title: FNR-dependent repression of the ndh gene of Escherichia coli and metal ion requirement for FNR-regulated gene expression.
abstract: The ndh gene of Escherichia coli which encodes an NADH dehydrogenase contains a putative FNR-binding site in its upstream non-coding region, and its expression has been investigated using an ndh-lacZ fusion. Expression of the fusion was found to be reduced during anaerobic growth, and experiments with hosts containing an fnr mutation and/or a multicopy fnr+ plasmid indicated that the anaerobic repression of the ndh gene is mediated by the FNR protein. Thus FNR can function as an anaerobic repressor as well as an anaerobic transcriptional activator. The results are consistent with the FNR-binding function attributed to the proposed consensus sequence. Using frdA- and ndh-lacZ fusions exhibiting positive and negative regulation by FNR, it was further shown that the depletion of metal ions in growth media with chelating agents mimics oxygen with respect to the activity of FNR. Possible roles for metal ions in the oxygen-sensing pathway associated with FNR function are discussed.
authors.affiliation: Department of Molecular Biology and Biotechnology, University of Sheffield, UK.
authors.forename: S
authors.initials: S
authors.lastname: Spiro
authors.forename: R E
authors.initials: RE
authors.lastname: Roberts
authors.forename: J R
authors.initials: JR
authors.lastname: Guest
mesh_terms: D000595:Amino Acid Sequence; D000693:Anaerobiosis; D001426:Bacterial Proteins / Q000502:physiology*; D001483:Base Sequence; D002614:Chelating Agents / Q000494:pharmacology; D003001:Cloning, Molecular; D003579:Cytochrome Reductases / Q000235:genetics*; D004492:Edetic Acid / Q000494:pharmacology; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins; D005786:Gene Expression Regulation; D005798:Genes, Bacterial; D007506:Iron-Sulfur Proteins; D008670:Metals / Q000502:physiology*; D008956:Models, Chemical; D008969:Molecular Sequence Data; D009243:NAD; D009245:NADH Dehydrogenase / Q000235:genetics*; D010618:Phenanthrolines / Q000494:pharmacology; D010957:Plasmids; D013385:Succinate Dehydrogenase / Q000235:genetics; D014157:Transcription Factors / Q000502:physiology*; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D002614:Chelating Agents; D029968:Escherichia coli Proteins; C060704:FNR protein, E coli; D007506:Iron-Sulfur Proteins; D008670:Metals; D010618:Phenanthrolines; D014157:Transcription Factors; D009243:NAD; D004492:Edetic Acid; D013385:Succinate Dehydrogenase; D003579:Cytochrome Reductases; D009245:NADH Dehydrogenase; D001616:beta-Galactosidase; C025205:1,10-phenanthroline