title: Acidianus ambivalens type-II NADH dehydrogenase: genetic characterisation and identification of the flavin moiety as FMN.
abstract: The thermoacidophilic archaeon Acidianus ambivalens contains a monomeric 47 kDa type-II NADH dehydrogenase (NDH), which contains a covalently bound flavin. In this work, by a combination of several methods, namely (31)P-nuclear magnetic resonance and fluorescence spectroscopies, it is proven that this enzyme contains covalent FMN, a novelty among this family of enzymes, which were so far thought to mainly have the flavin dinucleotide form. Discrimination between several possible covalent flavin linkages was achieved by spectral and fluorescence experiments, which identified an 8alpha-N(1)-histidylflavin-type of linkage. Analysis of the gene-deduced amino acid sequence of type-II NDH showed no transmembranar helices and allowed the definition of putative dinucleotide and quinone binding motifs. Further, it is suggested that membrane anchoring can be achieved via amphipatic helices.
authors.affiliation: Instituto de Tecnologia Qui;mica e Biológica, Universidade Nova de Lisboa, Rua da Quinta Grande 6, Oeiras, Portugal.
authors.forename: Tiago M
authors.initials: TM
authors.lastname: Bandeiras
authors.forename: Carlos
authors.initials: C
authors.lastname: Salgueiro
authors.forename: Arnulf
authors.initials: A
authors.lastname: Kletzin
authors.forename: Cláudio M
authors.initials: CM
authors.lastname: Gomes
authors.forename: Miguel
authors.initials: M
authors.lastname: Teixeira
mesh_terms: D000595:Amino Acid Sequence; D005486:Flavin Mononucleotide / Q000032:analysis* / Q000378:metabolism; D006639:Histidine / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics; D008969:Molecular Sequence Data; D009245:NADH Dehydrogenase / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D019906:Nuclear Magnetic Resonance, Biomolecular; D017433:Protein Structure, Secondary; D013050:Spectrometry, Fluorescence; D016943:Sulfolobaceae / Q000201:enzymology*
chemical_list: D008565:Membrane Proteins; D006639:Histidine; D005486:Flavin Mononucleotide; C088908:NADH dehydrogenase II; D009245:NADH Dehydrogenase