Characterization of the manganese-containing superoxide dismutase and its gene regulation in stress response of Schizosaccharomyces pombe

Fission yeast Schizosaccharomyces pombe contains two superoxide dismutases (SODs), one in the cytosol and the other in mitochondria. The sod2(+) gene encoding putative mitochondrial superoxide dismutase containing manganese ( MnSOD) has been isolated. Purification and analysis of the sod2(+) gene pro duct revealed that it contained only manganese as a cofactor, thus verified to be a genuine MnSOD. It was localized in mitochondria as expected. Its N -terminal amino acid sequence indicated that the mitochondrial targeting se quence of 21 amino acids was removed. The native form consisted of two iden tical subunits. The sod2(+) expression was induced by external stresses, su ch as treatments with superoxide generators, high osmolarity, and heat. The induction by these stress treatments depended on Wis1-Spc1 MAPK signal tra nsduction pathway being independent of transcription factors Atf1 or Pap1. The sod2 disruption rendered cells sensitive to various superoxide-generato rs, heat, and high osmolarity, suggesting that the mitochondrial MnSOD acts as a general defense agent against multiple stresses. (C) 2001 Academic Pr ess.