New insights into the activation of o-xylene biodegradation in Pseudomonas stutzeri OX1 by pathway substrates.
The regulation of the tou operon of Pseudomonas stutzeri OX1, for degradation of toluene and o-xylene via phenolic intermediates, has been faithfully reconstructed in vitro with purified proteins. The set-up included the prokaryotic enhancer-binding protein TouR, the sigma54-dependent PToMO promoter and the sigma54-containing RNA polymerase. With this system we prove that direct binding of 2-methylphenol (o-cresol) to TouR is the only regulatory step for activation of PToMO in response to aromatic effectors, thereby ruling out the involvement of other factors or a need for protein processing. In addition, we found that while TouR failed entirely to activate PToMO in the absence of inducers, the protein had per se a very significant ATPase activity, which was only moderately increased by o-cresol addition. The results presented here support the view that TouR-like proteins are particularly suitable as evolutionary assets to endow recently evolved pathways for the degradation of environmental pollutants with an optimal degree of transcriptional regulation.
Arenghi
F L
FL
Dipartimento di Genetica e Biologia dei Microrganismi, Università degli Studi di Milano, via Celoria 26, 20133 Milan, Italy.
Barbieri
P
P
Bertoni
G
G
de Lorenzo
V
V
D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001673:Biodegradation, Environmental; D003408:Cresols / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D004268:DNA-Binding Proteins; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D005798:Genes, Bacterial; D005809:Genes, Regulator; D017930:Genes, Reporter; D011401:Promoter Regions, Genetic; D011549:Pseudomonas / Q000235:genetics* / Q000378:metabolism*; D051877:RNA Polymerase Sigma 54; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012808:Sigma Factor / Q000378:metabolism; D014158:Transcription, Genetic; D015262:Xenobiotics / Q000378:metabolism; D014992:Xylenes / Q000378:metabolism
D001426:Bacterial Proteins; D003408:Cresols; D004268:DNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D012808:Sigma Factor; D015262:Xenobiotics; D014992:Xylenes; D012321:DNA-Directed RNA Polymerases; D051877:RNA Polymerase Sigma 54; D000251:Adenosine Triphosphatases; C077977:cresol; C026114:2-xylene