Aempyrum pernix K1, a strictly aerobic and hyperthermophilic archaeon, has two terminal oxidases, cytochromeBa3 and cytochromeaa3

• Published in: Archives of microbiology Vol. 179; no. 1; pp. 42 - 49
• Main Authors: Ishikawa, Ryuhei, Ishido, Yoko, Tachikawa, Atsuo, Kawasaki, Hiroshi, Matsuzawa, Hiroshi, Wakagi, Takayoshi
• Format: Journal Article
• Language: English
• Published: Berlin Springer Nature B.V 01.01.2002
• Subjects: Carbon monoxide; Cytochrome; Cytochromes; Detergents; Electron transport; Heme; Oxidase; Phylogeny; Thermal stability; Transportation systems
• ISSN: 0302-8933; 1432-072X
• DOI: 10.1007/s00203-002-0496-1

Aeropyrum pernix K1 is a strictly aerobic and hyperthermophiiic archaeon that thrives even at 100 °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 cytochromec. 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 aba3-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 geneape 1623. CO-2, anaa3-type cytochrome, was present in lower amounts than CO-1 and was immunologically identified as a product ofaoxABC gene (DDBJ accession no. AB020482). Both cytochromes reacted with carbon monoxide. The apparentKm values of CO-1 and CO-2 for oxygen were 5.5 and 32 µM, respectively, at 25 °C. The terminal oxidases CO-1 and CO-2 phylogenetically correspond to the SoxB and SoxM branches, respectively, of the heme-copper oxidase tree.