The Staphylococcus aureus response to nutrient zinc restriction during infection

项目摘要 金黄色葡萄球菌是发病率和死亡率的重要原因， 对所有可用的抗生素产生耐药性。一个有希望的抗菌开发领域涉及靶向 细菌对营养金属的获取和利用。这种策略利用了所有细菌 病原体需要营养金属来定殖它们的宿主。为了满足这一要求，脊椎动物 进化出了强大的防御策略， 称为营养免疫。免疫系统最有效的金属螯合因子之一是 钙卫蛋白是一种丰富的蛋白质，可以螯合营养物质锰、铁和锌， 微生物感染除了它的金属螯合特性，钙卫蛋白是一种有效的促炎剂， 分子。这些活动中的每一种对预防感染的个别重要性尚未得到证实。 解析，并且钙卫蛋白金属结合对其免疫调节性质的贡献尚不清楚。 流行的模型表明，营养免疫确保病原体均匀地缺乏金属 在脊椎动物的殖民过程中。我们通过应用创新的 成像技术，揭示了S.金黄色葡萄球菌是差异性的金属饥饿的范围内。这一发现 需要重新评估S所遇到的环境。在感染过程中，特别是当它 与营养金属水平有关。我们还发现S.金葡菌对金属限制的反应 包括锌金属伴侣蛋白的新描述的COG0523家族成员的上调。 我们的初步结果表明，这些酶使S。金黄色葡萄球菌对抗钙卫蛋白介导的锌 通过将锌递送到参与基因组维持的关键金属蛋白来消耗锌。 基于这些基本的发现，我们假设，在脊椎动物的殖民化之后， host，S.金黄色葡萄球菌遇到免疫介导的金属限制通过钙卫蛋白的传递到该部位 感染作为回应，S.金黄色葡萄球菌上调系统的表达以对抗这种营养限制。 我们设想这种微生物反应是异质的，并且以依赖于水平的方式发生。 在不同的感染部位出现金属限制。最后，我们预测， 这种对营养限制的反应是专用金属伴侣的上调， 参与DNA修复的蛋白质，是暴露于活性氧爆发时生存所必需的。 吞噬细胞本提案中的实验将通过以下方式测试该模型：（i）定义异构S。金黄色 响应金属饥饿，（ii）阐明钙卫蛋白保护免受感染的机制， 和（iii）确定由S.金黄色葡萄球菌在金属剥夺这项工作 将为理解营养免疫的重要性提供一个机制框架， 细菌感染，并显示相应的S.金黄色葡萄球菌对此宿主防御的反应。

PROJECT SUMMARY Staphylococcus aureus is a significant cause of morbidity and mortality that is increasingly acquiring resistance to all available antibiotics. One promising area for antimicrobial development involves targeting bacterial acquisition and utilization of nutrient metal. This strategy exploits the fact that all bacterial pathogens require nutrient metal to colonize their hosts. In response to this requirement, vertebrates have evolved powerful defense strategies that sequester nutrient metals from invading pathogens in a process known as nutritional immunity. One of the most effective metal chelating factors of the immune system is calprotectin, an abundant protein that sequesters nutrient manganese, iron, and zinc and defends against microbial infection. In addition to its metal chelating properties, calprotectin is a potent pro-inflammatory molecule. The individual importance of each of these activities to protection against infection has not been parsed, and the contribution of calprotectin metal binding to its immunomodulatory properties is not known. Prevailing models suggest that nutritional immunity ensures that pathogens are uniformly metal starved during vertebrate colonization. We have challenged this concept through the application of innovative imaging technologies, revealing S. aureus is differentially metal starved within abscesses. This discovery necessitates a reevaluation of the environment encountered by S. aureus during infection, particularly as it pertains to nutrient metal levels. We have also discovered that the S. aureus response to metal restriction includes the up-regulation of members of the newly described COG0523 family of zinc metallochaperones. Our preliminary results reveal that these enzymes enable S. aureus to combat calprotectin-mediated zinc depletion by delivering zinc to critical metalloproteins involved in genome maintenance. Based on these fundamental discoveries, we hypothesize that following colonization of the vertebrate host, S. aureus encounters immune-mediated metal restriction through the delivery of calprotectin to the site of infection. In response, S. aureus up-regulates the expression of systems to combat this nutrient limitation. We envision that this microbial response is heterogeneous, and occurs in a manner dependent on the level of metal restriction experienced at distinct sites of infection. Finally, we predict that an important aspect of this response to nutrient limitation is the up-regulation of dedicated metallochaperones that deliver metal to proteins involved in DNA repair and are required for survival upon exposure to the reactive oxygen burst of the phagocyte. Experiments in this proposal will test this model by (i) defining the heterogeneous S. aureus response to metal starvation, (ii) elucidating the mechanism by which calprotectin protects against infection, and (iii) determining the subcellular fate of metal acquired by S. aureus during metal deprivation. This work will provide a mechanistic framework for understanding the importance of nutritional immunity during bacterial infection and reveal the corresponding S. aureus response to this host defense.