title: Essential roles for the products of the napABCD genes, but not napFGH, in periplasmic nitrate reduction by Escherichia coli K-12.
abstract: The seven nap genes at minute 47 on the Escherichia coli K-12 chromosome encode a functional nitrate reductase located in the periplasm. The molybdoprotein, NapA, is known to be essential for nitrate reduction. We now demonstrate that the two c-type cytochromes, the periplasmic NapB and the membrane-associated NapC, as well as a fourth polypeptide, NapD, are also essential for nitrate reduction in the periplasm by physiological substrates such as glycerol, formate and glucose. None of the three iron-sulphur proteins, NapF, NapG or NapH, are essential, irrespective of whether the bacteria are grown anaerobically in the presence of nitrate or fumarate as a terminal electron acceptor, or by glucose fermentation. Mutation of napD resulted in the total loss of Methyl Viologen-dependent nitrate reductase activity of the molybdoprotein, NapA, consistent with an earlier suggestion by others that NapD might be required for post-translational modification of NapA.
authors.affiliation: School of Biochemistry, University of Birmingham, Birmingham B15 2TT, U.K.
authors.forename: L C
authors.initials: LC
authors.lastname: Potter
authors.forename: J A
authors.initials: JA
authors.lastname: Cole
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D001483:Base Sequence; D003574:Cytochrome c Group / Q000235:genetics / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D004579:Electron Transport; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D029968:Escherichia coli Proteins; D005285:Fermentation; D005650:Fumarates / Q000378:metabolism; D017353:Gene Deletion; D005798:Genes, Bacterial; D005947:Glucose / Q000378:metabolism; D009154:Mutation; D050901:Nitrate Reductase; D009565:Nitrate Reductases / Q000235:genetics / Q000378:metabolism; D017942:Nitric Acid / Q000378:metabolism*; D010084:Oxidation-Reduction; D019897:Periplasm / Q000378:metabolism; D010957:Plasmids / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D003574:Cytochrome c Group; D017931:DNA Primers; D029968:Escherichia coli Proteins; D005650:Fumarates; D017942:Nitric Acid; C032005:fumaric acid; D009565:Nitrate Reductases; D050901:Nitrate Reductase; C494404:napA protein, E coli; D005947:Glucose