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Título

The homogentisate pathway: a central catabolic pathway involved in the degradation of L-phenylalanine, L-tyrosine, and 3-hydroxyphenylacetate in Pseudomonas putida

AutorArias-Barrau, Elsa; Olivera, Elías R.; Luengo, José M.; Fernández, Cristina; Galán, Beatriz ; García, José Luis ; Díaz, Eduardo ; Miñambres Rodríguez, Baltasar
Palabras claveGram-negative bacteria
Phenylacetyl-coa catabolon
Complete genome sequence
Escherichia-coli
4-Hydroxyphenylpyruvate dioxygenase
Molecular characterization
Transcriptional regulator
Hereditary tyrosinemia
Aspergillus-nidulans
P-Hydroxybenzoate
Fecha de publicación2004
EditorAmerican Society for Microbiology
CitaciónJournal of Bacteriology 186(15): 5062-5077 (2004)
ResumenPseudomonas putida metabolizes Phe and Tyr through a peripheral pathway involving hydroxylation of Phe to Tyr (PhhAB), conversion of Tyr into 4-hydroxyphenylpyruvate (TyrB), and formation of homogentisate (Hpd) as the central intermediate. Homogentisate is then catabolized by a central catabolic pathway that involves three enzymes, homogentisate dioxygenase (HmgA), fumarylacetoacetate hydrolase (HmgB), and maleylacetoacetate isomerase (HmgC), finally yielding fumarate and acetoacetate. Whereas the phh, tyr, and hpd genes are not linked in the P. putida genome, the hmgABC genes appear to form a single transcriptional unit. Gel retardation assays and lacZ translational fusion experiments have shown that hmgR encodes a specific repressor that controls the inducible expression of the divergently transcribed hmgABC catabolic genes, and homogentisate is the inducer molecule. Footprinting analysis revealed that HmgR protects a region in the Phmg promoter that spans a 17-bp palindromic motif and an external direct repetition from position -16 to position 29 with respect to the transcription start site. The HmgR protein is thus the first IcIR-type regulator that acts as a repressor of an aromatic catabolic pathway. We engineered a broad-host-range mobilizable catabolic cassette harboring the hmgABC, hpd, and tyrB genes that allows heterologous bacteria to use Tyr as a unique carbon and energy source. Remarkably, we show here that the catabolism of 3-hydroxyphenylacetate in P. putida U funnels also into the homogentisate central pathway, revealing that the hmg cluster is a key catabolic trait for biodegradation of a small number of aromatic compounds.
Descripción16 pages, 3 tables, 11 figures.-- PMID: 15262943 [PubMed].-- PMCID: PMC451635.
Versión del editorhttp://dx.doi.org/10.1128/JB.186.15.5062-5077.2004
URIhttp://hdl.handle.net/10261/12021
DOI10.1128/JB.186.15.5062-5077.2004
ISSN0021-9193
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