Coordinated regulation of anthranilate metabolism and bacterial virulence by the GntR family regulator MpaR inPseudomonas aeruginosa

The GntR family regulators are widely distributed in bacteria and play critical roles in metabolic processes and bacterial pathogenicity. In this study, we describe a GntR family protein encoded by PA4132 that we named MpaR (MvfR-mediatedPQS andanthranilateregulator) for its regulation ofPseudomonasquinolone signal (PQS) production and anthranilate metabolism inPseudomonas aeruginosa. The deletion ofmpaRincreased biofilm formation and reduced pyocyanin production. RNA sequencing analysis revealed that the mRNA levels ofantABCencoding enzymes for the synthesis of catechol from anthranilate, a precursor of the PQS, were most affected bympaRdeletion. Data showed that MpaR directly activates the expression ofmvfR, a master regulator ofpqssystem, and subsequently promotes PQS production. Accordingly, deletion ofmpaRactivates the expression ofantABCgenes, and thus, increases catechol production. We also demonstrated that MpaR represses therhlquorum-sensing (QS) system, which has been shown to controlantABCactivity. These results suggested that MpaR function is integrated into the QS regulatory network. Moreover, mutation ofmpaRpromotes bacterial survival in a mouse model of acute pneumonia infection. Collectively, this study identified a novel regulator ofpqssystem, which coordinately controls anthranilate metabolism and bacterial virulence inP.aeruginosa.