A QUORUM-SENSING-REGULATED SMALL RNA THAT CONTROLS PRODUCTION OF THE OUTER MEMBRANE PROTEIN OMPA IN VIBRIO HARVEYI

Abstract

Bacteria use a cell-cell communication process called quorum sensing (QS) to transition between individual and community lifestyles. QS relies on the production, secretion, detection, and response to extracellular signaling molecules called autoinducers (AI) that increase in concentration in step with increases in bacterial population density. In Vibrio harveyi, transitions into and out of QS mode are driven by five homologous small RNAs (sRNAs) called Qrr1-5 that control the production of AphA and LuxR, the master low-cell density and master high-cell density QS regulators, respectively. Using high-throughput whole genome microarrays, we discover a sRNA that we name QsrA (Quorum-sensing-regulated sRNA A) that is activated by LuxR and repressed by AphA. This regulatory arrangement ensures maximal production of QsrA at high-cell density. QsrA, in turn, post-transcriptionally controls multiple mRNA targets. One target, VIBHAR_04892 encoding the outer membrane protein A (OmpA) is activated more than 60-fold by QsrA at high-cell density. Gene-fusion and epistasis analyses suggest there exists an intermediate factor through which QsrA controls ompA.