Adaptation of Staphylococcus aureus to Mn and Zn starvation imposed by the host

描述（由申请方提供）：由于抗生素耐药性增加，细菌感染是全球关注的重大问题。金黄色葡萄球菌是一种值得警惕的病原体，因为这种细菌几乎能够感染人体的每一个部位。这种适应性与抗生素耐药性的增加相结合，导致与葡萄球菌感染相关的高发病率和死亡率。脊椎动物利用这一有力的策略 对抗细菌病原体的关键是隔离必需营养素，这一过程被称为营养免疫。最近的研究发现，在侵袭性葡萄球菌疾病期间，成熟的葡萄球菌几乎缺乏锰（Mn）和锌（Zn）。进一步的研究表明，在葡萄球菌感染过程中锰的螯合依赖于中性粒细胞蛋白钙卫蛋白（CP），S100A8和S100A9的异二聚体。CP是能够结合一个锰离子和两个锌离子与纳摩尔的亲和力，这表明不仅在锰扣留，但也在锌螯合的作用。在小鼠感染模型中，CP缺陷小鼠葡萄球菌负荷增加，表明S。金黄色葡萄球菌在感染期间是Mn饥饿的。这一观点进一步得到以下观察结果的支持：在感染期间，锰依赖性细菌过程受到抑制。总之，这些结果表明脊椎动物引起S。金黄色葡萄球菌在感染期间变得Mn和Zn饥饿，并且这种饥饿对于宿主防御至关重要。尽管脊椎动物创造了一个几乎没有锰和锌的环境，但S。金黄色葡萄球菌仍然能够引起重大和毁灭性的疾病。这些观察导致了S.金黄色葡萄球菌必须以某种方式适应宿主施加的Mn和Zn限制。S.已知金黄色葡萄球菌编码专用的Mn和Zn转运蛋白，其可以帮助该病原体抵抗脊椎动物金属螯合的作用。然而，CP缺陷小鼠中葡萄球菌毒力的增加表明S.金黄色葡萄球菌不足以防止金属饥饿。尽管已知 脊椎动物螯合锰和锌，这一过程的动力学尚未阐明，和金属饥饿的程度强加给S。金黄色葡萄球菌仍然未知。此外，S.金黄色葡萄球菌对CP胁迫下Mn和Zn饥饿的抵抗和适应尚不清楚。目前的项目集中在阐明锰和锌螯合的时间，被破坏的细菌过程，这种主机防御，以及专用的锰和锌进口系统的贡献，以抵抗CP。一旦获得教职，调查将集中在确定S。金黄色葡萄球菌适应Mn和Zn饥饿。本申请中提出的工作将跟踪观察到ArlRS双组分调节系统和S.金黄色葡萄球菌促进对宿主施加的Mn和Zn限制的抗性。本提案的具体目标如下：评估ArlRS调节和碳源偏好改变对促进S.金黄色葡萄球菌对宿主施加的Mn和Zn限制的适应。Aim II.确定S的各个角色。金黄色葡萄球菌超氧化物歧化酶在抵抗宿主施加的金属饥饿中的作用。除了对S.金黄色葡萄球菌用来逃避宿主防御的一个重要手段，这个建议将有利于我独立研究事业的发展。我的长期目标是了解宿主和病原体之间的相互作用如何影响疾病的发展。为了追求这一目标，我在圣路易斯的华盛顿大学获得了研究生学位，重点是分子微生物学和微生物发病机制，随后在范德比尔特大学与Eric Skaar博士一起进行了葡萄球菌发病机制和金属生物学的博士后培训。我的近期目标是获得一个教职，并建立一个高效的独立研究计划。范德比尔特大学对博士后培训的承诺，其中包括提供如何运行一个成功的独立实验室的研讨会，大大增强了我实现这一目标的能力。为了促进从博士后研究员到独立研究员的成功过渡，我将寻求我未来所在机构的资深科学家和已建立的非正式顾问网络的建议和咨询。我还将积极寻求机会，发展技能， 运行一个成功的独立实验室，并培养新的合作。结合起来，拟议的调查和职业发展活动将为独立研究计划的发展提供良好的基础。

DESCRIPTION (provided by applicant): Bacterial infections are of substantial global concern due to increasing antibiotic resistance. Staphylococcus aureus is a pathogen of alarm because of the ability of the bacterium to infect nearly every site in the human body. This adaptability combined with increasing antibiotic resistance results in the high levels of morbidity and mortality associated with staphylococcal infections. A powerful strategy utilized by vertebrates to combat bacterial pathogens is the sequestration of essential nutrients, a process known as nutritional immunity. Recent work found that during invasive staphylococcal disease mature abscesses are virtually devoid of manganese (Mn) and zinc (Zn). Further work revealed that the sequestration of Mn during staphylococcal infection is dependent on the neutrophil protein calprotectin (CP), a heterodimer of S100A8 and S100A9. CP is capable of binding one Mn ion and two Zn ions with nanomolar affinity, suggesting a role not only in Mn withholding but also in Zn sequestration. In a murine model of infection, CP-deficient mice have increased staphylococcal burdens, indicating that S. aureus is Mn starved during infection. This idea is further supported by the observation that during infection Mn-dependent bacterial processes are inhibited. In total, these results suggest that vertebrates cause S. aureus to become Mn and Zn starved during infection and that this starvation is critical to host defense. Even though vertebrates create an environment virtually devoid of Mn and Zn, S. aureus remains capable of causing significant and devastating disease. These observations led to the hypothesis that S. aureus must somehow adapt to the Mn and Zn limitation imposed by the host. S. aureus is known to encode dedicated Mn and Zn transporters that may help this pathogen resist the effects of vertebrate metal sequestration. However, the increased staphylococcal virulence in CP-deficient mice suggests that expression of Mn transporters, and presumably Zn transporters, by S. aureus is not sufficient to prevent metal starvation. Although it is known that vertebrates sequester Mn and Zn, the kinetics of this process have not been elucidated, and the extent of metal starvation imposed on S. aureus remain unknown. Furthermore, how S. aureus resists and adapts to Mn and Zn starvation imposed by CP remains unclear. Current projects are focused on elucidating the timing of Mn and Zn sequestration, the bacterial processes that are disrupted by this host defense, and the contribution of dedicated Mn and Zn import systems to resisting CP. Once a faculty position has been obtained, investigations will focus on determining how S. aureus adapts to Mn and Zn starvation. The work proposed in this application will follow up on the observations that the ArlRS two-component regulatory system and the two Mn-dependent superoxide dismutases expressed by S. aureus promote resistance to host imposed Mn and Zn limitation. The Specific Aims of this proposal are as follows: Aim I. Evaluate the role of ArlRS regulation and alterations in carbon source preference to facilitating S. aureus adaptation to host-imposed Mn and Zn limitation. Aim II. Determine the individual roles of S. aureus superoxide dismutases in resisting host-imposed metal starvation. In addition to providing substantial insight into the mechanisms that S. aureus uses to evade an important host defense, this proposal will facilitate the development of my independent research career. My long-term goal is to understand how the interactions between host and pathogen influence disease development. In pursuit of this goal, I obtained my graduate degree from Washington University in St. Louis with an emphasis in Molecular Microbiology and Microbial Pathogenesis followed by postdoctoral training in staphylococcal pathogenesis and metals biology with Dr. Eric Skaar at Vanderbilt University. My immediate goal is to obtain a faculty position and establish a highly productive independent research program. The commitment of Vanderbilt University to postdoctoral training, which includes offering seminars on how to run a successful independent laboratory, has substantially enhanced my ability to achieve this goal. To promote a successful transition from postdoctoral fellow to independent investigator, I will seek out advice and counsel from senior scientists at my future institution and an established network of informal advisors. I will also actively pursue opportunities to develop skills that will facilitate running a successful independent laboratory, and cultivate new collaborations. In combination, the proposed investigations and career development activities will provide an excellent foundation for the development of an independent research program.