title: A dissimilatory sirohaem-sulfite-reductase-type protein from the hyperthermophilic archaeon Pyrobaculum islandicum.
abstract: A sulfite-reductase-type protein was purified from the hyperthermophilic crenarchaeote Pyrobaculum islandicum grown chemoorganoheterotrophically with thiosulfate as terminal electron acceptor. In common with dissimilatory sulfite reductases the protein has an alpha 2 beta 2 structure and contains high-spin sirohaem, non-haem iron and acid-labile sulfide. The oxidized protein exhibits absorption maxima at 280, 392, 578 and 710 nm with shoulders at 430 and 610 nm. The isoelectric point of pH 8.4 sets the protein apart from all dissimilatory sulfite reductases characterized thus far. The genes for the alpha- and beta-subunits (dsrA and dsrB) are contiguous in the order dsrAdsrB and most probably comprise an operon with the directly following dsrG and dsrC genes. dsrG and dsrC encode products which are homologous to eukaryotic glutathione S-transferases and the proposed gamma-subunit of Desulfovibrio vulgaris sulfite reductase, respectively. dsrA and dsrB encode 44.2 kDa and 41.2 kDa peptides which show significant similarity to the two homologous subunits DsrA and DsrB of dissimilatory sulfite reductases. Phylogenetic analyses indicate a common protogenotic origin of the P. islandicum protein and the dissimilatory sulfite reductases from sulfate-reducing and sulfide-oxidizing prokaryotes. However, the protein from P. islandicum and the sulfite reductases from sulfate-reducers and from sulfur-oxidizers most probably evolved into three independent lineages prior to divergence of archaea and bacteria.
authors.affiliation: Institut für Mikrobiologie & Biotechnologie, Rheinische Friedrich-Wilhelms-Universität Bonn, 53115 Bonn, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Molitor
authors.affiliation: Institut für Mikrobiologie & Biotechnologie, Rheinische Friedrich-Wilhelms-Universität Bonn, 53115 Bonn, Germany.
authors.forename: Christiane
authors.initials: C
authors.lastname: Dahl
authors.affiliation: Institut für Mikrobiologie & Biotechnologie, Rheinische Friedrich-Wilhelms-Universität Bonn, 53115 Bonn, Germany.
authors.forename: Ilka
authors.initials: I
authors.lastname: Molitor
authors.affiliation: Institut für Mikrobiologie & Biotechnologie, Rheinische Friedrich-Wilhelms-Universität Bonn, 53115 Bonn, Germany.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Schäfer
authors.affiliation: Institut für Mikrobiologie & Biotechnologie, Rheinische Friedrich-Wilhelms-Universität Bonn, 53115 Bonn, Germany.
authors.forename: Norbert
authors.initials: N
authors.lastname: Speich
authors.affiliation: Lehrstuhl für Mikrobiologie Universitätsstr. 31, 93053 Regensburg and Institut für Biochemie.
authors.forename: Robert
authors.initials: R
authors.lastname: Huber
authors.affiliation: Universitätsstr. 31, 93053 Regensburg, Germany.
authors.forename: Rainer
authors.initials: R
authors.lastname: Deutzmann
authors.affiliation: Institut für Mikrobiologie & Biotechnologie, Rheinische Friedrich-Wilhelms-Universität Bonn, 53115 Bonn, Germany.
authors.forename: Hans G
authors.initials: HG
authors.lastname: Trüper
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000032:analysis / Q000235:genetics; D016969:Desulfovibrio vulgaris / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D005798:Genes, Bacterial; D005982:Glutathione Transferase / Q000235:genetics / Q000378:metabolism; D006418:Heme / Q000031:analogs & derivatives* / Q000378:metabolism; D007526:Isoelectric Point; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D009876:Operon; D010084:Oxidation-Reduction; D050862:Oxidoreductases Acting on Sulfur Group Donors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D010802:Phylogeny; D010957:Plasmids; D011487:Protein Conformation; D011995:Recombination, Genetic; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D019624:Thermoproteaceae / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism; D013885:Thiosulfates / Q000378:metabolism
chemical_list: D004269:DNA, Bacterial; D013885:Thiosulfates; D006418:Heme; C009272:siroheme; D050862:Oxidoreductases Acting on Sulfur Group Donors; D005982:Glutathione Transferase