Characterization of a superoxide dismutase gene from the archaebacterium Methanobacterium thermoautotrophicum.

A gene encoding superoxide dismutase (SOD) was cloned from the archaebacterium Methanobacterium thermoautotrophicum, the first example from an anaerobic bacterium. The deduced amino acid sequence showed overall similarity to sequences of known Mn- and Fe-SODs from aerobic organisms. Judging from a detailed sequence comparison, the cloned SOD gene is classified as Mn-SOD. By comparison of Mn-SOD sequences among various species it was suggested that archaebacterial superoxide dismutase is a direct descendant of a primordial enzyme. Between a putative promoter and the start codon there is an inverted repeat sequence which is also found in the counterpart of Halobacterium halobium.