Expression and characteristic of the Cu/Zn superoxide dismutase gene from the insect parasitizing fungus Cordyceps militaris.

A Cu/Zn-superoxide dismutase (SOD) gene was characterized from Cordycepes militaris by gene cloning, heterogeneous expression and function analysis. This 154-aa SOD (CmSOD) was deduced from a 465-bp gene cloned, showing 72-95 % sequence identity to Cu/Zn-SODs from other fungi. The deduced amino acid sequence of the cDNA is highly similar to Beauveria bassiana (95 %), Isaria tenuipes (94 %) and Claviceps purpurea (88 %), respectively. The SOD gene of C. militaris spin 589 bp and consisted of two introns and three exons. The CmSOD coding region sequence was inserted into plasmid pQE-30 in order to construct prokaryotic expression vector, then transformed into Escherichia coli M15 cells for expression, and a mass of rCmSOD was obtained by IPTG induction. The enzyme activity of the purified rCmSOD was approximately 714.48 U/mg after the assay. The study provided a way for in-depth research on the expression and regulation of the CmSOD, and the molecular mechanism of anti-oxidative effect in C. militaris.