Characterization of TsaR, an oxygen-sensitive LysR-type regulator for the degradation of p-toluenesulfonate in Comamonas testosteroni T-2.
TsaR is the putative LysR-type regulator of the tsa operon (tsaMBCD) which encodes the first steps in the degradation of p-toluenesulfonate (TSA) in Comamonas testosteroni T-2. Transposon mutagenesis was used to knock out tsaR. The resulting mutant lacked the ability to grow with TSA and p-toluenecarboxylate (TCA). Reintroduction of tsaR in trans on an expression vector reconstituted growth with TSA and TCA. The tsaR gene was cloned into Escherichia coli with a C-terminal His tag and overexpressed as TsaR(His). TsaR(His) was subject to reversible inactivation by oxygen, which markedly influenced the experimental approaches used. Gel filtration showed TsaR(His) to be a monomer in solution. Overexpressed TsaR(His) bound specifically to three regions within the promoter between the divergently transcribed tsaR and tsaMBCD. The dissociation constant (K(D)) for the whole promoter region was about 0.9 micro M, and the interaction was a function of the concentration of the ligand TSA. A regulatory model for this LysR-type regulator is proposed on the basis of these data.
Tralau
Tewes
T
Department of Biology, The University of Konstanz, Germany.
Mampel
Jörg
J
Cook
Alasdair M
AM
Ruff
Jürgen
J
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001557:Benzenesulfonates / Q000378:metabolism*; D001565:Benzoates / Q000378:metabolism; D001673:Biodegradation, Environmental; D020604:Comamonas testosteroni / Q000235:genetics / Q000378:metabolism*; D004251:DNA Transposable Elements; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D010088:Oxidoreductases / Q000378:metabolism; D010100:Oxygen / Q000494:pharmacology*; D010105:Oxygenases / Q000378:metabolism; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D001426:Bacterial Proteins; D001557:Benzenesulfonates; D001565:Benzoates; D004251:DNA Transposable Elements; D014157:Transcription Factors; C104111:TsaR protein, Comamonas testosteroni; C073470:LysR protein, Bacteria; C009504:4-toluic acid; D010088:Oxidoreductases; D010105:Oxygenases; C029501:4-toluenesulfonic acid; D010100:Oxygen