A Trans-encoded sRNA rli34 is Involved in Virulence Modulation in Listeria monocytogenes

The sRNA is an important regulatory molecule that plays a key role in virulence and environmental adaptive responses in bacteria. To explore the role of sRNA rli34 in virulence of Listeria monocytogenes (L. monocytogenes), here, the molecular features of trans-encoded sRNA rli34 and its intracellular and extracellular expression profiles were characterized. Furthermore, the effects of rli34 gene deletion on virulence were investigated. Meanwhile, target genes regulated by rli34 were predicted and analyzed and rli34-mRNA interactions were validated using a bacterial dual plasmid reporter system based on E. coli. The results showed that rli34 was trans-encoded sRNA and highly conserved in L. monocytogenes, and its intracellular expression level was increased by 10.94-fold as compared to extracellular condition. Moreover, compared with LM EGD-e and LM-Delta rli34-rli34, the adhesion, invasion, intracellular survival and cell inhibition of LM-Delta rli34 on RAW264.7 cells were significantly declined (P<0.05). Furthermore, there were significant differences in bacterial loads in both liver and spleen (P<0.01), and the virulence of LM-orli34 was significantly dampened. Bioinformatics analysis revealed that rli34 could complementarily pair with 5'-UTR (-279 to -270) bases of wall teichoic acids (WTAs) glycosyltransferase (gtcA) mRNA, whereby it promoted the expression of gtcA gene. These findings suggested that this novel trans-encoded sRNA rli34 may facilitate the glycosylation of cell WTAs by targeting gtcA mRNA, thereby precisely modulating the virulence of L. monocytogenes. This study provided new insights into the mechanisms of trans-encoded sRNAs in virulence modulation in L. monocytogenes.

Automated summary

Explored the role of sRNA rli34 in virulence modulation of Listeria monocytogenes, and identified its interaction with the gtcA gene as a mechanism for regulating bacterial virulence. These findings provide new insights into the regulatory mechanisms of trans-encoded sRNAs in L. monocytogenes virulence modulation.