Characterization of molecular mechanisms of resistance to antimicrobial fatty acids in the staphylococci

葡萄球菌抗微生物脂肪酸分子机制的表征

• 批准号: RGPIN-2016-05047
• 负责人: Heinrichs, David
• 金额: $ 4.66万
• 依托单位: University of Western Ontario
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=653371
• 关键词: Characterization; molecular; mechanisms; resistance; antimicrobial

Background***Approximately 25% of humans are persistently colonized by S. aureus. Preferred sites of colonization of humans are the anterior nares, axillae, perineum, hands, chest and limbs, while in cattle it is the teat skin. Accordingly, its ability to persist on skin is an important mediator of transmission in both humans and animals. Yet, to persist on skin, S. aureus must resist innate defense barriers of the skin including long-chain unsaturated free fatty acids (uFFAs) which possess antimicrobial activity. uFFAs such as sapienic acid, palmitoleic acid, linoleic acid and arachidonic acid inhibit the growth of S. aureus. Indeed, these microbicidal fatty acids are part of the first line of defense against colonization by microbes. Sapienic acid is released from triglycerides secreted by the sebaceous glands in the skin and its secretion is defective in individuals with atopic dermatitis, resulting in increased carriage of S. aureus and increased susceptibility to infection by S. aureus. Nasal secretions also contain linoleic, arachidonic and palmitoleic acids, while staphylococcal abscesses contain abundant quantities of linoleic acid. S. aureus is an effective colonizer of the skin and nose, despite exposure to antimicrobial fatty acids******Hypotheses***We hypothesize that S. aureus has evolved, or can evolve, mechanisms of resistance to microbicidal fatty acids. We further hypothesize that identification of resistance mechanisms will shed significant insight into the biological targets of uFFAs. ******Progress***My laboratory has identified a heretofore unknown resistance mechanism against uFFAs, involving single nucleotide polymorphisms in RNaseY, a membrane of the RNA degradasome. ******Aims***Elucidating the link between RNaseY SNPs and resistance to fatty acids are the overarching aims of this research program. ***Aim 1: Define the fatty acid resistance mechanism in strains containing RNaseY polymorphisms. Using several parallel lines of investigation, this aim will characterize the RNaseY-dependent mechanism of resistance to fatty acids.***Aim 2: Functional characterization of RNaseY variants. This aim will characterize SNP-associated, gain-of-function changes in known functions of RNaseY. ***Aim 3: Define the link between SNPs and elevated resistance to fatty acids. Amino acid changes in RNaseY will be characterized in detail for their ability to confer increased resistance to fatty acids.***Aim 4: Identification and characterization of S. aureus variants resistant to additional fatty acid structures. This will yield valuable information on fatty acid-structure specific mechanisms of action of fatty acids on the S. aureus cell.******Significance***This discovery-based research program will address important and unique questions concerning physiological responses of S. aureus to microbicidal fatty acids, and the ability of S. aureus to evolve resistance to these compounds.

背景 * 大约25%的人类持续被S.金黄色。人的优选定殖部位是前鼻孔、腋窝、会阴、手、胸部和四肢，而牛的优选定殖部位是乳头皮肤。因此，其在皮肤上持续存在的能力是人类和动物中传播的重要媒介。然而，要在皮肤上坚持，S。金黄色葡萄球菌必须抵抗皮肤的先天防御屏障，包括具有抗微生物活性的长链不饱和游离脂肪酸（uFFA）。uFFA如十六碳烯酸、棕榈油酸、亚油酸和花生四烯酸抑制S.金黄色。事实上，这些杀微生物脂肪酸是抵抗微生物定植的第一道防线的一部分。Sapienic acid是从皮肤中皮脂腺分泌的甘油三酯中释放出来的，在特应性皮炎患者中，Sapienic acid的分泌是有缺陷的，导致S。金黄色葡萄球菌感染的敏感性增加。金黄色。鼻分泌物还含有亚油酸、花生四烯酸和棕榈油酸，而葡萄球菌分泌物含有大量的亚油酸。S.金黄色葡萄球菌是皮肤和鼻子的有效定植者，尽管暴露于抗微生物脂肪酸 * 假设 * 我们假设S.金黄色葡萄球菌已经进化出或可以进化出对杀微生物脂肪酸的抗性机制。我们进一步假设，耐药机制的鉴定将对uFFA的生物学靶点有重要的了解。** 进展 * 我的实验室已经确定了一种迄今为止未知的针对uFFA的抗性机制，涉及RNA酶Y（RNA降解酶体的膜）中的单核苷酸多态性。** 目的 * 阐明RNaseY SNP与脂肪酸抗性之间的联系是本研究计划的首要目标。* 目的1：定义含有RNaseY多态性的菌株中的脂肪酸抗性机制。使用几条平行的研究路线，这一目标将表征RNaseY依赖的脂肪酸抗性机制。目的2：RNaseY变体的功能表征。该目标将表征RNaseY已知功能中SNP相关的功能获得性变化。* 目标3：确定SNP与脂肪酸抗性升高之间的联系。RNaseY中的氨基酸变化将详细表征其赋予增加的脂肪酸抗性的能力。*目的4：S.金黄色葡萄球菌变体对额外的脂肪酸结构具有抗性。这将产生有价值的信息的脂肪酸结构的具体机制的脂肪酸对S。金黄色细胞。意义 * 这个发现为基础的研究计划将解决有关S生理反应的重要和独特的问题。金黄色葡萄球菌对杀微生物脂肪酸的能力，以及S.金黄色葡萄球菌对这些化合物产生耐药性。