和PadA）以一种新的方式与血小板协同相互作用，导致由内而外和由外而内的信号传导，导致血小板的活化和扩散”。为了开始解决这个长范围假说，在这个提议中，我们集中于PadA，并着手从结构上表征N-末端血小板粘附区域，以及通过两个途径缩小血小板整合素GP IIb IIIa内的相互作用区域。 具体目标。目的1：确定PadA N端血小板粘附区的结构;目的2：缩小PadA在GpIIbIIIa上的粘附区域。 PadA的结构及其与血小板整合素GpIIbIIIa的相互作用，将代表朝着理解细菌-血小板相互作用的方向迈出的重要一步，并可作为其他细菌表面蛋白与血小板相互作用的模型。