title: Finely tuned regulation of the aromatic amine degradation pathway in Escherichia coli.
abstract: FeaR is an AraC family regulator that activates transcription of the tynA and feaB genes in Escherichia coli. TynA is a periplasmic topaquinone- and copper-containing amine oxidase, and FeaB is a cytosolic NAD-linked aldehyde dehydrogenase. Phenylethylamine, tyramine, and dopamine are oxidized by TynA to the corresponding aldehydes, releasing one equivalent of H2O2 and NH3. The aldehydes can be oxidized to carboxylic acids by FeaB, and (in the case of phenylacetate) can be further degraded to enter central metabolism. Thus, phenylethylamine can be used as a carbon and nitrogen source, while tyramine and dopamine can be used only as sources of nitrogen. Using genetic, biochemical and computational approaches, we show that the FeaR binding site is a TGNCA-N8-AAA motif that occurs in 2 copies in the tynA and feaB promoters. We show that the coactivator for FeaR is the product rather than the substrate of the TynA reaction. The feaR gene is upregulated by carbon or nitrogen limitation, which we propose reflects regulation of feaR by the cyclic AMP receptor protein (CRP) and the nitrogen assimilation control protein (NAC), respectively. In carbon-limited cells grown in the presence of a TynA substrate, tynA and feaB are induced, whereas in nitrogen-limited cells, only the tynA promoter is induced. We propose that tynA and feaB expression is finely tuned to provide the FeaB activity that is required for carbon source utilization and the TynA activity required for nitrogen and carbon source utilization.
authors.affiliation: Department of Molecular and Cell Biology, The University of Texas at Dallas, Richardson, Texas, USA.
authors.forename: Ji
authors.initials: J
authors.lastname: Zeng
authors.forename: Stephen
authors.initials: S
authors.lastname: Spiro
mesh_terms: D000444:Aldehyde Dehydrogenase / Q000235:genetics / Q000378:metabolism; D000445:Aldehyde Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D006631:Amine Oxidase (Copper-Containing) / Q000235:genetics / Q000378:metabolism; D000588:Amines / Q000378:metabolism*; D001665:Binding Sites; D001711:Biotransformation; D002244:Carbon / Q000378:metabolism; D004269:DNA, Bacterial / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D006841:Hydrocarbons, Aromatic / Q000378:metabolism*; D053858:Metabolic Networks and Pathways; D008995:Monoamine Oxidase / Q000235:genetics / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D000588:Amines; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C585157:FeaR protein, E coli; D006841:Hydrocarbons, Aromatic; D015534:Trans-Activators; D014157:Transcription Factors; D002244:Carbon; D000445:Aldehyde Oxidoreductases; D000444:Aldehyde Dehydrogenase; C053855:phenylacetaldehyde dehydrogenase; D006631:Amine Oxidase (Copper-Containing); D008995:Monoamine Oxidase; C585158:TynA protein, E coli; D009584:Nitrogen