title: 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.
abstract: 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.
authors.affiliation: Department of Environmental Protection, CSIC-EEZ, C/Profesor Albareda 1, E-18008 Granada, Spain abdelali.daddaoua@eez.csic.es.
authors.forename: Abdelali
authors.initials: A
authors.lastname: Daddaoua
authors.affiliation: Department of Environmental Protection, CSIC-EEZ, C/Profesor Albareda 1, E-18008 Granada, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Molina-Santiago
authors.affiliation: Department of Environmental Protection, CSIC-EEZ, C/Profesor Albareda 1, E-18008 Granada, Spain.
authors.forename: Jesús
authors.initials: J
authors.lastname: de la Torre
authors.affiliation: Department of Environmental Protection, CSIC-EEZ, C/Profesor Albareda 1, E-18008 Granada, Spain.
authors.forename: Tino
authors.initials: T
authors.lastname: Krell
authors.affiliation: Department of Environmental Protection, CSIC-EEZ, C/Profesor Albareda 1, E-18008 Granada, Spain.
authors.forename: Juan-Luis
authors.initials: JL
authors.lastname: Ramos
mesh_terms: D036002:ADP Ribose Transferases / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D001427:Bacterial Toxins / Q000235:genetics* / Q000378:metabolism; D001665:Binding Sites; D005098:Exotoxins / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D005942:Gluconates / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D009004:Monosaccharide Transport Proteins / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011494:Protein Kinases / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D011550:Pseudomonas aeruginosa / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism; D015533:Transcriptional Activation; D037521:Virulence Factors / Q000235:genetics* / Q000378:metabolism; D000097668:Pseudomonas aeruginosa Exotoxin A
chemical_list: D036002:ADP Ribose Transferases; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D005098:Exotoxins; D005942:Gluconates; D005947:Glucose; D009004:Monosaccharide Transport Proteins; D011494:Protein Kinases; D012097:Repressor Proteins; D037521:Virulence Factors; D000097668:Pseudomonas aeruginosa Exotoxin A; C101962:GltR protein, Pseudomonas aeruginosa; C008229:2-ketogluconate; C008884:6-phosphogluconic acid