Therefore, the possible catabolic repression exerted by succinate and glucose was investigated. Strains containing the reporters P paaA , P paaZ BAY 11-7082 and P paaH or the plasmid pJH1 were grown in minimal Histone Methyltransferase inhibitor medium containing PA with or without the additional carbon source and analyzed at one-hour intervals (Figure 3). B. cenocepacia K56-2 harbouring pJH1 was used as a control as the dhfr promoter is constitutive in Burkholderia species [10, 18]. Figure 3A shows that fluorescence increased linearly with optical density in the media types tested, indicating the rate of eGFP
expression does not change during growth with each of the conditions in B. cenocepacia. Initially, the levels of eGFP expression were not affected with the different carbon sources, CAL-101 concentration although at optical densities above 0.6, fluorescence varied slightly depending on the different carbon sources used. Catabolic repression by glucose on the PA-inducible eGFP expression was observed in cells harbouring P paaA , at approximately an O.D600 of 0.3 where a shift in the slope towards steady levels of fluorescence, suggesting lack of de novo eGFP synthesis, was observed (Figure 3B). The same effect was observed with reporters P paaZ and P paaH (Figure 3C and 3D respectively). This is contrasted with
cells grown in succinate, which exhibited strong silencing of eGFP expression at all cell densities (Figure 3B-D). We concluded that glucose and succinate exert catabolic repression of the PA degradation Cediranib (AZD2171) pathway. Figure 3 Phenylacetic acid genes are subject to Carbon Catabolite Repression. B. cenocepacia K56-2 containing eGFP translational fusions with the dhfr promoter (A), P paaA (B), P paaZ (C), and P paaH (D) were grown for 13 hours in M9 minimal media supplemented with the indicated carbon sources. Error bars represent the standard deviation of three independent cultures. Insertional mutagenesis of BCAL0210 results in increased expression of PA-inducible genes Located 128 bp downstream of the paaABCDE gene cluster and oriented
in the same direction are genes BCAL0211 and BCAL0210 (Figure 4A). BCAL0211 is predicted to encode a 273 amino acid protein containing a conserved domain of unknown function (DUF1835 superfamily) while BCAL0210 was annotated as a TetR family regulatory protein. Results of our BLAST search indicated the N-terminal region of BCAL0210 protein shows 60% similarity to AcrR (Expect value = 5e-7), which is a TetR-like regulator of a multi-drug efflux pump of E. coli [19–21]. Given that a regulator protein homologous to PaaX, the GntR-type transcriptional regulator of PA degradation in E. coli  is not encoded in B. cenocepacia J2315 genome, we hypothesized that the BCAL0210 gene encoded the regulator of PA catabolism in B. cenocepacia. The effect of the loss of BCAL0210 function on the regulation on the PA genes was determined by insertional mutagenesis of the BCAL0210 gene to create the strain JNRH1.