Staphylocidal Mechanism of Platelet Microbicidal Protein

血小板杀菌蛋白的杀菌机制

• 批准号: 6433788
• 负责人: ARNOLD S BAYER
• 金额: $ 31.76万
• 依托单位: LUNDQUIST INSTITUTE FOR BIOMEDICAL INNOVATION AT HARBOR-UCLA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-12-01 至 2006-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6433788
• 关键词: Staphylococcus aureus; Staphylococcus infection; antibacterial agents; antibacterial antibody; bacteria infection mechanism; bacterial antigens; bacterial cytopathogenic effect; bacterial proteins; bactericidal immunity; gene mutation; host organism interaction; intracellular; microorganism culture; microorganism immunology; platelets; proteomics; site directed mutagenesis; transfection /expression vector; transposon /insertion element

DESCRIPTION (provided by the applicant): Staphylococcus aureus is a virulent pathogen which is associated with a broad-spectrum of clinical infections. Its ability to colonize host tissues, and to persist and proliferate within host tissues requires the organism to circumvent innate host defense mechanisms. We have discovered that mammalian platelets store and secrete a family of antimicrobial peptides at potential sites of endovascular damage and microbial colonization that serve to both growth inhibit and kill S. aureus. In the previous grant period, we have delineated that the principal antimicrobial peptide which is secreted from platelets (thrombin-induced platelet microbicidal protein-1 [tPMP-1]), interacts with S. aureus in vitro by initial attachment to the cytoplasmic membrane, after which a microbicidal cascade is triggered in strains intrinsically susceptible to this peptide. In contrast, those strains which were engineered to be resistant to tPMP-1 in vitro (e.g., by transposon mutagenesis) do so by changing the basic biology of their cytoplasmic membrane target for tPMP-1. In vitro susceptibility to tPMP-1 is mirrored by enhanced clearance of such strains in animal models of endovascular infection; in contrast, in vitro resistance to tPMP-1 is correlated with an augmented survival advantage in the same animal models. The overall purposes of this proposal are: i) to define the mechanisms by which tPMP-1 executes its microbicidal effects, particularly focusing on intracellular targeting and activation of stress response systems; and ii) to delineate the mechanisms, genetic pathways and membrane biochemical adaptations by which the organism is able to successfully respond to exposures to tPMP-1 for survival. For these purposes, we will utilize a series of well-characterized and isogenic strain pairs of S. aureus (including site-directed plasmid mutants, as well as mutants with plasmid reporter fusions) that will enable us to define both the mechanisms of microbicidal action of tPMP-1, as well as the homeostatic adaptive pathways used by the organism to survive tPMP-1 exposures. Moreover, we will employ proteomics approaches to divulge novel genes and metabolic pathways triggered by tPMP-1 as part of either its microbicidal cascade, or as part of the organism's adaptive strategies. These studies will provide a solid foundation for the future design of unique platelet peptide congeners which are better able to target S. aureus strains for killing, as well as to circumvent innate homeostatic mechanisms used by the organism for survival.

描述(申请人提供)：金黄色葡萄球菌是一种致命的 与广泛的临床感染有关的病原体。它的 能够在宿主组织中定植，并在宿主内持续和增殖 组织需要有机体绕过固有的宿主防御机制。我们 已经发现哺乳动物的血小板储存和分泌一系列 血管内损伤潜在部位的抗菌肽与微生物 既能抑制生长又能杀死金黄色葡萄球菌的殖民活动。在 在之前的授权期内，我们已经划定了主要的抗菌剂 由血小板(凝血酶诱导的血小板)分泌的多肽 杀微生物蛋白-1[TPMP-1])与金黄色葡萄球菌体外相互作用 附着在细胞膜上，之后一个杀微生物级联反应 在对这种多肽具有内在易感性的菌株中触发。相比之下， 那些在体外被设计成对TPMP-1具有抗药性的菌株(例如， 通过转座子突变)通过改变它们的基本生物学来做到这一点 针对TPMP-1的细胞膜靶点。对TPMP-1的体外敏感性为 在血管内动物模型中这些菌株的清除增强也是一种反映 相反，在体外对TPMP-1的耐药性与 在相同的动物模型中增强了生存优势。的总体目的 这项建议是：i)界定最终淘汰管理计划-1执行其 杀灭微生物的作用，特别是关注细胞内靶向和 激活应激反应系统；以及ii)描述机制， 有机体的遗传途径和膜生化适应 能够成功应对TPMP-1的暴露以求生存。为了这些 目的，我们将利用一系列特性良好的等基因菌株 两对金黄色葡萄球菌(包括定点质粒突变体和突变体 与质粒报告融合)，这将使我们能够定义 TPMP-1的杀菌作用机制及内环境平衡 有机体用来在TPMP-1暴露下生存的适应性途径。此外， 我们将使用蛋白质组学方法来揭示新的基因和新陈代谢 TPMP-1作为其杀微生物级联反应的一部分或作为 这是生物体适应策略的一部分。这些研究将提供一个坚实的 为未来设计独特的血小板多肽同系物奠定基础 能够更好地针对金黄色葡萄球菌菌株进行杀戮，以及规避 生物体为生存而使用的先天内环境平衡机制。