Regulatory roles of an sRNA derived from the 5´ UTR and sequence internal to <i>lap</i> A in <i>Pseudomonas aeruginosa</i> PAO1

<i>Pseudomonas aeruginosa</i> is a common nosocomial pathogen that contains hundreds of virulence factors regulated by quorum-sensing systems and environmental stress. Small noncoding RNAs (sRNAs) involved in virulence regulation have been identified in <i>P. aeruginosa</i>. Recently, several potential sRNAs were identified in <i>P. aeruginosa</i> using transcriptome sequencing. However, some of these novel sRNAs have been functionally characterized. In this study, a previously uncharacterized sRNA, LapS, in <i>P. aeruginosa</i> PAO1 was identified as a novel sRNA. LapS is involved in regulating swarming motility, rhamnolipid production, and alkaline phosphatase production during phosphate-depleted stress by controlling the level of <i>lapA</i> mRNA. Furthermore, LapS deletion also reduced the mortality rate of <i>Caenorhabditis elegans</i> in a fast-kill assay. Additionally, LapS directly suppressed PutA, a virulence factor of <i>P. aeruginosa</i>. This study highlights the role of LapS in modulating <i>P. aeruginosa</i> virulence during phosphate-depleted stress.