Gene-specific silencing induced by parallel complementary RNA in <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis>

To investigate whether parallel complementary RNA (pRNA) could induce gene-specific silencing in Pseudomonas aeruginosa, pRNA of the mexA gene was expressed in it. Compared to the control strains, the strain expressing pRNA of mexA showed a 50% decrease in minimum inhibitory concentrations (MICs) of several antimicrobial agents and a twofold increase in the initial accumulation rate of ethidium bromide, all of which are substrates of the MexAB-OprM efflux pump. These results suggest that gene-specific silencing was induced by pRNA. This is the first time that such a route for gene silencing has been reported in a bacterium other than Escherichia coli. Gene-specific silencing induced by pRNA may be useful as a novel biotechnology tool for gene regulation in prokaryotes.