Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, PR China; Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin 300072, PR China.
Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, PR China.
Biochem Biophys Res Commun. 2018 Jun 7;500(3):544-549. doi: 10.1016/j.bbrc.2018.04.069. Epub 2018 Apr 22.
Lactococcus lactis, a gram-positive bacterium, encounters various environmental stresses, especially acid stress, during fermentation. Small RNAs (sRNAs) that serve as regulators at post-transcriptional level play important roles in acid stress response. Here, a novel sRNA S042 was identified by RNA-Seq, RT-PCR and Northern blot. The transcription level of s042 was upregulated 2.29-fold under acid stress by Quantitative RT-PCR (qRT-PCR) analysis. Acid tolerance assay showed that overexpressing s042 increased the survival rate of L. lactis F44 and deleting s042 significantly inhibited the viability under acidic conditions. Moreover, the targets were predicted by online software and four genes were chosen as candidates. Among them, argR (arginine regulator) and accD (acetyl-CoA carboxylase carboxyl transferase subunit beta) were validated to be the direct targets activated by S042 through reporter fusion assay. The regulatory mechanism between S042 and its targets was further investigated through Bioinformatics and qRT-PCR. This study served to highlight the role of the novel sRNA S042 in acid resistance of L. lactis and provided new insights into the response mechanism of acid stress.
乳球菌是一种革兰氏阳性菌，在发酵过程中会遇到各种环境压力，特别是酸应激。在转录后水平起调控作用的小 RNA（sRNA）在酸应激反应中发挥着重要作用。本研究通过 RNA-Seq、RT-PCR 和 Northern blot 鉴定到一个新型 sRNA S042。定量 RT-PCR（qRT-PCR）分析表明，s042 在酸胁迫下的转录水平上调了 2.29 倍。酸耐受试验表明，过表达 s042 可提高 L. lactis F44 的存活率，而删除 s042 则显著抑制了其在酸性条件下的活力。此外，通过在线软件预测靶基因，并选择了四个基因作为候选基因。其中，argR（精氨酸调节因子）和 accD（乙酰辅酶 A 羧化酶羧基转移酶亚基β）通过报告基因融合实验被验证为 S042 的直接靶标。通过生物信息学和 qRT-PCR 进一步研究了 S042 与其靶基因之间的调控机制。本研究强调了新型 sRNA S042 在乳球菌耐酸中的作用，并为酸应激响应机制提供了新的见解。
