title: Adenylylsulphate reductase from the sulphate-reducing archaeon Archaeoglobus fulgidus: cloning and characterization of the genes and comparison of the enzyme with other iron-sulphur flavoproteins.
abstract: Adenylylsulphate (adenosine-5'-phosphosulphate, APS) reductase from the extremely thermophilic sulphate-reducing archaeon Archaeoglobus fulgidus is an iron-sulphur flavoprotein containing one non-covalently bound flavin group, eight non-haem iron and six labile sulphide atoms per molecule. Reevaluation of the enzyme structure revealed the presence of two different subunits with molecular masses of 80 and 18.5 kDa. The subunits are arranged in an alpha 2 beta subunit structure. We have cloned and sequenced a 2.7 kb segment of DNA containing the genes for the alpha and beta subunits, which we designate aprA and aprB, respectively. The two genes are separated by 17 bp and localized in the order aprBA. While a putative promoter could not be identified in the vicinity of aprBA a probable termination signal was found just downstream of the translation stop codon of aprA. The codon usage for aprBA shows strong preferences for G and C in the third codon position. aprA encodes a 73.3 kDa polypeptide, which shows significant overall similarities with the flavoprotein subunits of the succinate dehydrogenases from Escherichia coli and Bacillus subtilis and the corresponding flavoprotein of E. coli fumarate reductase. Part of the homologous peptide stretches could be assigned to domains that are involved in the binding of the substrate or of the FAD prosthetic group. aprB encodes a 17.1 kDa polypeptide representing an iron-sulphur protein, seven cysteine residues of which are arranged in two clusters typical of ligands of the iron-sulphur centres in ([Fe3S4][Fe4S4]) 7-Fe ferredoxins.
authors.affiliation: Institut für Mikrobiologie & Biotechnologie, Rheinische Friedrich-Wilhelms-Universität Bonn, Germany.
authors.forename: N
authors.initials: N
authors.lastname: Speich
authors.forename: C
authors.initials: C
authors.lastname: Dahl
authors.forename: P
authors.initials: P
authors.lastname: Heisig
authors.forename: A
authors.initials: A
authors.lastname: Klein
authors.forename: F
authors.initials: F
authors.lastname: Lottspeich
authors.forename: K O
authors.initials: KO
authors.lastname: Stetter
authors.forename: H G
authors.initials: HG
authors.lastname: Trüper
mesh_terms: D000595:Amino Acid Sequence; D001105:Archaea / Q000201:enzymology* / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification; D001483:Base Sequence; D003001:Cloning, Molecular; D016384:Consensus Sequence; D004269:DNA, Bacterial / Q000235:genetics; D005420:Flavoproteins / Q000235:genetics*; D005798:Genes, Bacterial; D007506:Iron-Sulfur Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification; D050862:Oxidoreductases Acting on Sulfur Group Donors; D011487:Protein Conformation; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013431:Sulfates / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D005420:Flavoproteins; D007506:Iron-Sulfur Proteins; D013431:Sulfates; D010088:Oxidoreductases; D050862:Oxidoreductases Acting on Sulfur Group Donors; C019618:adenylylsulfate reductase