Oligonucleotides used in RT-qPCR assay.

The 24B_1 small non-coding RNA molecule has been identified in Escherichia coli after induction of Shiga toxin-converting bacteriophage Φ24B. In this work, we focused on its direct role during phage and bacterial host development. We observed that in many aspects, this phage sRNA resembles herpesviral microRNAs. Similar to microRNAs, the mature 24B_1 is a short molecule, consisting of just 20 nucleotides. It is generated by cleaving the 80-nt long precursor transcript, and likely it undergoes a multi-step maturation process in which the Hfq protein plays an important role, as confirmed by demonstration of its binding to the 24B_1 precursor, but not to the 24B_1 mature form. Moreover, 24B_1 plays a significant role in maintaining the prophage state and reprogramming the host’s energy metabolism. We proved that overproduction of this molecule causes the opposite physiological effects to the mutant devoid of the 24B_1 gene, and thus, favors the lysogenic pathway. Furthermore, the 24B_1 overrepresentation significantly increases the efficiency of expression of phage genes coding for proteins CI, CII, and CIII which are engaged in the maintenance of the prophage. It seems that through binding to mRNA of the sdhB gene, coding for the succinate dehydrogenase subunit, the 24B_1 alters the central carbon metabolism and causes a drop in the ATP intracellular level. Interestingly, a similar effect, called the Warburg switch, is caused by herpesviral microRNAs and it is observed in cancer cells. The advantage of the Warburg effect is still unclear, however, it was proposed that the metabolism of cancer cells, and all rapidly dividing cells, is adopted to convert nutrients such as glucose and glutamine faster and more efficiently into biomass. The availability of essential building blocks, such as nucleotides, amino acids, and lipids, is crucial for effective cell proliferation which in turn is essential for the prophage and its host to stay in the lysogenic state.在志贺毒素转化性噬菌体Φ24B诱导后，科研人员在大肠杆菌（Escherichia coli）中成功鉴定出24B_1小型非编码RNA（small non-coding RNA, sRNA）分子。本研究聚焦于该RNA在噬菌体与宿主细菌发育进程中的直接调控作用。我们观察到，该噬菌体来源的小非编码RNA在诸多方面与疱疹病毒微RNA（microRNA, miRNA）相似。与微RNA类似，成熟的24B_1是一段仅含20个核苷酸的短链RNA分子，由80核苷酸长度的前体转录本经剪切产生，且大概率经历多步骤成熟过程——其中Hfq蛋白发挥关键作用，这一点已通过其与24B_1前体而非成熟24B_1分子的结合实验得到证实。此外，24B_1在维持原噬菌体（prophage）状态以及重编程宿主能量代谢方面发挥重要功能。本研究证实，该RNA分子的过表达与缺失24B_1基因的突变株呈现相反的生理表型，因此该RNA倾向于促进溶原途径。此外，24B_1的过量表达可显著提升噬菌体CI、CII及CIII蛋白编码基因的表达效率，这些蛋白均参与原噬菌体的维持过程。研究表明，24B_1可通过结合编码琥珀酸脱氢酶（succinate dehydrogenase）亚基的sdhB基因的mRNA，改变宿主中央碳代谢途径，并导致细胞内ATP水平下降。值得注意的是，疱疹病毒微RNA亦可引发类似效应——即所谓的沃伯格转换（Warburg switch），该效应在癌细胞中已有报道。沃伯格效应的生物学优势目前仍不明确，但已有假说提出，癌细胞与所有快速增殖细胞的代谢模式均倾向于将葡萄糖、谷氨酰胺等营养物质更快速高效地转化为生物量。核苷酸、氨基酸、脂质等关键生物合成前体的可获得性，对于高效的细胞增殖至关重要；而细胞增殖反过来又是原噬菌体及其宿主维持溶原状态的必要条件。