Transcriptional Regulation of the Divergent paaCatabolic Operons for Phenylacetic Acid Degradation inEscherichia coli

Abstract

The expression of the divergently transcribedpaaZ and paaABCDEFGHIJK catabolic operons, which are responsible for phenylacetic acid (PA) degradation inEscherichia coli, is driven by the Pz andPa promoters, respectively. To study the transcriptional regulation of the inducible paa catabolic genes, genetic and biochemical approaches were used. Gel retardation assays showing that the PaaX regulator binds specifically to the Pa andPz promoters were complemented with in vivoexperiments that indicated a PaaX-mediated repression effect on the expression of Pa-lacZ and Pz-lacZ reporter fusions. The region within the Pa and Pz promoters that is protected by the PaaX repressor in DNase I footprinting assays contains a conserved 15-base pair imperfect palindromic sequence motif that was shown, through mutational analysis, to be indispensable for PaaX binding and repression. PA-coenzyme A (PA-CoA), but not PA, specifically inhibited binding of PaaX to the target sequences, thus confirming the first intermediate of the pathway as the true inducer and PaaX as the only bacterial regulatory protein described so far that responds to an aryl-CoA compound. Superimposed in the specific PaaX-mediated regulation is transcriptional activation by the cAMP receptor protein and the integration host factor protein. These global regulators may adjust the transcriptional output from Paand Pz promoters to the overall growth status of the cell. The expression of the divergently transcribedpaaZ and paaABCDEFGHIJK catabolic operons, which are responsible for phenylacetic acid (PA) degradation inEscherichia coli, is driven by the Pz andPa promoters, respectively. To study the transcriptional regulation of the inducible paa catabolic genes, genetic and biochemical approaches were used. Gel retardation assays showing that the PaaX regulator binds specifically to the Pa andPz promoters were complemented with in vivoexperiments that indicated a PaaX-mediated repression effect on the expression of Pa-lacZ and Pz-lacZ reporter fusions. The region within the Pa and Pz promoters that is protected by the PaaX repressor in DNase I footprinting assays contains a conserved 15-base pair imperfect palindromic sequence motif that was shown, through mutational analysis, to be indispensable for PaaX binding and repression. PA-coenzyme A (PA-CoA), but not PA, specifically inhibited binding of PaaX to the target sequences, thus confirming the first intermediate of the pathway as the true inducer and PaaX as the only bacterial regulatory protein described so far that responds to an aryl-CoA compound. Superimposed in the specific PaaX-mediated regulation is transcriptional activation by the cAMP receptor protein and the integration host factor protein. These global regulators may adjust the transcriptional output from Paand Pz promoters to the overall growth status of the cell. phenylacetic acid base pair(s) cAMP receptor protein coenzyme A integration host factor left-half operator region phenylacetyl-coenzyme A polymerase chain reaction right-half Phenylacetic acid (PA)1is a central compound to which pollutants, such as styrene andtrans-styrylacetic acid, as well as other aromatic compounds, such as 2-phenylethylamine, phenylacetaldehyde, and several phenylalkanoic acids with an even number of carbon atoms, converge through different peripheral catabolic pathways (1.Olivera E.R. Miñambres B. Garcı́a B. Muñiz C. Moreno M.A. Ferrández A. Dı́az E. Garcı́a J.L. Luengo J.M. Proc. Natl. Acad. Sci. U. S. A. 1998; 95: 6419-6424Crossref PubMed Scopus (173) Google Scholar, 2.Ferrández A. Miñambres B. Garcı́a B. Olivera E.R. Luengo J.M. Garcı́a J.L. Dı́az E. J. Biol. Chem. 1998; 273: 25974-25986Abstract Full Text Full Text PDF PubMed Scopus (172) Google Scholar). Aerobic PA catabolism in Pseudomonas putida U and Escherichia coli W has been reported to represent a novel aerobic hybrid pathway whose first step is the activation of PA to phenylacetyl-coenzyme A (PA-CoA) by the action of a PA-CoA ligase (1.Olivera E.R. Miñambres B. Garcı́a B. Muñiz C. Moreno M.A. Ferrández A. Dı́az E. Garcı́a J.L. Luengo J.M. Proc. Natl. Acad. Sci. U. S. A. 1998; 95: 6419-6424Crossref PubMed Scopus (173) Google Scholar,2.Ferrández A. Miñambres B. Garcı́a B. Olivera E.R. Luengo J.M. Garcı́a J.L. Dı́az E. J. Biol. Chem. 1998; 273: 25974-25986Abstract Full Text Full Text PDF PubMed Scopus (172) Google Scholar). In E. coli K-12 and E. coli W, thepaa genes responsible for PA catabolism are clustered in the chromosome at min 31.0 according to the E. coli K-12 linkage map (2.Ferrández A. Miñambres B. Garcı́a B. Olivera E.R. Luengo J.M. Garcı́a J.L. Dı́az E. J. Biol. Chem. 1998; 273: 25974-25986Abstract Full Text Full Text PDF PubMed Scopus (172) Google Scholar). The 14 paa genes are organized in three transcription units as follows: two divergently transcribed operons,paaZ and paaABCDEFGHIJK, encoding the catabolic genes and whose expression is driven by the Pz andPa promoters, respectively, and the paaXY operon expressing the paaX regulatory gene from the Pxpromoter (2.Ferrández A. Miñambres B. Garcı́a B. Olivera E.R. Luengo J.M. Garcı́a J.L. Dı́az E. J. Biol. Chem. 1998; 273: 25974-25986Abstract Full Text Full Text PDF PubMed Scopus (172) Google Scholar). The absence of the paa genes in E. coli W14, an E. coli W mutant strain (3.Ferrández A. Prieto M.A. Garcı́a J.L. Dı́az E. FEBS Lett. 1997; 406: 23-27Crossref PubMed Scopus (52) Google Scholar), leads to a PA− phenotype (2.Ferrández A. Miñambres B. Garcı́a B. Olivera E.R. Luengo J.M. Garcı́a J.L. Dı́az E. J. Biol. Chem. 1998; 273: 25974-25986Abstract Full Text Full Text PDF PubMed Scopus (172) Google Scholar). Previous Pa-lacZ that the Pa is by gene the absence of the a expression of the reporter (2.Ferrández A. Miñambres B. Garcı́a B. Olivera E.R. Luengo J.M. Garcı́a J.L. Dı́az E. J. Biol. Chem. 1998; 273: 25974-25986Abstract Full Text Full Text PDF PubMed Scopus (172) Google Scholar). The PaaX repressor is a acid protein that acid sequence with as B. Olivera E.R. Miñambres B. Prieto M.A. Garcı́a J.L. Luengo J.M. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google from the PA degradation pathway of putida U (1.Olivera E.R. Miñambres B. Garcı́a B. Muñiz C. Moreno M.A. Ferrández A. Dı́az E. Garcı́a J.L. Luengo J.M. Proc. Natl. Acad. Sci. U. S. A. 1998; 95: 6419-6424Crossref PubMed Scopus (173) Google and contains a of at acids that with the motif for and binding of transcriptional from the such as J. Biol. Chem. 1997; Full Text Full Text PDF PubMed Scopus Google and J. Biol. Chem. Full Text PDF PubMed Google Scholar). is that are in transcriptional regulation of aromatic catabolic operons, only a been described so far in of aromatic compounds, for the catabolism of acid in E. coli M.A. Dı́az E. Garcı́a J.L. J. PubMed Google Scholar, PubMed Scopus Google Scholar), for the catabolism of in J. 1997; PubMed Google Scholar), and for the catabolism of in S. PubMed Scopus Google Scholar). The repressor effect of PaaX on the Pa in E. coli the chromosome and the in a not be by the in the of PA, that aromatic compound is not the inducer of the pathway (2.Ferrández A. Miñambres B. Garcı́a B. Olivera E.R. Luengo J.M. Garcı́a J.L. Dı́az E. J. Biol. Chem. 1998; 273: 25974-25986Abstract Full Text Full Text PDF PubMed Scopus (172) Google Scholar). the expression of genes paaX and the encoding the PA-CoA ligase that the activation of PA to of the Pa the were in the of PA, that PA-CoA PA is the true inducer of the pathway (2.Ferrández A. Miñambres B. Garcı́a B. Olivera E.R. Luengo J.M. Garcı́a J.L. Dı́az E. J. Biol. Chem. 1998; 273: 25974-25986Abstract Full Text Full Text PDF PubMed Scopus (172) Google Scholar). to the catabolic and regulatory the PA pathway a of an aerobic hybrid for the catabolism of aromatic In in and in to the regulation of gene expression of the and paaABCDEFGHIJK catabolic from E. Superimposed in the specific PaaX-mediated two global the cAMP receptor protein and the integration host factor protein as of the gene expression driven by Pa and coli and in are in The E. coli strain was by the of E. to E. coli through PubMed Scopus Google and for a to and were in J. A at in in was at the and as carbon PA was to the were at the and and in and coli K-12 J. A PubMed Scopus Google PubMed Scopus Google J. PubMed Google J. PubMed Google J. PubMed Google M.A. Garcı́a J.L. 1997; PubMed Scopus Google M.A. Garcı́a J.L. 1997; PubMed Scopus Google PubMed Scopus Google mutant mutant mutant mutant mutant with with with with with with with with with with coli W A. Prieto M.A. Garcı́a J.L. Dı́az E. FEBS Lett. 1997; 406: 23-27Crossref PubMed Scopus (52) Google mutant A. Miñambres B. Garcı́a B. Olivera E.R. Luengo J.M. Garcı́a J.L. Dı́az E. J. Biol. Chem. 1998; 273: 25974-25986Abstract Full Text Full Text PDF PubMed Scopus (172) Google with PubMed Scopus Google by A. Miñambres B. Garcı́a B. Olivera E.R. Luengo J.M. Garcı́a J.L. Dı́az E. J. Biol. Chem. 1998; 273: 25974-25986Abstract Full Text Full Text PDF PubMed Scopus (172) Google a to A. Miñambres B. Garcı́a B. Olivera E.R. Luengo J.M. Garcı́a J.L. Dı́az E. J. Biol. Chem. 1998; 273: 25974-25986Abstract Full Text Full Text PDF PubMed Scopus (172) Google the Pz-lacZ from the A. Miñambres B. Garcı́a B. Olivera E.R. Luengo J.M. Garcı́a J.L. Dı́az E. J. Biol. Chem. 1998; 273: 25974-25986Abstract Full Text Full Text PDF PubMed Scopus (172) Google number A. Miñambres B. Garcı́a B. Olivera E.R. Luengo J.M. Garcı́a J.L. Dı́az E. J. Biol. Chem. 1998; 273: 25974-25986Abstract Full Text Full Text PDF PubMed Scopus (172) Google a the paa A. Miñambres B. Garcı́a B. Olivera E.R. Luengo J.M. Garcı́a J.L. Dı́az E. J. Biol. Chem. 1998; 273: 25974-25986Abstract Full Text Full Text PDF PubMed Scopus (172) Google number the gene A. Miñambres B. Garcı́a B. Olivera E.R. Luengo J.M. Garcı́a J.L. Dı́az E. J. Biol. Chem. 1998; 273: 25974-25986Abstract Full Text Full Text PDF PubMed Scopus (172) Google number J. A expressing the paaX gene A. Miñambres B. Garcı́a B. Olivera E.R. Luengo J.M. Garcı́a J.L. Dı́az E. J. Biol. Chem. 1998; 273: 25974-25986Abstract Full Text Full Text PDF PubMed Scopus (172) Google expressing the paaX gene A. Miñambres B. Garcı́a B. Olivera E.R. Luengo J.M. Garcı́a J.L. Dı́az E. J. Biol. 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Chem. 1998; 273: 25974-25986Abstract Full Text Full Text PDF PubMed Scopus (172) Google Scholar), are the that a and the which and the transcription of Pa (2.Ferrández A. Miñambres B. Garcı́a B. Olivera E.R. Luengo J.M. Garcı́a J.L. Dı́az E. J. Biol. Chem. 1998; 273: 25974-25986Abstract Full Text Full Text PDF PubMed Scopus (172) Google Scholar), is is A and W is A and and Pa promoters, of the paa gene (2.Ferrández A. Miñambres B. Garcı́a B. Olivera E.R. Luengo J.M. Garcı́a J.L. Dı́az E. J. Biol. Chem. 1998; 273: 25974-25986Abstract Full Text Full Text PDF PubMed Scopus (172) Google the is and the which is to the The two were and to a reaction and as to in the right-half of the PaaX binding a first reaction was two of and the which and the transcription (2.Ferrández A. Miñambres B. Garcı́a B. Olivera E.R. Luengo J.M. Garcı́a J.L. Dı́az E. J. Biol. Chem. 1998; 273: 25974-25986Abstract Full Text Full Text PDF PubMed Scopus (172) Google Scholar), and and the which is to the The two were and to a reaction and as The were with and and as the to the which were to the sequence of the mutant of and which hybrid expressing Pz-lacZ respectively, were coli different coli and as described PubMed Scopus Google Scholar). the the chromosome were for the on The and and are indicated in The paaX gene was from the in the number and in the number of coli not the of an to the PaaX protein were with from the thus that the paaX gene was not in To the PaaX E. coli were in to of were min at and were and in of and to by through a at a of The was by at for min at The was and as The from E. coli were in a was by the of PubMed Scopus Google as The target as were by as To the which acids of and with the of gene and of thepaa gene (2.Ferrández A. Miñambres B. Garcı́a B. Olivera E.R. Luengo J.M. Garcı́a J.L. Dı́az E. J. Biol. Chem. 1998; 273: 25974-25986Abstract Full Text Full Text PDF PubMed Scopus (172) Google and were used. To the Pa and were used. To the Pz which and of region (2.Ferrández A. Miñambres B. Garcı́a B. Olivera E.R. Luengo J.M. Garcı́a J.L. Dı́az E. J. Biol. Chem. 1998; 273: 25974-25986Abstract Full Text Full Text PDF PubMed Scopus (172) Google Scholar), and were used. The in the PaaX binding motif were from the of and which acids of and with the of the gene and (2.Ferrández A. Miñambres B. Garcı́a B. Olivera E.R. Luengo J.M. Garcı́a J.L. Dı́az E. J. Biol. Chem. 1998; 273: 25974-25986Abstract Full Text Full Text PDF PubMed Scopus (172) Google The and were to the from the as were at with and The reaction and in a and were by S. and A. respectively. for min at were by in with The were and to of the were in a and the of the and was the The of PaaX for the was as the of protein of reaction at which of the to be as were by a the The was with were in a and the was with of To the of the and were used. The was in a and through the DNase I footprinting the reaction and in a was for min at which of DNase I at in was and the was for min at was to the to a of and were with with and in of were at for min and in a A and A PubMed Scopus Google were with the and in the with the footprinting The were and to were with as described by in Scholar). that the Pa which the expression of the paaABCDEFGHIJK catabolic is by the PaaX regulator (2.Ferrández A. Miñambres B. Garcı́a B. Olivera E.R. Luengo J.M. Garcı́a J.L. Dı́az E. J. Biol. Chem. 1998; 273: 25974-25986Abstract Full Text Full Text PDF PubMed Scopus (172) Google Scholar). To the expression of the divergently transcribed Pz which the expression of the catabolic was by a reporter Pz-lacZ within a The was to by the Pz-lacZ the chromosome of E. coli a of E. coli to the reporter strain E. coli The assays of coli the a that the encoding the PA-CoA a and expression of the Pz-lacZ the paaX gene was in from the in E. coli in in the in the absence of PA, was and genes were in the reporter was the were in the of PA, and was in the absence of aromatic compound These that PaaX as a transcriptional repressor of Pz and that the of the reaction by is the true inducer of of expression from the Pz by coli different were in in the absence in the of PA, the of were with as described of are were in three in a E. coli different were in in the absence in the of PA, the of were with as described of are were in three from E. coli a strain that the paaX gene the were to retardation as a the Pz and Pa promoters in PaaX were to the of the in a protein from E. coli a of an such as that of not the binding of PaaX to the target of the was not a of was to the not that binding of the PaaX repressor to region was the of PaaX protein two and were a that that PaaX binds with different to two in the as To the of two different retardation assays were the Pz to to the transcription of Pz and the Pa to to the transcription of Pa as in was with the of PaaX for the Pa and Pz and respectively, were to that for and with the is in the binding of PaaX to the Pa andPz the specific and binding of PaaX to the Pa that the expression driven by the Pa (2.Ferrández A. Miñambres B. Garcı́a B. Olivera E.R. Luengo J.M. Garcı́a J.L. Dı́az E. J. Biol. Chem. 1998; 273: 25974-25986Abstract Full Text Full Text PDF PubMed Scopus (172) Google and Pz promoters in the paaX gene in a the expression of the gene encoding the PA-CoA ligase as well as the of PA in the has to the that the true inducer of thepaa catabolic is PA-CoA been to a in the of such as chain acids A. PubMed Scopus Google Scholar), not the that E. the gene in PA that to paa by retardation assays the of PA and PA-CoA to binding of PaaX to the region in PA-CoA the of to PA not the binding even compound was to a of not A of PA-CoA such as effect on binding to the retardation to a of not such as and were to binding of PaaX to the Pa not thus confirming PA-CoA as the specific inducer of thepaa catabolic To the PaaX binding region within the Pa and DNase I footprinting were the target as in the retardation assays reported in an binding region was in The footprinting with the of the Pa a protected operator region A and with to the transcription of that the of the gene the other the of the Pz was protected by PaaX from DNase I and operator region the of the of DNase I for of the were A and The DNase in and were at to and which binding of PaaX to of the of the PaaX binding by DNase I footprinting that of the operator in Pa and in a conserved imperfect palindromic motif the conserved motif in is and that of is and of the A palindromic sequence was to be is A W is A and is with through the central base which a left-half and a right-half with within the operator are the binding of bacterial transcriptional regulators PubMed Scopus Google Scholar), that the described conserved be the binding of PaaX within and To the of the conserved motif in the and binding of PaaX to base in the target motif were by and the and mutant Pa were to the of the as indicated the of E. coli expressing the were to that of expressing the different mutant Pa-lacZ the that in the of be The binding of PaaX to the different was in by in E. coli expressing paaX and the different fusions. in base in the region of the conserved mutant and the PaaX-mediated repression of the as with the the in repression was with mutant promoters and two base with mutant and only base in the region of the conserved mutant promoters not a in PaaX-mediated repression as as that with base in the of the conserved at of the mutant to a in repression with that with the Pa and the two base in mutant promoters the repression effect of PaaX on the repression on different Pa-lacZ reporter coli which contains the Pa-lacZ the different which to the promoters indicated in and the the were at in to an A of were with as described of are were in three in a E. coli which contains the Pa-lacZ the different which to the promoters indicated in and the the were at in to an A of were with as described of are were in three The of the base on binding of PaaX to were in by the and the different mutant Pa as in retardation in the region of the conserved motif promoters the binding of PaaX to the mutant promoters as with that for the in the region and not The of PaaX for the mutant was that for the other two promoters in the and but that for the promoters in the region These in are in with the in reported the fusions. that the conserved motif in the Pa andPz promoters is for PaaX repressor with the region of the motif for repressor binding the The mutant which in to a base at the of a of the region to a in repression and to a in PaaX binding as with the Pa that the conserved motif may the repressor effect of PaaX on the expression of the paa catabolic of the region the of two sequences, and from to and to to the transcription of that the W is A is A and is of the and for binding to the PubMed Scopus Google and J. J.L. B. Escherichia coli and and for global regulators PubMed Scopus Google Scholar), respectively. To the of and in paa genetic and biochemical of E. coli and coli which with the Pa andPz promoters of and respectively, were in in the of were in in the of PA, was thus a repression effect on Pa and Pz by To the regulation by was by and Pz-lacZ were the chromosome of an E. coli as described was in the and the were in in the of the Pa and to be by the which repression by reported To genetic retardation assays were with in the of cAMP and three different and as in a was with the and the Pa binding of to the Pz was These are in with the that a is in the region but to the Pa to transcriptional To study the on the expression of the genes, the Pa-lacZ and were the chromosome of E. coli and and the two of the as described The were in in the of PA, and the effect on the driven by the Pa and Pz promoters was by in was a of Pa and Pz in the and with the in the and To the in from the Pa and was to the binding of regulator to such promoters, retardation assays were was to to the binding to the Pa was the of with the region was specific a of the of the but an of Pa In genetic and biochemical approaches to study the regulation of the expression of the divergently transcribed and paaABCDEFGHIJK catabolic responsible for PA catabolism in E. that the PaaX protein as a transcriptional repressor of the Pa (2.Ferrández A. Miñambres B. Garcı́a B. Olivera E.R. Luengo J.M. Garcı́a J.L. Dı́az E. J. Biol. Chem. 1998; 273: 25974-25986Abstract Full Text Full Text PDF PubMed Scopus (172) Google Scholar). a genetic on has that PaaX as a repressor of the Pz The of the retardation assays indicated that the PaaX repressor binds specifically and to of and Pz promoters, the binding of PaaX for Pa was that DNase I footprinting that PaaX protected an region of that is of the transcription within the and that the and the region in the Pz is that the effect of the PaaX protein on the Pa andPz promoters different of of and a at the of the which was by to be indispensable for binding of PaaX to The of the and the that the is by a acid of PaaX (2.Ferrández A. Miñambres B. Garcı́a B. Olivera E.R. Luengo J.M. Garcı́a J.L. Dı́az E. J. Biol. Chem. 1998; 273: 25974-25986Abstract Full Text Full Text PDF PubMed Scopus (172) Google Scholar), that to that of transcriptional of the J. Biol. Chem. 1997; Full Text Full Text PDF PubMed Scopus Google Scholar, J. Biol. Chem. Full Text PDF PubMed Google that the regulator is in an to The two sequence of the PaaX binding motif are by a through the central base at the region of the PaaX binding motif is conserved in the operator of other bacterial regulators such as J. Biol. Chem. Full Text PDF PubMed Google and M.A. PubMed Scopus Google to the J. J.L. B. Escherichia coli and and for Scholar, A. S. S. S. PubMed Google and J. Biol. PubMed Scopus Google to the the region from that of other the of the region in is in the region of the and has been to a in binding to the regulators A. S. S. S. PubMed Google Scholar, J.L. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar). In that in the region of are for PaaX binding and repression in in the that the repressor different of with the two of the binding and the are with the been within the the region the is the for the with the repressor J.L. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar). The DNase in the region of and a of the by the PaaX a that has been reported for other operator J.L. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar). the conserved PaaX binding motif is for PaaX such as that of the mutant to the of the repressor for the showing that to the regulator binding to the with the been reported for other regulators A. S. S. S. PubMed Google Scholar, J. Biol. PubMed Scopus Google Scholar, J. Biol. PubMed Scopus Google Scholar). of the gene expression driven by the Pa (2.Ferrández A. Miñambres B. Garcı́a B. Olivera E.R. Luengo J.M. Garcı́a J.L. Dı́az E. J. Biol. Chem. 1998; 273: 25974-25986Abstract Full Text Full Text PDF PubMed Scopus (172) Google and Pz promoters PA and a PA-CoA was to that the true inducer of the paa catabolic was the first intermediate of the the was in through retardation assays which that binding of PaaX to the Pa and Pz promoters is specifically by PA-CoA and not by PA To the E. coli which the expression of genes in acid and was the only regulator for which is that of with the protein binding J. J. Biol. Chem. 1998; 273: Full Text Full Text PDF PubMed Scopus Google Scholar). The PaaX repressor the first of a regulator protein that responds specifically to an aryl-CoA compound. is that other regulatory showing a acid sequence with the repressor of the PA degradation pathway from putida U (1.Olivera E.R. Miñambres B. Garcı́a B. Muñiz C. Moreno M.A. Ferrández A. Dı́az E. Garcı́a J.L. Luengo J.M. Proc. Natl. Acad. Sci. U. S. A. 1998; 95: 6419-6424Crossref PubMed Scopus (173) Google Scholar), the of a PA catabolic pathway from number and the repressor number of the pathway of in A. J. E. PubMed Google Scholar), with aryl-CoA In to the regulation by the PaaX the paa catabolic of E. to by the two global J. J.L. B. Escherichia coli and and for and PubMed Scopus Google Scholar). that E. to the Pa-lacZ and that as an of the gene expression driven by the Pa and Gel retardation assays the binding of the to the Pa region a was at with to the transcription of Pa a activation to that described for I promoters S. J. Biol. PubMed Scopus Google Scholar). is for of the binding of to the Pz was in retardation assays that to to the Pz the is at with to the transcription of Pz far to transcription from C. PubMed Scopus Google Scholar), transcription may be that binds to the region and transcription from the Pa and Pz promoters sequence a within the Pz at with to the transcription of Pa of the region polymerase to Pz and be an that to be repression has been described for the degradation of aromatic in different 1998; PubMed Scopus Google Scholar). that E. coli are in in the of carbon gene expression from the Pa andPz promoters is to carbon repression. In to the in Pseudomonas and other the of repression is not 1998; PubMed Scopus Google Scholar, E. S. B. Pseudomonas and for Scholar), the effect of in E. coli is through the action of J. J.L. B. Escherichia coli and and for Scholar, A. S. S. S. PubMed Google Scholar). A repression effect of by the was in E. coli for the catabolism of other aromatic such as J. PubMed Google and acid M.A. Garcı́a J.L. 1997; PubMed Scopus Google Scholar), and is to for acid degradation M.A. Dı́az E. Garcı́a J.L. J. PubMed Google Scholar, PubMed Scopus Google Scholar). the catabolism of PA in putida U is catabolic repression by (1.Olivera E.R. Miñambres B. Garcı́a B. Muñiz C. Moreno M.A. Ferrández A. Dı́az E. Garcı́a J.L. Luengo J.M. Proc. Natl. Acad. Sci. U. S. A. 1998; 95: 6419-6424Crossref PubMed Scopus (173) Google Scholar). is well that promoters are to of which adjust transcriptional output to the of the 1998; PubMed Scopus Google Scholar). in that the specific PaaX-mediated of the Pa and Pz promoters for PA degradation in E. coli in to a regulation by global regulators such as and which the expression of the paa catabolic genes to the and status of the cell. B. for strain for and and J. Luengo for the are to S. and A. for the of and respectively. the of E. with A. and S. with and the of E. and and C. for with the retardation and footprinting are to for the and to A. Prieto and C. for the of the