title: Purification and properties of an extremely thermostable membrane-bound sulfur-reducing complex from the hyperthermophilic Pyrodictium abyssi.
abstract: The chemolithoautotrophic archaeon Pyrodictium abyssi isolate TAG 11 gains energy by reducing sulfur with H2 to H2S. From this hyperthermophile, a sulfur-reducing complex catalyzing this reaction was purified 13.5-fold. The native complex exhibited a brownish-yellow colour and showed an apparent molecular mass of 520 kDa. SDS/PAGE revealed the presence of nine different major polypeptides with apparent molecular masses of 82, 72, 65, 50, 47, 42, 40, 30 and 24 kDa. The native complex contained 50-55 mol acid-labile sulfur, 50-55 mol iron, 1.6 mol nickel, 1.2 mol copper, 2.8 mol cytochrome b and 0.3 mol cytochrome c (all per mol native complex). The temperature optimum of the H2:sulfur oxidoreductase complex was 100 degrees C, which is consistent with the physiological growth optimum of the native organism. The complex is extremely heat stable. During 5 h incubation at 100 degrees C, no decrease in H2S-forming activity could be observed.
authors.affiliation: Lehrstuhl für Mikrobiologie, Regensburg, Germany. reinhard.dirmeier@biologie.uni-regensburg.de
authors.forename: R
authors.initials: R
authors.lastname: Dirmeier
authors.forename: M
authors.initials: M
authors.lastname: Keller
authors.forename: G
authors.initials: G
authors.lastname: Frey
authors.forename: H
authors.initials: H
authors.lastname: Huber
authors.forename: K O
authors.initials: KO
authors.lastname: Stetter
mesh_terms: D000595:Amino Acid Sequence; D001105:Archaea / Q000201:enzymology; D001419:Bacteria / Q000201:enzymology; D002462:Cell Membrane / Q000201:enzymology; D002850:Chromatography, Gel; D003573:Cytochrome b Group / Q000378:metabolism; D003574:Cytochrome c Group / Q000378:metabolism; D019620:Desulfurococcaceae / Q000201:enzymology* / Q000254:growth & development; D006358:Hot Temperature; D007700:Kinetics; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009097:Multienzyme Complexes / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013455:Sulfur / Q000378:metabolism*
chemical_list: D003573:Cytochrome b Group; D003574:Cytochrome c Group; D046911:Macromolecular Substances; D009097:Multienzyme Complexes; D013455:Sulfur; D010088:Oxidoreductases