An azide-insensitive superoxide dismutase from a hyperthermophilic archaeon, Sulfolobus solfataricus.
The superoxide dismutase (SOD) gene of Sulfolobus solfataricus, a hyperthermophilic archaeon, was cloned and expressed in Escherichia coli, and its gene product was characterized. When the protein was expressed in E. coli, it formed a homodimer that contained both Mn and Fe. Metal reconstitution experiments of the SOD with Fe or Mn showed that only the Fe-reconstituted SOD was active. Substitution of Tyr88 to Phe did not affect the metal specificity of the enzyme. The Fe-reconstituted SOD was extremely resistant to thermal denaturation; e.g. 96% of the initial activity was retained after heating at 95 degreesC for 2 h. Fe-reconstituted SOD was not inhibited by azide, but fluoride inhibition was observed. This suggests that some steric hindrance in the substrate funnel of the enzyme prevents the access of N3- but allows O2- and F- access to the active site.
Yamano
S
S
Marine Biotechnology Institute, Shimizu Laboratories, Shimizu, Shizuoka, 424-0037, Japan. syamano@kirin.co.jp
Maruyama
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T
D000595:Amino Acid Sequence; D001386:Azides / Q000494:pharmacology*; D001483:Base Sequence; D003001:Cloning, Molecular; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019766:Genes, Archaeal; D007501:Iron / Q000378:metabolism; D008345:Manganese / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D017386:Sequence Homology, Amino Acid; D019810:Sodium Azide / Q000494:pharmacology; D016944:Sulfolobus / Q000201:enzymology* / Q000235:genetics; D013482:Superoxide Dismutase / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism*
D001386:Azides; D004791:Enzyme Inhibitors; D008345:Manganese; D019810:Sodium Azide; D007501:Iron; D013482:Superoxide Dismutase