GtrS and GltR form a two-component system: the central role of 2-ketogluconate in the expression of exotoxin A and glucose catabolic enzymes in Pseudomonas aeruginosa

Nucleic Acids Res. 2014 Jul;42(12):7654-63. doi: 10.1093/nar/gku496. Epub 2014 Jun 11.


In the human pathogen Pseudomonas aeruginosa, the GltR regulator is required for glucose transport, whereas GtrS is a sensor kinase that plays a key role in mediating bacteria-host interaction and pathogen dissemination in the host. We show that GtrS and GltR form a two-component system that regulates the expression from the promoters Pedd/gap-1, PoprB and Pglk, which control the expression of genes involved in glucose metabolism and transport. In addition, the GtrS/GltR pair regulates the expression of toxA that encodes exotoxin A, the primary virulence factor. Microcalorimetry-based ligand screening of the recombinant GtrS ligand-binding domain revealed specific binding of 2-ketogluconate (2-KG) (KD=5 μM) and 6-phosphogluconate (KD=98 μM). These effectors accelerate GtrS autophosphorylation, with concomitant transphosphorylation of GltR leading to a three-fold increase in transcription. Surprisingly, in vivo a similar increase in expression from the above promoters was observed for the mutant deficient in GltR regardless of the presence of effectors. The GltR operator site was found to contain the consensus sequence 5'-tgGTTTTTc-3'. We propose that 2-KG is a key metabolite in the stringent transcriptional control of genes involved in virulence and glucose metabolism. We show that GltR is a transcriptional repressor that is released from DNA upon phosphorylation.

MeSH terms

  • ADP Ribose Transferases / genetics*
  • ADP Ribose Transferases / metabolism
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / metabolism*
  • Bacterial Toxins / genetics*
  • Bacterial Toxins / metabolism
  • Binding Sites
  • Exotoxins / genetics*
  • Exotoxins / metabolism
  • Gene Expression Regulation, Bacterial*
  • Gluconates / metabolism*
  • Glucose / metabolism*
  • Monosaccharide Transport Proteins / metabolism*
  • Promoter Regions, Genetic
  • Protein Kinases / metabolism*
  • Protein Structure, Tertiary
  • Pseudomonas aeruginosa / enzymology
  • Pseudomonas aeruginosa / genetics*
  • Pseudomonas aeruginosa / metabolism
  • Repressor Proteins / metabolism
  • Transcriptional Activation
  • Virulence Factors / genetics*
  • Virulence Factors / metabolism


  • Bacterial Proteins
  • Bacterial Toxins
  • Exotoxins
  • GltR protein, Pseudomonas aeruginosa
  • Gluconates
  • Monosaccharide Transport Proteins
  • Repressor Proteins
  • Virulence Factors
  • 2-ketogluconate
  • ADP Ribose Transferases
  • Pseudomonas aeruginosa exotoxin A
  • Protein Kinases
  • Glucose
  • 6-phosphogluconic acid