The Staphylococcus aureus response to nutrient zinc restriction during infection

项目总结 金黄色葡萄球菌是发病率和死亡率的一个重要原因，其发病率和死亡率正在日益增加。 对所有可用的抗生素都有抗药性。抗菌药物开发的一个很有希望的领域是靶向 细菌对营养金属的获取和利用。这种策略利用了这样一个事实，即所有的细菌 病原体需要营养金属来定植它们的宿主。为了回应这一要求，脊椎动物有 进化出强大的防御策略，在一个过程中隔离营养金属和入侵病原体 即所谓的营养免疫力。免疫系统最有效的金属螯合因子之一是 钙保护素是一种丰富的蛋白质，可以隔离营养物质锰、铁和锌，并防止 微生物感染。除了它的金属螯合特性，钙保护素也是一种有效的促炎药物。 分子。这些活动中的每一项对预防感染的个别重要性并不是 分析，并且钙保护素金属结合对其免疫调节特性的贡献尚不清楚。 流行的模型表明，营养免疫确保病原体一致缺乏金属。 在脊椎动物殖民期间。我们通过创新的应用挑战了这一概念 成像技术显示，金黄色葡萄球菌在脓肿中不同地缺乏金属。这一发现 有必要对金黄色葡萄球菌在感染期间遇到的环境进行重新评估，特别是在 与营养金属水平有关。我们还发现金黄色葡萄球菌对金属限制的反应 包括新描述的锌金属配位配位酮COG0523家族成员的上调。 我们的初步结果显示，这些酶使金黄色葡萄球菌能够对抗钙保护素介导的锌。 通过将锌输送到与基因组维持有关的关键金属蛋白而耗尽。 根据这些基本的发现，我们假设在脊椎动物的殖民之后 宿主金黄色葡萄球菌通过将钙保护素传递到宿主部位而遭遇免疫介导的金属限制 感染的可能性。作为回应，金黄色葡萄球菌上调了系统的表达，以对抗这种营养限制。 我们设想这种微生物反应是异质的，并且以一种依赖于水平的方式发生。 在不同的感染部位经历的金属限制。最后，我们预测， 这种对营养限制的反应是专用金属配位酮的上调，这种金属配位酮将金属输送到 参与DNA修复的蛋白质，在暴露于活性氧爆发时是生存所必需的 吞噬细胞。本方案中的实验将通过(I)定义异种金黄色葡萄球菌来检验该模型 对金属饥饿的反应，(Ii)阐明钙保护素预防感染的机制， 以及(Iii)确定金黄色葡萄球菌在金属剥夺过程中获得的金属的亚细胞命运。这部作品 将为理解营养免疫的重要性提供一个机械框架 细菌感染并揭示相应的金黄色葡萄球菌对这种宿主的防御反应。

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.