The transcriptomic analysis (RNA‐seq) of a fur mutant of P. pseudoalcaligenes CECT 5344 has revealed that Fur regulates the expression of more than 100 genes in this bacterial strain, most of them negatively. The highest upregulated genes in response to fur deletion, with respect to the wild type, both cultivated in LB medium, corresponded to genes implicated in iron uptake. They include both TonB‐dependent siderophore transporters for the active transport across the outer membrane, and ABC‐type and MSF‐type transporters for the active transport across the cytoplasmic membrane. Therefore, the main response of this bacterium to iron limitation is expressing genes necessary for metabolism of Fe siderophores produced by other microorganisms (xenosiderophores). The number of genes whose expression decreased in the fur− mutant, as well as its normalized expression (fold change), was lower. Among them, it is remarkable the presence of one of the two cas operons of the two CRISP/Cas clusters was detected in the genome of this bacterium. The transcriptome was validated by qPCR, including the decrease in the expression of cas genes (cse1). The expression of cse1 was also decreased by limiting the amount of iron, carbon or nitrogen in the medium, or by adding menadione, a compound that causes oxidative stress. The higher decrease in cse1 expression was triggered by the addition of cyanide in minimal medium. These results suggest that this bacterium responds to stress conditions, and especially to cyanide, taking a reasonable risk with respect to both the uptake of (TonB‐dependent receptors gates) and the tolerance to (reduced immunity) foreign nucleic acids. In conjunction, this can be considered a yet unknown molecular mechanism forcing bacterial evolution.

中文翻译：

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通过对蓝藻细菌Pseudomonas pseudoalcaligenes CECT 5344的fur突变体进行转录组分析，揭示了新的进化策略。

对假拟青假单胞菌CECT 5344的fur突变体进行的转录组分析（RNA-seq）显示，Fur调节了该细菌菌株中100多个基因的表达，其中大多数为阴性。响应皮草的最高上调基因关于野生型的缺失，均在LB培养基中培养，对应于与铁摄取有关的基因。它们既包括TonB依赖型铁载体转运蛋白，用于跨膜的主动转运，也包括ABC型和MSF型转运蛋白，用于跨细胞质膜的主动转运。因此，该细菌对铁限制的主要反应是表达其他微生物产生的铁铁载体代谢所必需的基因（异铁铁载体）。在fur-突变体中表达下降的基因数量及其标准化表达（倍数变化）都较低。其中，值得注意的是，两个cas中的一个在此细菌的基因组中检测到两个CRISP / Cas簇的操纵子。转录组通过qPCR进行了验证，包括cas基因（cse1）表达的减少。通过限制培养基中铁，碳或氮的含量，或通过添加甲萘醌（一种引起氧化应激的化合物），也可以降低cse1的表达。cse1的降低幅度更大通过在基本培养基中添加氰化物来触发表达。这些结果表明，这种细菌对应激条件特别是对氰化物有反应，在摄取（TonB依赖的受体门）和对（降低的免疫力）外来核酸的耐受性方面都承担着合理的风险。结合起来，这可以被认为是强迫细菌进化的未知分子机制。