Identification and characterization of the PhhR regulon in Pseudomonas putida

Herrera, Carmen; Duque, Estrella; Rodríguez Herva, Jose Juan; Fernandez Escamilla, Ana y Ramos, Juan Luis (2010). Identification and characterization of the PhhR regulon in Pseudomonas putida. "Environmental Microbiology", v. 12 (n. 6); pp. 1427-1438. ISSN 1462-2912.


Título: Identification and characterization of the PhhR regulon in Pseudomonas putida
  • Herrera, Carmen
  • Duque, Estrella
  • Rodríguez Herva, Jose Juan
  • Fernandez Escamilla, Ana
  • Ramos, Juan Luis
Tipo de Documento: Artículo
Título de Revista/Publicación: Environmental Microbiology
Fecha: Junio 2010
Volumen: 12
Escuela: E.T.S.I. Agrónomos (UPM) [antigua denominación]
Departamento: Biotecnologia [hasta 2014]
Licencias Creative Commons: Reconocimiento - Sin obra derivada - No comercial

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Pseudomonas putida is a soil microorganism that utilizes aromatic amino acids present in root exudates as a nitrogen source. We have previously shown that the PhhR transcriptional regulator induces phhAB genes encoding a phenylalanine hydroxylase. In this study we show, using microarray assays and promoter fusions, that PhhR is a global regulator responsible for the activation of genes essential for phenylalanine degradation, phenylalanine homeostasis and other genes of unknown function. Recently, it has been shown that phenylalanine catabolism occurs through more than one pathway. One of these possible pathways involves the metabolism of phenylalanine via tyrosine, p-hydroxyphenylpyruvate, and homogentisate. We identified two genes within this pathway that encode an acyl-CoA transferase involved in the metabolism of acetoacetate. All genes in this pathway were induced in response to phenylalanine in a PhhR-proficient background. The second potential degradative pathway involves the degradation of phenylalanine to produce phenylpyruvate, which seems to be degraded via phenylacetyl-CoA. A number of mutants in the paa genes encoding phenylacetyl-CoA degradation enzymes fail to grow on phenylpyruvate or phenylacetate, further supporting the existence of this second pathway. We found that the PhhR regulon also includes genes involved in the biosynthesis of aromatic amino acids that are repressed in the presence of phenylalanine, suggesting the possibility of feedback at the transcriptional level. In addition, we found that PhhR modulates the level of expression of the broad-substrate-specificity MexEF/OprN efflux pump. Expression from this pump is under the control of mexT gene product because phenylalanine-dependent transcription from the mexE promoter does not occur in a mexT mutant background. These results place PhhR as an important regulator in the control of bacterial responses to aromatic amino acids.

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ID de Registro: 8484
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Identificador DOI: 10.1111/j.1462-2920.2009.02124.x
URL Oficial:;jsessionid=ADFA6AF069F2D94D70EDB0606A19CF6C.d01t03
Depositado por: Memoria Investigacion
Depositado el: 18 Ago 2011 09:35
Ultima Modificación: 20 Abr 2016 17:15
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