CLONING AND EXPRESSION OF SUPEROXIDE-DISMUTASE FROM AQUIFEX PYROPHILUS, A HYPERTHERMOPHILIC BACTERIUM

A superoxide dismutase (SOD) gene of Aquifex pyrophilus, a marine hype rthermophilic bacterium, was cloned, sequenced, expressed in Escherich ia coli, and its gene product characterized. This is the first SOD fro m a hyperthermophilic bacterium that has been cloned. It is an iron-co ntaining homooligomeric protein with a monomeric molecular mass of 24. 2 kDa. The DNA-derived amino acid sequence is more similar to those of known Mn- and Fe-SODs from thermophilic archaea than of Cu, Zn-SODs. The metal binding residues found in all SOD sequences from different s pecies are also conserved in A. pyrophilus SOD. The protein is biochem ically active only as an oligomer and is resistant to thermal denatura tion. (C) 1997 Federation of European Biochemical Societies.