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Unravelling the gallic acid degradation pathway in bacteria: the gal cluster from Pseudomonas putida
Author(s) -
Nogales Juan,
Canales Ángeles,
JiménezBarbero Jesús,
Serra Beatriz,
Pingarrón José Manuel,
García José Luis,
Díaz Eduardo
Publication year - 2011
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2010.07448.x
Subject(s) - pseudomonas putida , biology , biochemistry , gallic acid , bacteria , aldolase a , dioxygenase , pseudomonas , gene , enzyme , microbiology and biotechnology , genetics , antioxidant
Summary Gallic acid (3,4,5‐trihydroxybenzoic acid, GA) is widely distributed in nature, being a major phenolic pollutant and a commonly used antioxidant and building‐block for drug development. We have characterized the first complete cluster ( gal genes) responsible for growth in GA in a derivative of the model bacterium Pseudomonas putida KT2440. GalT mediates specific GA uptake and chemotaxis, and highlights the critical role of GA transport in bacterial adaptation to GA consumption. The proposed GA degradation via the central intermediate 4‐oxalomesaconic acid (OMA) was revisited and all enzymes involved have been identified. Thus, GalD is the prototype of a new subfamily of isomerases that catalyses a biochemical step that remained unknown, i.e. the tautomerization of the OMAketo generated by the GalA dioxygenase to OMAenol. GalB is the founding member of a new family of zinc‐containing hydratases that converts OMAenol into 4‐carboxy‐4‐hydroxy‐2‐oxoadipic acid (CHA). galC encodes the aldolase catalysing CHA cleavage to pyruvic and oxaloacetic acids. The presence of homologous gal clusters outside the Pseudomonas genus sheds light on the evolution and ecology of the gal genes in GA degraders. The gal genes were used for expanding the metabolic abilities of heterologous hosts towards GA degradation, and for engineering a GA cellular biosensor.