title: Identification and expression of the Escherichia coli fdhD and fdhE genes, which are involved in the formation of respiratory formate dehydrogenase.
abstract: The two closely linked fdhD and fdhE genes of Escherichia coli are required for the formation of active membrane-bound phenazine methosulfate-linked formate dehydrogenase (FDH-PMS). Both genes were isolated from a cosmid library. Restriction endonuclease analysis associated with Mu dII1734 insertion mutagenesis indicated that the two genes were separated by at least 4 kilobases and transcribed in opposite orientations. Initial experiments indicate that the region between the two genes seems not to be essential to FDH-PMS activity. fdhD and fdhE were expressed either in maxicells or from the T7 promoter-polymerase system. They were shown to encode proteins with approximate Mr 30,500 and 32,000, respectively. Both proteins appeared in the soluble fraction and were not recognized by an FDH-PMS-specific antiserum. Therefore, neither fdhD nor fdhE plays a structural role in the formation of FDH-PMS. Expression of a phi(fdhD-lacZ) operon fusion was decreased about threefold by aerobiosis but was indifferent to other effectors tested. It was unaffected by pfl, chlA, selA, and fnr mutations. Expression of a phi(fdhE-lacZ) operon fusion was slightly induced by nitrate. This induction, requiring the presence of functional chl and fnr alleles, was mediated via nitrate metabolism. Transcription of phi(fdhE-lacZ) fusion was fully dependent on wild-type sel alleles. This might suggest the participation of fdhE in the synthesis of the selenopolypeptide of FDH-PMS.
authors.affiliation: Unité Mixte 24 du Centre National de la Recherche Scientifique, Institut National des Sciences Appliquées de Lyon, France.
authors.forename: C
authors.initials: C
authors.lastname: Schlindwein
authors.forename: G
authors.initials: G
authors.lastname: Giordano
authors.forename: C L
authors.initials: CL
authors.lastname: Santini
authors.forename: M A
authors.initials: MA
authors.lastname: Mandrand
mesh_terms: D003001:Cloning, Molecular / Q000379:methods; D004251:DNA Transposable Elements; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D005560:Formate Dehydrogenases / Q000235:genetics*; D015870:Gene Expression; D005798:Genes, Bacterial; D005838:Genotype; D009154:Mutation; D010101:Oxygen Consumption; D010957:Plasmids; D011401:Promoter Regions, Genetic; D015183:Restriction Mapping; D013604:T-Phages / Q000235:genetics
chemical_list: D004251:DNA Transposable Elements; D005560:Formate Dehydrogenases; D012321:DNA-Directed RNA Polymerases