Defining the mechanism of lipid peroxidation in controlling Staphylococcus aureus infections

定义脂质过氧化控制金黄色葡萄球菌感染的机制

• 批准号: 10703348
• 负责人: William Norris Beavers
• 金额: $ 10.73万
• 依托单位: LOUISIANA STATE UNIV A&M COL BATON ROUGE
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-12 至 2024-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10703348
• 关键词: Affinity; Amino Acids; Antibiotics; Arachidonic Acids; Automobile Driving; Bacteria; Biology; Biotin; Cell physiology; Cells; Cessation of life; Chemicals; Chemistry; Development; Drug resistance; Enzymes; Excretory function; Fatty Acids; Future; Harvest; Human; Immune; In Vitro; Infection; Invaded; Ions; Kinetics; Knowledge; Lipid Peroxidation; Lipids; Measures; Modification; Molecular; Mus; Mutate; Oxidants; Oxidative Stress; Pathogenesis; Pathway interactions; Pharmaceutical Preparations; Phospholipids; Polyunsaturated Fatty Acids; Post-Translational Protein Processing; Process; Proteins; Proteome; Reaction; Recombinants; Respiration; Role; Scanning; Sepsis; Staphylococcus aureus; Staphylococcus aureus infection; Systemic infection; Testing; Therapeutic; Therapeutic Intervention; Tissues; Toxic effect; United States; Validation; antimicrobial; bactericide; design; experimental study; in vivo; in vivo evaluation; insight; ketoaldehyde; macromolecule; mouse model; mutant; novel; novel therapeutics; pathogen; resistant strain; small molecule; targeted treatment; therapeutic development; tool

Project Summary Staphylococcus aureus infects every niche of the human host and is the leading cause of Gram-positive sepsis. There are over 900,000 severe S. aureus infections in the United States annually, emphasizing the need for new antibiotics to treat these infections. Understanding the molecular mechanisms used by the host to kill S. aureus and by S. aureus to defend against host killing will identify and validate novel targets for antimicrobial design. When the host encounters S. aureus, immune cells excrete various bactericidal small molecules. One class of bactericidal small molecules are polyunsaturated fatty acids, which are toxic to many bacterial species, but until recently the mechanism of toxicity was undefined. We discovered that arachidonic acid (AA), an abundant host polyunsaturated fatty acid, is bactericidal against S. aureus through a lipid peroxidation mechanism. AA is oxidized in S. aureus to a,b-unsaturated carbonyls and g-ketoaldehydes that are electrophilic, reacting with nucleophilic amino acids of the S. aureus proteome. Scavenging either oxidants that initiate lipid peroxidation or electrophiles generated through lipid peroxidation protects S. aureus from AA killing, confirming lipid peroxidation generated electrophiles as the bactericidal effectors of AA. Discovering the mechanism of AA toxicity against S. aureus is just the first step in identifying and validating lipid peroxidation as an antimicrobial strategy. We do not know the lipid electrophile species generated in S. aureus and what S. aureus proteins are targeted by electrophiles. We also do not know the S. aureus processes that produce the oxidants responsible for initiating lipid peroxidation or the identity of the oxidants produced in S. aureus. Finally, we do not know the specific host niches where lipid peroxidation is bactericidal or which host niches are most promising to test lipid peroxidation as an antimicrobial therapy. This proposal will expand the understanding of the bactericidal mechanisms of AA both in vitro and in vivo by testing three main hypotheses. In Aim 1, we will determine the lipid electrophile species and pathways of formation in S. aureus. This aim will test the hypothesis that oxidants derived from S. aureus respiration initiate lipid peroxidation resulting in a diverse array of bactericidal lipid electrophiles. In Aim 2, we will discover the protein targets of AA-derived lipid electrophiles in S. aureus. This aim will test the hypothesis that lipid electrophiles exert toxicity by disrupting enzymes in essential S. aureus processes through post-translational modification. In Aim 3, we will define the role of AA release in S. aureus pathogenesis. This aim will test the hypothesis that inhibiting host AA release results in increased S. aureus pathogenesis in a murine model of systemic infection and that the bactericidal role of AA will be different across the multiple host tissues tested. The insights gained from this proposal will further validate lipid peroxidation as an antimicrobial therapy, identify S. aureus proteins to target for antimicrobial development, and expand the understanding of the bactericidal role of AA in vivo.

项目摘要 金黄色葡萄球菌感染人类宿主的每一个生态位，是革兰氏阳性菌的主要原因。 败血症有超过900，000个严重的S。金黄色葡萄球菌感染在美国每年，强调 需要新的抗生素来治疗这些感染。了解宿主使用的分子机制， 杀死S。aureus和S.金黄色葡萄球菌防御宿主杀伤将确定和验证新的目标， 抗菌设计当宿主遇到S.金黄色葡萄球菌，免疫细胞分泌各种杀菌小 分子。一类杀菌小分子是多不饱和脂肪酸，它对许多人来说是有毒的。 细菌种类，但直到最近的毒性机制是不确定的。我们发现花生四烯酸 酸（AA）是一种丰富的宿主多不饱和脂肪酸，对沙门氏菌具有杀菌作用。金黄色葡萄球菌通过脂质 过氧化机理AA在S中被氧化。金黄色葡萄球菌转化为A，B-不饱和羰基和G-酮醛， 是亲电子的，与S.金黄色葡萄球菌蛋白质组清除氧化剂 启动脂质过氧化或通过脂质过氧化产生的亲电体保护S。来自AA的金黄色葡萄球菌 杀，证实脂质过氧化产生的亲电体是AA的杀菌效应物。发现所述 AA对S.金黄色葡萄球菌只是识别和验证脂质过氧化作用的第一步 作为一种抗菌策略。我们不知道在S. aureus和S. 金黄色葡萄球菌蛋白被亲电试剂靶向。我们也不知道S。aureus过程产生 负责启动脂质过氧化反应的氧化剂或S.金黄色。 最后，我们不知道脂质过氧化作用是杀菌作用的特定宿主生态位，也不知道哪些宿主生态位 是最有希望测试脂质过氧化作为一种抗菌治疗。这项建议将扩大 通过测试三个主要假设，了解AA在体外和体内的杀菌机制。 目的1：确定S.金黄色。这一目标将 验证氧化剂来源于S.金黄色葡萄球菌呼吸启动脂质过氧化， 各种各样的杀菌脂质亲电体。目的二是寻找AA衍生脂质的靶蛋白 S.金黄色。这一目的将检验脂质亲电体通过破坏细胞内蛋白质而产生毒性的假设。 必需S.金黄色葡萄球菌通过翻译后修饰进行加工。在目标3中，我们将定义 AA释放在S.金黄色葡萄球菌发病机制这一目的将检验抑制宿主AA释放 增加了S。金黄色葡萄球菌在小鼠全身感染模型中的发病机制， AA的作用在测试的多种宿主组织中将是不同的。从该提案中获得的见解将 进一步验证脂质过氧化作为抗微生物疗法，鉴定S.目标蛋白 抗微生物的发展，并扩大了对AA在体内杀菌作用的理解。