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Effect of aminoglycoside resistance RmtD methyltransferase on biofilm formation and pyocyanin production in Pseudomonas aeruginosa PAO1

Pseudomonas aeruginosa is one of the leading causes of life-threatening nosocomial infections. The problem of antibiotic resistance is highlighted by the emergence of multi-drug resistant strains. One of the pathogenic potential of P. aeruginosa is based on formation of biofilm during chronic infections. The regulation of many virulence associated factors, such as pyocyanin production and biofilm formation in P. aeruginosa, is under the control of quorum sensing (QS) system. RmtD is a methyltransferase that confers resistance to aminoglycosides, and was identified in an P. aeruginosa clinical isolate. In this study, we demonstrate that 16S rRNA methyltransferase RmtD positively affects the formation of biofilm, and swarming motility. In order to link RmtD with the elements of quorum sensing systems, in particular with Pseudomonas quinolone signal (PQS), we constructed a P. aeruginosa pqsA mutant and demonstrated that RmtD negatively affects biofilm formation in the absence of PQS system. To address the effect of RmtD on the expression of different P. aeruginosa QS genes within each system, we analyzed transcript levels using qRT-PCR. The results suggest that RmtD differentially influenced the expression of QS genes (lasI, rhlI, gacA, pqsE, phzC1), additionally suggesting that RmtD modulates the expression of quorum sensing in P. aeruginosa. Further studies will address the mechanism linking 16S rRNA methyltransferase RmtD and quorum sensing in P. aeruginosa.

Pseudomonas aeruginosa PA01; 16S rRNA methyltransferase RmtD; biofilm; quorum sensing

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