title: Regulation of the thdF gene, which is involved in thiophene oxidation by Escherichia coli K-12.
abstract: The thdF gene of Escherichia coli encodes a 48 kD protein which is involved in the oxidation of derivatives of the sulphur-containing heterocycle thiophene and which appears to be induced during stationary phase. In this work the upstream regulatory region of the thdF gene was isolated by polymerase chain reaction and inserted in front of the lacZ structural gene. Examination of the resulting thdF-lacZ operon fusions showed that expression of the thdF gene increased as E. coli entered the stationary phase. However, the expression of thdF was not dependent on RpoS (KatF), the stationary phase sigma factor. The thdF gene was subject to substantial catabolite repression by glucose and its expression was also greatly decreased in the absence of oxygen. The thdF-lacZ fusions were not significantly affected by elevated temperature or medium of high osmolarity, nor by mutations in thdA, fadR, arcA, arcB, or fnr. Both multicopy, plasmid-borne fusions and single-copy fusions gave similar results in all of the above cases except that the plasmid-borne fusions still showed substantial expression in the absence of oxygen. The heterocyclic compounds thiophene carboxylic acid, furan carboxylic acid and proline increased expression of the thdF gene by 2- to 3-fold, but only during the stationary phase. Tryptophan, indole, and several indole derivatives had no effect.
authors.affiliation: Department of Microbiology, Southern Illinois University, Carbondale, 62901-6508, USA.
authors.forename: M D
authors.initials: MD
authors.lastname: Zabel
authors.forename: P K
authors.initials: PK
authors.lastname: Bunch
authors.forename: D P
authors.initials: DP
authors.lastname: Clark
mesh_terms: D019677:Artificial Gene Fusion; D001426:Bacterial Proteins / Q000494:pharmacology; D001483:Base Sequence; D001673:Biodegradation, Environmental; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D005798:Genes, Bacterial; D005947:Glucose / Q000494:pharmacology; D006571:Heterocyclic Compounds / Q000494:pharmacology; D008969:Molecular Sequence Data; D010100:Oxygen / Q000494:pharmacology; D016133:Polymerase Chain Reaction; D012808:Sigma Factor / Q000494:pharmacology; D013876:Thiophenes / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D006571:Heterocyclic Compounds; D012808:Sigma Factor; D013876:Thiophenes; C069567:sigma factor KatF protein, Bacteria; D005947:Glucose; D010100:Oxygen