Iron independent role for yersiniabactin in Yersinia pestis

摘要 细菌需要过渡金属（例如铁、锌、锰）才能生长。因此，哺乳动物具有 在感染过程中隔离这些金属的多种机制，有效地限制了它们的使用 细菌（称为营养免疫）。鼠疫耶尔森氏菌（Yersinia pestis）是导致人类瘟疫的原因，需要 进化出高亲和力的金属获取机制来克服营养免疫并殖民其宿主。 由于这些机制是鼠疫耶尔森氏菌毒力的关键，因此它们代表了鼠疫耶尔森氏菌的潜在治疗靶点。 治疗或预防鼠疫。因此，我们的长期目标是确定 Y 使用的机制。 鼠疫菌逃避宿主营养免疫并确定其毒力作用。最近，我们做了令人兴奋的 发现鼠疫杆菌铁 (Fe) 获取所必需的铁载体耶尔森菌素 (Ybt) 也能够结合 锌 (Zn)，并有助于体外锌的获取。此外，使用血色素沉着症小鼠模型 由于 Fe 介导的营养免疫存在缺陷，我们首次证明 Ybt 有助于 以不依赖于 Fe 的方式产生毒力。使用在锌获取方面有缺陷的鼠疫耶尔森氏菌突变体，还表明 宿主蛋白钙卫蛋白是锌介导的营养免疫的关键成分，是锌介导的营养免疫的屏障 鼠疫耶尔森氏菌感染和 Ybt 有助于克服肺鼠疫和黑死病中的这一障碍。 总之，这些数据是我们提出概念创新假设的前提，即 Ybt 不仅有助于 通过获取铁来产生毒力，但也有助于获取锌，这有助于克服钙卫蛋白 介导的营养免疫。在本提案中，我们将以这些令人兴奋的发现为基础。在目标 1 中，我们将定义 控制 Ybt 金属选择性和细菌重新获取 Ybt-Zn 的机制。在目标 2 中， 我们将定义鼠疫耶尔森氏菌使用的 Ybt 分泌机制并确定其治疗潜力 在鼠疫期间抑制这些分泌系统。最后，在目标 3 中，我们将定义宿主钙卫蛋白的作用 鼠疫期间 Ybt 对鼠疫耶尔森氏菌克服钙卫蛋白介导的锌的能力的贡献 封存。重要的是，Ybt 是许多革兰氏阴性细菌中保守的毒力因子。因此， 这些研究产生的数据有可能使我们对 Ybt 的作用有更广泛的了解 多种病原体的毒力。最终，这些数据将为合理设计提供基础。 针对这些机制来对抗鼠疫耶尔森氏菌感染的新治疗方法。

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.