Cloning and expression of superoxide dismutase from Aquifex pyrophilus, a hyperthermophilic bacterium

Abstract

A superoxide dismutase (SOD) gene of Aquifex pyrophilus, a marine hyperthermophilic bacterium, was cloned, sequenced, expressed in Escherichia coli, and its gene product characterized. This is the first SOD from a hyperthermophilic bacterium that has been cloned. It is an iron-containing 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 species are also conserved in A. pyrophilus SOD. The protein is biochemically active only as an oligomer and is resistant to thermal denaturation. (C) 1997 Federation of European Biochemical Societies.