Escherichia coli NsrR Regulates a Pathway for the Oxidation of 3-Nitrotyramine to 4-Hydroxy-3-Nitrophenylacetate

Abstract

Chromatin immunoprecipitation and microarray (ChIP-chip) analysis showed that the nitric oxide (NO)-sensitive repressor NsrR from Escherichia coli binds in vivo to the promoters of the tynA and feaB genes. These genes encode the first two enzymes of a pathway that is required for the catabolism of phenylethylamine (PEA) and its hydroxylated derivatives tyramine and dopamine. Deletion of nsrR caused small increases in the activities of the tynA and feaB promoters in cultures grown on PEA. Overexpression of nsrR severely retarded growth on PEA and caused a marked repression of the tynA and feaB promoters. Both the growth defect and the promoter repression were reversed in the presence of a source of NO. These results are consistent with NsrR mediating repression of the tynA and feaB genes by binding (in an NO-sensitive fashion) to the sites identified by ChIP-chip. E. coli was shown to use 3-nitrotyramine as a nitrogen source for growth, conditions which partially induce the tynA and feaB promoters. Mutation of tynA (but not feaB) prevented growth on 3-nitrotyramine. Growth yields, mutant phenotypes, and analyses of culture supernatants suggested that 3-nitrotyramine is oxidized to 4-hydroxy-3-nitrophenylacetate, with growth occurring at the expense of the amino group of 3-nitrotyramine. Accordingly, enzyme assays showed that 3-nitrotyramine and its oxidation product (4-hydroxy-3-nitrophenylacetaldehyde) could be oxidized by the enzymes encoded by tynA and feaB, respectively. The results suggest that an additional physiological role of the PEA catabolic pathway is to metabolize nitroaromatic compounds that may accumulate in cells exposed to NO.

NsrR targets in the Escherichia coli genome: new insights into DNA sequence requirements for binding and a role for NsrR in the regulation of motility

“…In an initial follow-up study, we have confirmed NsrR regulation of tynA and feaB (Rankin et al, 2008).…”

“…More likely explanations are that the repressor titration approach used was not very sensitive (see below), and/or that some NsrR targets are subject to additional layers of regulation, such that they would not be identified in a straightforward analysis of the transcriptome under a limited range of growth conditions. The latter consideration applies, for example, to the tynA and feaB genes, which were identified as potential NsrR targets by ChIP-chip (Table 2), but which are subject to regulation by NsrR only in cultures grown on unusual carbon or nitrogen sources (Rankin et al, 2008).…”

“…Genes were disrupted by replacing the coding region with a kanamycin-resistance cassette using the lred recombinase method with pKD4 as the template; mutations were converted to unmarked deletions using pCP20 (Datsenko and Wanner, 2000). The nsrR plasmid pJP07 is a derivative of p2795 (Husseiny and Hensel, 2005) and has been described previously (Rankin et al, 2008). NsrR with a C96S substitution was expressed from the equivalent plasmid pJP09.…”

Chemotaxis of Escherichia coli to Norepinephrine (NE) Requires Conversion of NE to 3,4-Dihydroxymandelic Acid

“…One pathway for NE metabolism in mammals involves deamination to form 3,4-dihydroxyphenyl-glycol-aldehyde (DOPEGAL) followed by oxidation to form 3,4-dihydroxymandelic acid (DHMA) (26). These steps in E. coli can potentially be carried out by two enzymes: a periplasmic tyramine oxidase, TynA (27), and a cytoplasmic aromatic aldehyde dehydrogenase, FeaB (27). qRT-PCR analysis showed that tynA transcription increased 4.5-fold and feaB transcription increased 3.5-fold after 1 h of incubation with 2 M NE (Fig.…”

Nitroaromatic Compounds, from Synthesis to Biodegradation

“…In rat cells, 3-nitrotyrosine is converted to 4-hydroxy-3-nitrophenylacetate through the formation of 3-nitrotyramine and 4-hydroxy-3-nitrophenylacetaldehyde intermediates (9). Escherichia coli MG1655 can use 3-nitrotyramine as a sole nitrogen source for growth but cannot use 3-nitrotyrosine (160). Similar to mammalian cells, MG1655 uses an amine oxidase (TynA) to remove the terminal amino group from 3-nitrotyramine to produce 4-hydroxy-3-nitrophenylacetaldehyde (Fig.…”