RyhB is a key regulator of iron level in Escherichia coli (E. coli), which assists in conserving iron for life-sustaining cellular functions when cytoplasmic levels of the ferrous form of iron is limited. RyhB affects glucose metabolism. Seventy percent of the genes that are regulated by RyhB are related to metabolism. We demonstrated for the first time that the activity of the pentose phosphate pathway increased upon ryhB activation using a13C stable isotope-based technique called METAFoR (Metabolic flux ratio analysis). U-13C glucose-based studies showed that the reversible exchange activity of serine and glycine was enhanced by flux redistribution, which further favors NADPH formation. In addition, Entner-Doudoroff (ED) pathway activity was inhibited in the ryhB-defective cells. Quantitative physiology-based experiments highlighted a significant increase in the levels of reactive oxygen species (ROS) in ryhB-induced W3100 E. coli cells in batch culture. A simultaneous decrease in NADH/NAD+ and NADPH/NADP+ ratios outlined the potentially direct roles of NADH and NADPH in antagonizing the excess ROS formed after ryhB activation. Our observations offer a new perspective regarding the roles of RyhB and highlight that this small RNA can significantly affect cell metabolism in addition to its role as a regulator of gene expression.

中文翻译：

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细菌小RNA RyhB对大肠杆菌W3100的代谢和生理扰动。

RyhB是大肠杆菌（E. coli）中铁水平的关键调节剂，当铁的亚铁形式的细胞质水平受到限制时，RyhB有助于保存铁以维持生命的细胞功能。RyhB影响葡萄糖代谢。RyhB调控的基因中有70％与代谢有关。我们首次证明，使用基于13C稳定同位素的技术METAFoR（代谢通量比分析），通过ryhB激活，戊糖磷酸途径的活性增加。基于U-13C葡萄糖的研究表明，通量重新分布增强了丝氨酸和甘氨酸的可逆交换活性，这进一步促进了NADPH的形成。此外，在ryhB缺陷细胞中Entner-Doudoroff（ED）通路活性受到抑制。基于定量生理学的实验突出了分批培养中ryhB诱导的W3100大肠杆菌细胞中活性氧（ROS）水平的显着提高。NADH / NAD +和NADPH / NADP +比率的同时下降概述了NADH和NADPH在拮抗ryhB激活后形成的过量ROS方面的潜在直接作用。我们的观察结果为RyhB的作用提供了新的视角，并强调了这一小RNA除了作为基因表达的调节剂之外，还可以显着影响细胞的代谢。