Davis Richard W, Muse Charlotte G, Eggleston Heather, Hill Micaila, Panizzi Peter
Department of Drug Discovery and Development, Auburn University, Auburn, AL, United States.
Front Microbiol. 2022 Jun 2;13:864014. doi: 10.3389/fmicb.2022.864014. eCollection 2022.
() can thrive in its host during an infection, and, as a result, it must be able to respond to external stimuli and available carbon sources. The preclinical use of engineered pathogens capable of constitutive light production may provide real-time information on microbial-specific metabolic processes. In this study, we mapped the central metabolism of a -modified Xen20 (. Xen20) to its synthesis of luciferase substrates as assessed by the rate of light production in response to different environmental triggers. Previous characterization predicted that the operon was under the myo-inositol promotor. In this study, we revealed that supplementation with myo-inositol generated increased Xen20 luminescence. Surprisingly, when supplemented with infection-relevant carbon sources, such as glucose or glycine, light production was diminished. This was presumably due to the scavenging of pyruvate by -lactate dehydrogenase (LDH). Inhibition of LDH by its inhibitor, oxamate, partially restored luminescent signal in the presence of glucose, presumably by allowing the resulting pyruvate to proceed to acetyl-coenzyme A (CoA). This phenomenon appeared specific to the lactic acid bacterial metabolism as glucose or glycine did not reduce signal in an analogous -modified Gram-positive pathogen, . Xen29. The Xen20 cells produced light in a concentration-dependent manner, inversely related to the amount of glucose present. Taken together, our measures of microbial response could provide new information regarding the responsiveness of metabolism to acute changes in its local environments and cellular health.
（）在感染期间能够在其宿主中茁壮成长，因此，它必须能够对外部刺激和可用碳源做出反应。能够持续发光的工程病原体的临床前应用可能会提供有关微生物特异性代谢过程的实时信息。在本研究中，我们将一种经过修饰的Xen20（.Xen20）的中心代谢与其荧光素酶底物的合成进行了映射，这是通过响应不同环境触发因素的发光速率来评估的。先前的表征预测该操纵子受肌醇启动子调控。在本研究中，我们发现补充肌醇会使Xen20的发光增加。令人惊讶的是，当补充与感染相关的碳源，如葡萄糖或甘氨酸时，发光会减弱。这可能是由于乳酸脱氢酶（LDH）对丙酮酸的清除。其抑制剂草氨酸对LDH的抑制在存在葡萄糖的情况下部分恢复了发光信号，大概是通过使产生的丙酮酸进入乙酰辅酶A（CoA）。这种现象似乎是乳酸菌代谢特有的，因为葡萄糖或甘氨酸不会降低类似的经过修饰的革兰氏阳性病原体.Xen29中的信号。Xen20细胞以浓度依赖的方式产生光，与存在的葡萄糖量呈负相关。综上所述，我们对微生物反应的测量可以提供有关代谢对其局部环境和细胞健康急性变化的反应性的新信息。
