A second terminal oxidase in Sulfolobus acidocaldarius.
We previously found that the soxABCD operon encodes a quinol oxidase complex in Sulfolobus acidocaldarius and this enzyme was purified and characterized. In this study, we have used a cloning procedure based on the conservation of oxidase sequences and the polymerase chain reaction to isolate a new gene (soxM) encoding a subunit of another terminal oxidase. This terminal oxidase is a fusion between two central components of cytochrome oxidases, subunits I and III. soxM forms a transcriptional unit which is expressed under heterotrophic growth conditions. The corresponding protein was detected by direct protein sequencing in a preparation enriched with a cytochrome absorbing light at 562 nm. This preparation contains a terminal oxidase which is able to oxidize the artificial substrate N,N,N',N'-tetramethyl-p-phenylenediamine. This preparation also contains SoxC, a protein homologous to the mitochondrial cytochrome b, and a Rieske iron-sulphur center. We suggest that SoxM is the core component of a second terminal oxidase complex and that this complex may share a subunit (SoxC) with the SoxABCD complex.
Lübben
M
M
European Molecular Biology Laboratory, Heidelberg, Germany.
Arnaud
S
S
Castresana
J
J
Warne
A
A
Albracht
S P
SP
Saraste
M
M
D000595:Amino Acid Sequence; D019843:Archaeal Proteins; D001483:Base Sequence; D003001:Cloning, Molecular; D004578:Electron Spin Resonance Spectroscopy; D003576:Electron Transport Complex IV / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D005798:Genes, Bacterial; D015151:Immunoblotting; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D015183:Restriction Mapping; D016415:Sequence Alignment; D016945:Sulfolobus acidocaldarius / Q000201:enzymology* / Q000235:genetics; D014158:Transcription, Genetic / Q000235:genetics
D019843:Archaeal Proteins; D011993:Recombinant Fusion Proteins; D003576:Electron Transport Complex IV