Less is more: reduced catechol production permits Pseudomonas putida F1 to grow on styrene.
Pseudomonas putida F1 is unable to grow on styrene due to the accumulation of 3-vinylcatechol, a toxic metabolite that is produced through the toluene degradation (tod) pathway and causes catechol-2,3-dioxygenase (C23O) inactivation. In this study, we characterized a spontaneous F1 mutant, designated SF1, which acquired the ability to grow on styrene and did not accumulate 3-vinylcatechol. Whereas adaptation to new aromatic substrates has typically been shown to involve increased C23O activity or the acquisition of resistance to C23O inactivation, SF1 retained wild-type C23O activity. Surprisingly, SF1 grew more slowly on toluene, its native substrate, and exhibited reduced toluene dioxygenase (TDO) activity (approximately 50 % of that of F1), the enzyme responsible for ring hydroxylation and subsequent production of 3-vinylcatechol. DNA sequence analysis of the tod operon of SF1 revealed a single base pair mutation in todA (C479T), a gene encoding the reductase component of TDO. Replacement of the wild-type todA allele in F1 with todA(C479T) reduced TDO activity to SF1 levels, obviated vinylcatechol accumulation, and conferred the ability to grow on styrene. This novel 'less is more' strategy - reduced catechol production as a means to expand growth substrate range - sheds light on an alternative approach for managing catechol toxicity during the metabolism of aromatic compounds.
Field of Environmental Toxicology, Cornell University, Ithaca, NY 14850, USA.
Kevin W
KW
George
Department of Microbiology, Cornell University, Ithaca, NY 14850, USA.|Field of Environmental Toxicology, Cornell University, Ithaca, NY 14850, USA.
Anthony
A
Hay
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D050557:Catechol 2,3-Dioxygenase / Q000235:genetics / Q000378:metabolism; D002396:Catechols / Q000378:metabolism*; D009154:Mutation; D010105:Oxygenases / Q000235:genetics / Q000378:metabolism; D016958:Pseudomonas putida / Q000201:enzymology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D020058:Styrene / Q000378:metabolism*; D014050:Toluene / Q000378:metabolism
D001426:Bacterial Proteins; D002396:Catechols; D014050:Toluene; D020058:Styrene; D010105:Oxygenases; D050557:Catechol 2,3-Dioxygenase; C023172:toluene dioxygenase; C034221:catechol