Identification of a gene coding for manganese superoxide dismutase from the cellular slime mold Dictyostelium discoideum

Abstract

The soil-dwelling social amoeba Dictyostelium discoideum is known to be unusually resistant to oxidative stress. However, little is known about how D. discoideum cells protect themselves from the stress. We found a gene coding for manganese superoxide dismutase (MnSOD) in the database of D. discoideum. The gene, designated sodE, encodes a polypeptide 37% identical to Escherichia coli MnSOD. A plasmid expressing the truncated form of SodE, pSOD5, was constructed to determine whether SodE suppressed E. coli JI132 (sodA sodB). Experimental results showed that JI132 transformed by pSOD5 was more tolerant of menadione than was JI132 carrying a control vector and that the mutation rate of JI132 carrying pSOD5 was lower than that of JI132 harboring the control vector.