A second chromosomal copy of the catA gene endows Pseudomonas putida mt‐2 with an enzymatic safety valve for excess of catechol

Abstract

Pseudomonas putida mt-2 harbours two different routes for catabolism of catechol, namely one meta pathway encoded by the xyl genes of the TOL plasmid pWW0 and one ortho pathway determined by the chromosomal ben and cat genes. P. putida mt-2 has a second chromosomal copy of the catA gene (named catA2) located downstream of the ben operon that encodes an additional catechol-1,2-dioxygenase. The metabolic and regulatory phenotypes of strains lacking one enzyme, the other and both of them in cells with and without the TOL plasmid were evaluated. The data consistently indicated that induction of the ortho pathway by benzoate plasmid-less strain P. putida KT2440 led to catechol surplus, the toxicity of which at high concentrations being counteracted by CatA2. Cells carrying pWW0 but lacking catA2 experienced both a rapid loss of the plasmid when grown on benzoate (a substrate of the lower pathway) and a slowdown of their growth rate when cultured with benzylalcohol (a substrate converted to benzoate by the upper pathway). These data reveal the role of CatA2 as a type of metabolic safety valve for excess catechol that alleviates the metabolic conflict generated by simultaneous expression of the meta and ortho pathways, thereby facilitating their co-existence.

Hierarchy of Carbon Source Utilization in Soil Bacteria: Hegemonic Preference for Benzoate in Complex Aromatic Compound Mixtures Degraded by Cupriavidus pinatubonensis Strain JMP134

“…Phe and 2,4-D were tested at 2 mM to prevent toxic effects. Phe itself, its catabolic intermediate catechol, and the 2,4-D intermediates 2,4-dichlorophenol and chlorocatechols have been reported to be toxic through mechanisms such as oxidative phosphorylation uncoupling, enhancement of Fenton reaction, and DNA adduct formation, among others (19,(31)(32)(33)(34). Controls with the respective single AC were carried out to make proper kinetic comparisons.…”

“…1; also, see Fig. S3A in the supplemental material)-the most toxic of the intermediates generated (31,33,34)-is also produced from Phe ( Fig. 1; also, see Fig.…”

Catabolism of Phenol and Its Derivatives in Bacteria

“…TH2 and different production levels of individual paralogs were observed under various conditions (Suzuki, Ichimura, Ogawa, Hasebe, & Miyashita, 2002). Recently, the presence of a second chromosomal copy of the catA gene was found to be necessary for the survival of P. putida mt-2 under an excess of catechol (Jiménez, Pérez-Pantoja, Chavarría, Díaz, & de Lorenzo, 2014).…”

Strategy of Pseudomonas pseudoalcaligenes C70 for effective degradation of phenol and salicylate

“…Several research groups have found that bacteria possess multiple C12Os and/or C23Os [14–20]. Gene duplication seems to be a widespread phenomenon amongst TOL plasmids and gives them a selective advantage in the natural environment over those with only single copies [16].…”