title: Exopolyphosphatase of Pseudomonas aeruginosa is essential for the production of virulence factors, and its expression is controlled by NtrC and PhoB acting at two interspaced promoters.
abstract: The exopolyphosphatase (Ppx) of Pseudomonas aeruginosa is encoded by the PA5241 gene (ppx). Ppx catalyses the hydrolysis of inorganic polyphosphates to orthophosphate (Pi). In the present work, we identified and characterized the promoter region of ppx and its regulation under environmental stress conditions. The role of Ppx in the production of several virulence factors was demonstrated through studies performed on a ppx null mutant. We found that ppx is under the control of two interspaced promoters, dually regulated by nitrogen and phosphate limitation. Under nitrogen-limiting conditions, its expression was controlled from a σ(54)-dependent promoter activated by the response regulator NtrC. However, under Pi limitation, the expression was controlled from a σ(70) promoter, activated by PhoB. Results obtained from the ppx null mutant demonstrated that Ppx is involved in the production of virulence factors associated with both acute infection (e.g. motility-promoting factors, blue/green pigment production, C6-C12 quorum-sensing homoserine lactones) and chronic infection (e.g. rhamnolipids, biofilm formation). Molecular and physiological approaches used in this study indicated that P. aeruginosa maintains consistently proper levels of Ppx regardless of environmental conditions. The precise control of ppx expression appeared to be essential for the survival of P. aeruginosa and the occurrence of either acute or chronic infection in the host.
authors.affiliation: Departamento de Biología Molecular, FCEFQyN, Universidad Nacional de Río Cuarto, Ruta 36-Km 601, (5800) Río Cuarto, Córdoba, Argentina.
authors.forename: Lucas A
authors.initials: LA
authors.lastname: Gallarato
authors.affiliation: Departamento de Biología Molecular, FCEFQyN, Universidad Nacional de Río Cuarto, Ruta 36-Km 601, (5800) Río Cuarto, Córdoba, Argentina.
authors.forename: Diego G
authors.initials: DG
authors.lastname: Sánchez
authors.affiliation: Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210, Mexico.
authors.forename: Leticia
authors.initials: L
authors.lastname: Olvera
authors.affiliation: Departamento de Biología Molecular, FCEFQyN, Universidad Nacional de Río Cuarto, Ruta 36-Km 601, (5800) Río Cuarto, Córdoba, Argentina.
authors.forename: Emiliano D
authors.initials: ED
authors.lastname: Primo
authors.affiliation: Departamento de Biología Molecular, FCEFQyN, Universidad Nacional de Río Cuarto, Ruta 36-Km 601, (5800) Río Cuarto, Córdoba, Argentina.
authors.forename: Mónica N
authors.initials: MN
authors.lastname: Garrido
authors.affiliation: Departamento de Biología Molecular, FCEFQyN, Universidad Nacional de Río Cuarto, Ruta 36-Km 601, (5800) Río Cuarto, Córdoba, Argentina.
authors.forename: Paola R
authors.initials: PR
authors.lastname: Beassoni
authors.affiliation: Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210, Mexico.
authors.forename: Enrique
authors.initials: E
authors.lastname: Morett
authors.affiliation: Departamento de Biología Molecular, FCEFQyN, Universidad Nacional de Río Cuarto, Ruta 36-Km 601, (5800) Río Cuarto, Córdoba, Argentina.
authors.forename: Angela T
authors.initials: AT
authors.lastname: Lisa
mesh_terms: D017766:Acid Anhydride Hydrolases / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D011401:Promoter Regions, Genetic; D011550:Pseudomonas aeruginosa / Q000201:enzymology* / Q000235:genetics*; D013312:Stress, Physiological; D014157:Transcription Factors / Q000378:metabolism*; D037521:Virulence Factors / Q000378:metabolism*
chemical_list: D014157:Transcription Factors; D037521:Virulence Factors; D017766:Acid Anhydride Hydrolases; C020137:exopolyphosphatase