Identification of GntR as regulator of the glucose metabolism in Pseudomonas aeruginosa

Abstract

In contrast to Escherichia coli, glucose metabolism in pseudomonads occurs exclusively through the Entner-Doudoroff (ED) pathway. This pathway, as well as the three routes to generate the initial ED pathway substrate, 6-phosphogluconate, is regulated by the PtxS, HexR and GtrS/GltR systems. With GntR (PA2320) we report here the identification of an additional regulator in Pseudomonas aeruginosa PAO1. GntR repressed its own expression as well as that of the GntP gluconate permease. In contrast to PtxS and GtrS/GltR, GntR did not modulate expression of the toxA gene encoding the exotoxin A virulence factor. GntR was found to bind to promoters P and P and the consensus sequence of its operator was defined as 5'-AC-N-AAG-N-TAGCGCT-3'. Both operator sites overlapped with the RNA polymerase binding site and we show that GntR employs an effector mediated de-repression mechanism. The release of promoter bound GntR is induced by gluconate and 6-phosphogluconate that bind with similar apparent affinities to the GntR/DNA complex. GntR and PtxS are paralogous and may have evolved from a common ancestor. The concerted action of four regulatory systems in the regulation of glucose metabolism in Pseudomonas can be considered as a model to understand complex regulatory circuits in bacteria.

Regulation of carbohydrate degradation pathways in Pseudomonas involves a versatile set of transcriptional regulators

“…As has been mentioned by Daddaoua et al . (), the inspection of the genetic context of genes involved in glucose metabolism in P. aeruginosa resulted in the detection of a GntR‐like transcriptional regulator (Jain, ), that is predicted to possess an N‐terminal HTH DNA‐binding motif and a periplasmic binding protein‐like domain for effector binding (Daddaoua et al ., ). In P. aeruginosa , it was found that the gntR gene is transcribed divergently to the gnuK gene (gluconokinase), which is located adjacent to those of the gluconate transporter (GntP) and a glyceraldehyde‐3‐phosphate dehydrogenase (GapN) (Fig.…”

“…In P. aeruginosa, it was found that the gntR gene is transcribed divergently to the gnuK gene (gluconokinase), which is located adjacent to those of the gluconate transporter (GntP) and a glyceraldehyde-3-phosphate dehydrogenase (GapN) (Fig. 2) It has been proposed that GntR regulates its own expression, as well as that of a gluconokinase (GnuK), gluconate permease (GntP) and gluconate 6phosphate dehydrogenase (GntZ) gene (Daddaoua et al, 2017;Del Castillo et al, 2007).…”

“…4) because the release of promoter-bound GntR is induced by gluconate and 6-phosphogluconate that bind with similar apparent affinities to the GntR/DNA complex (Table 2). Surprisingly, GntR and PtxS are paralogous which may have evolved from a common ancestor (Daddaoua et al, 2017).…”

“…In addition, there is evidence for TCS that contains additional signalling proteins (Mitchell et al, 2015;Popella et al, 2016). Data so far available indicate that the regulation of the glucose catabolic pathways in Pseudomonas is controlled by the concerted action of the one-component systems (OCSs) HexR, PtxS, PtxR and GntR as well as the two-component system (TCS) GltR/GtrS (Daddaoua et al, 2009(Daddaoua et al, , 2012(Daddaoua et al, , 2014(Daddaoua et al, , 2017. This review focuses on the description of this regulatory network and highlights a number of differences in regulation between strains of the soil bacterium P. putida and the opportunistic human pathogen Pseudomonas aeruginosa.…”

Pseudomonas syringaedual‐function protein Lon switches between virulence and metabolism by acting as bothDNA‐binding transcriptional regulator and protease in different environments

“…Lon negatively regulated the gluconate kinase activity by binding to the gntR promoter in KB Based on the ChIP-seq results, we performed an EMSA and verified the direct interaction between Lon and the promoter of gntR (−95 to +55 from ATG), which encodes a transcriptional repressor involved in glucose metabolism ( Fig. 4H; Daddaoua et al, 2017;Udaondo et al, 2018). In KB, the expression level of gntR was approximately twofold lower in the Δlon strain than in the WT, whereas no significant difference was observed in MM ( Fig.…”