Iron independent role for yersiniabactin in Yersinia pestis

摘要 过渡金属(如铁、锌、锰)是细菌生长所必需的。因此，哺乳动物有一种 在感染期间隔离这些金属的各种机制，有效地限制了它们在 细菌(简称营养免疫)。引起人类疾病鼠疫的鼠疫耶尔森氏菌需要 进化高亲和力的金属获取机制，以克服营养免疫并定植宿主。 由于这些机制是鼠疫杆菌毒力的关键，它们代表着潜在的治疗靶点 瘟疫的治疗或预防。因此，我们的长期目标是确定Y使用的机制。 鼠疫逃避宿主的营养免疫，并确定它们在毒力中的作用。最近，我们制作了令人兴奋的 发现Yersiniabactin(Ybt)，一种获取鼠疫菌铁(Fe)所必需的铁载体，也能够结合 对锌的吸收，并有助于锌的体外获取。此外，使用血色素沉着症小鼠模型 在铁介导的营养免疫方面存在缺陷，我们首次证明了Ybt对 毒力不依赖于铁。还显示了使用在获取锌方面存在缺陷的鼠疫耶尔森菌突变体 宿主蛋白钙保护素是锌介导的营养免疫的关键成分，是一种屏障 鼠疫杆菌感染，Ybt有助于克服肺鼠疫和腺鼠疫的这一障碍。 总而言之，这些数据是我们提出概念创新假设的前提，Ybt不仅有助于 毒力通过铁的获取，但也有助于锌的获取，这有助于克服钙保护 介导的营养免疫。在这个提案中，我们将在这些令人兴奋的发现的基础上再接再厉。在目标1中，我们将定义 控制Ybt对金属的选择性和细菌对Ybt-Zn的再获取的机制。在目标2中， 我们将定义鼠疫杆菌使用的Ybt分泌机制，并确定其治疗潜力 在瘟疫期间抑制这些分泌系统。最后，在目标3中，我们将定义主机调用保护的角色 鼠疫期间Ybt对鼠疫杆菌克服钙保护素介导的锌的作用 自动减支。重要的是，Ybt在许多革兰氏阴性菌中是一个保守的毒力因子。因此， 这些研究产生的数据有可能使我们对Ybt的作用有更广泛的理解 多种病原体的毒力。最终，这些数据将为合理的设计提供基础 针对这些机制的新的治疗方法，以对抗鼠疫杆菌感染。

SUMMARY Transitional metals (e.g., Fe, Zn, Mn) are required by bacteria in order to grow. As such, mammals have a variety of mechanisms to sequester these metals during infection, effectively limiting their availability for use by bacteria (referred to as nutritional immunity). Yersinia pestis, which causes the human disease plague, needed to evolve high-affinity metal acquisition mechanisms to overcome nutritional immunity and colonize its hosts. Because these mechanisms are key to Y. pestis virulence, they represent potential therapeutic targets for the treatment or prevention of plague. Therefore, our long term goals are to identify the mechanisms used by Y. pestis to evade host nutritional immunity and define their roles in virulence. Recently, we have made the exciting discovery that yersiniabactin (Ybt), a siderophore essential for Y. pestis iron (Fe) acquisition, is also able to bind to zinc (Zn), and contributes to Zn acquisition in vitro. Furthermore, using a hemochromatosis mouse model that is defective in Fe-mediated nutritional immunity, we demonstrated for the first time that Ybt contributes to virulence in an Fe-independent manner. Using a Y. pestis mutant defective in Zn acquisition, was also showed that the host protein calprotectin, which is a key component to Zn-mediated nutritional immunity, is a barrier to Y. pestis infection, and Ybt contributes to overcoming this barrier in both pneumonic and bubonic plague. Together, these data are our premise for the conceptually innovative hypothesis that Ybt not only contributes to virulence through Fe acquisition, but also contributes to Zn acquisition, which aids in overcoming calprotectin mediated nutritional immunity. In this proposal, we will build on these exciting discoveries. In Aim 1, we will define the mechanisms that govern metal selectivity of Ybt and the re-acquisition of Ybt-Zn by the bacterium. In Aim 2, we will define the Ybt secretion mechanisms used by Y. pestis and determine the therapeutic potential of inhibiting these secretion systems during plague. Finally, in Aim 3, we will define the role of host calprotectin during plague and the contribution of Ybt to the ability of Y. pestis in overcoming calprotectin mediated Zn sequestration. Importantly, Ybt is a conserved virulence factor in many Gram-negative bacteria. Therefore, the data generated from these studies has the potential to provide us with a broader understanding of the role of Ybt in the virulence of multiple pathogens. Ultimately, these data will provide a foundation for the rational design of new therapeutic approaches targeting these mechanisms to combat Y. pestis infection.