THE MAIZE MITOCHONDRIAL MNSODS ENCODED BY MULTIPLE GENES ARE LOCALIZED IN THE MITOCHONDRIAL MATRIX OF TRANSFORMED YEAST-CELLS

We recently demonstrated that maize mitochondrial MnSODs are encoded b y a differentially expressed multigene family. Molecular characterizat ion of the cloned maize MnSod cDNAs shows that all the maize MnSODs en coded by the cloned MnSod have mitochondrial transit peptides and that the matrix-targeting signal was conserved in all the MnSOD precursor proteins, suggesting that all the maize MnSODs are associated with mit ochondria in vivo. In an attempt to clarify the submitochondrial local ization of each individual maize MnSOD, each of the maize MnSod cDNAs was introduced into the MnSOD-deficient yeast cells. The functional ro le and submitochondrial location of each individual MnSOD were examine d in the transformed yeast cells. Herein, we demonstrate that all the maize MnSODs can functionally complement the MnSOD deficiency and resc ue the transformed yeast cells from oxidative stress induced by paraqu at. Biochemical analyses indicate that all of the maize MnSODs are exp ressed and targeted into the mitochondrial matrix of transformed yeast cells.