FIG 1.

Model of PrrF-regulated production of 2-alkyl-4-quinolones. (A) PrrF sRNAs are predicted to promote alkylquinolone production by regulating the metabolism of anthranilate. In this model, the PrrF sRNAs repress the expression of antR, encoding a LysR-type transcriptional activator that induces expression of antABC, and catBCA genes for anthranilate catabolism. This prevents the degradation of anthranilate, allowing the metabolite to instead be used for the synthesis of numerous 2-akyl-4(1H)-quinolone metabolites via the pqsABCDE, pqsH, and pqsL gene products, as previously described. R indicates the presence of an alkyl chain, which varies in length and saturation. (B) Predicted complementarity between the PrrF1 and PrrF2 sRNAs and the antR leader sequence. The numbers indicate the orientation in relation to the transcriptional start site (PrrF1 and PrrF2) or the translational start site (antR leader). The predicted start codon of the antR mRNA is underlined. The asterisks indicate the region of antR that was protected by PrrF1 in RNase protection analysis performed in the present study. Vertical lines indicate canonical base pairing. Colons indicate noncanonical (G-U) base pairing. Dashes indicate gaps in the base pairing.