Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.
Departmento de Ciencias de la Vida, Universidad de las Fuerzas Armadas ESPE, Sangolquí, Ecuador.
mBio. 2019 Aug 6;10(4):e01321-19. doi: 10.1128/mBio.01321-19.
During infection, bacteria use two-component signal transduction systems to sense and adapt to the dynamic host environment. Despite critically contributing to infection, the activating signals of most of these regulators remain unknown. This also applies to the ArlRS two-component system, which contributes to virulence by coordinating the production of toxins, adhesins, and a metabolic response that enables the bacterium to overcome host-imposed manganese starvation. Restricting the availability of essential transition metals, a strategy known as nutritional immunity, constitutes a critical defense against infection. In this work, expression analysis revealed that manganese starvation imposed by the immune effector calprotectin or by the absence of glycolytic substrates activates ArlRS. Manganese starvation imposed by calprotectin also activated the ArlRS system even when glycolytic substrates were present. A combination of metabolomics, mutational analysis, and metabolic feeding experiments revealed that ArlRS is activated by alterations in metabolic flux occurring in the latter half of the glycolytic pathway. Moreover, calprotectin was found to induce expression of staphylococcal leukocidins in an ArlRS-dependent manner. These studies indicated that ArlRS is a metabolic sensor that allows to integrate multiple environmental stresses that alter glycolytic flux to coordinate an antihost response and to adapt to manganese starvation. They also established that the latter half of glycolysis represents a checkpoint to monitor metabolic state in Altogether, these findings contribute to understanding how invading pathogens, such as , adapt to the host during infection and suggest the existence of similar mechanisms in other bacterial species. Two-component regulatory systems enable bacteria to adapt to changes in their environment during infection by altering gene expression and coordinating antihost responses. Despite the critical role of two-component systems in bacterial survival and pathogenesis, the activating signals for most of these regulators remain unidentified. This is exemplified by ArlRS, a global regulator that contributes to virulence and to resisting host-mediated restriction of essential nutrients, such as manganese. In this report, we demonstrate that manganese starvation and the absence of glycolytic substrates activate ArlRS. Further investigations revealed that ArlRS is activated when the latter half of glycolysis is disrupted, suggesting that monitors flux through the second half of this pathway. Host-imposed manganese starvation also induced the expression of pore-forming toxins in an ArlRS-dependent manner. Cumulatively, this work reveals that ArlRS acts as a sensor that links nutritional status, cellular metabolism, and virulence regulation.
在感染过程中，细菌利用双组分信号转导系统来感知和适应动态的宿主环境。尽管这些调节剂对于感染至关重要，但大多数调节剂的激活信号仍然未知。这同样适用于 ArlRS 双组分系统，该系统通过协调毒素、黏附素的产生和代谢反应来促进毒力，使细菌能够克服宿主施加的锰饥饿。限制必需过渡金属的可用性，即营养免疫策略，是对抗感染的关键防御措施。在这项工作中，表达分析表明，免疫效应物钙卫蛋白或糖酵解底物缺失引起的锰饥饿激活了 ArlRS。即使存在糖酵解底物，钙卫蛋白引起的锰饥饿也会激活 ArlRS 系统。代谢组学、突变分析和代谢喂养实验的组合表明，ArlRS 是通过糖酵解途径后半段发生的代谢通量变化而激活的。此外，发现钙卫蛋白以依赖于 ArlRS 的方式诱导葡萄球菌白细胞毒素的表达。这些研究表明，ArlRS 是一种代谢传感器，使能够整合改变糖酵解通量的多种环境应激，以协调抗宿主反应并适应锰饥饿。它们还表明，糖酵解的后半部分代表一个检查点，以监测代谢状态。总之，这些发现有助于了解像这样的入侵病原体如何在感染过程中适应宿主，并表明其他细菌物种中存在类似的机制。双组分调节系统使细菌能够通过改变基因表达和协调抗宿主反应来适应感染期间环境的变化。尽管双组分系统在细菌的生存和发病机制中起着关键作用，但大多数这些调节剂的激活信号仍然未知。ArlRS 就是一个例子，它是一种全局性调节因子，有助于毒力和抵抗宿主介导的必需营养物质（如锰）的限制。在本报告中，我们证明了锰饥饿和糖酵解底物的缺乏激活了 ArlRS。进一步的研究表明，当糖酵解的后半部分被破坏时，ArlRS 被激活，这表明在这条途径的后半部分监测通量。宿主施加的锰饥饿也以依赖于 ArlRS 的方式诱导孔形成毒素的表达。总的来说，这项工作表明，ArlRS 作为一种传感器，将营养状况、细胞代谢和毒力调节联系起来。
