title: Aeropyrum pernix K1, a strictly aerobic and hyperthermophilic archaeon, has two terminal oxidases, cytochrome ba3 and cytochrome aa3.
abstract: Aeropyrum pernix K1 is a strictly aerobic and hyperthermophilic archaeon that thrives even at 100 degrees C. The archaeon is quite interesting with respect to the evolution of aerobic electron transport systems and the thermal stability of the respiratory components. An isolated membrane fraction was found to oxidize bovine cytochrome c. The activity was solubilized in the presence of detergents and separated into two fractions by successive chromatography. Two cytochrome oxidases, designated as CO-1 and CO-2, were further purified. CO-1 was a ba(3)-type cytochrome containing at least two subunits. Chemically digested fragments of CO-1 revealed a peptide with a sequence identical to a part of a putative cytochrome oxidase subunit I encoded by the gene ape1623. CO-2, an aa(3)-type cytochrome, was present in lower amounts than CO-1 and was immunologically identified as a product of aoxABC gene (DDBJ accession no. AB020482). Both cytochromes reacted with carbon monoxide. The apparent K(m) values of CO-1 and CO-2 for oxygen were 5.5 and 32 micro M, respectively, at 25 degrees C. The terminal oxidases CO-1 and CO-2 phylogenetically correspond to the SoxB and SoxM branches, respectively, of the heme-copper oxidase tree.
authors.affiliation: Department of Biotechnology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Ryuhei
authors.initials: R
authors.lastname: Ishikawa
authors.forename: Yoko
authors.initials: Y
authors.lastname: Ishido
authors.forename: Atsuo
authors.initials: A
authors.lastname: Tachikawa
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kawasaki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Matsuzawa
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Wakagi
mesh_terms: D000332:Aerobiosis; D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D003573:Cytochrome b Group / Q000235:genetics* / Q000302:isolation & purification / Q000502:physiology*; D019641:DNA, Archaeal / Q000032:analysis; D019620:Desulfurococcaceae / Q000201:enzymology*; D003576:Electron Transport Complex IV / Q000235:genetics* / Q000302:isolation & purification / Q000502:physiology*; D004591:Electrophoresis, Polyacrylamide Gel; D006358:Hot Temperature; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010802:Phylogeny; D012492:Salts / Q000378:metabolism; D016415:Sequence Alignment; D013772:Tetramethylphenylenediamine / Q000378:metabolism
chemical_list: D003573:Cytochrome b Group; D019641:DNA, Archaeal; D012492:Salts; C058557:cytochrome ba3; D003576:Electron Transport Complex IV; D013772:Tetramethylphenylenediamine