First characterisation of the active oligomer form of sulfur oxygenase reductase from the bacterium Aquifex aeolicus.
Sulfur oxygenase reductase (SOR) enzyme is responsible for the initial oxidation step of elemental sulfur in archaea. Curiously, Aquifex aeolicus, a hyperthermophilic, chemolithoautotrophic and microaerophilic bacterium, has the SOR-encoding gene in its genome. We showed, for the first time the presence of the SOR enzyme in A. aeolicus, its gene was cloned and recombinantly expressed in Escherichia coli and the protein was purified and characterised. It is a 16 homo-oligomer of approximately 600 kDa that contains iron atoms indispensable for the enzyme activity. The optimal temperature of SOR activity is 80 degrees C and it is inactive at 20 degrees C. Studies of the factors involved in getting the fully active molecule at high temperature show clearly that (1) incubation at high temperature induces more homogeneous form of the enzyme, (2) conformational changes observed at high temperature are required to get the fully active molecule and (3) acquisition of an active conformation induced by the temperature seems to be more important than the subunit number. Differences between A. aeolicus SOR and the archaea SORs are described.
Laboratoire de Bioénergétique et Ingénierie des Protéines, IBSM-CNRS, 31 Chemin Joseph Aignier, 13402 Marseille, France.
Nicolas
N
Pelletier
Gisèle
G
Leroy
Marianne
M
Guiral
Marie-Thérèse
MT
Giudici-Orticoni
Corinne
C
Aubert
D001105:Archaea / Q000201:enzymology / Q000235:genetics; D019843:Archaeal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001420:Bacteria, Aerobic / Q000201:enzymology* / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D015870:Gene Expression; D006358:Hot Temperature; D010084:Oxidation-Reduction; D050862:Oxidoreductases Acting on Sulfur Group Donors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D020836:Protein Structure, Quaternary / Q000502:physiology; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013455:Sulfur / Q000378:metabolism
D019843:Archaeal Proteins; D001426:Bacterial Proteins; D011994:Recombinant Proteins; D013455:Sulfur; D050862:Oxidoreductases Acting on Sulfur Group Donors