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The maize mitochondrial MnSODS encoded by multiple genes are localized in the mitochondrial matrix of transformed

D Zhu1, J G Scandalios

  • 1Department of Genetics, North Carolina State University, Raliegh 27695, USA.

Free Radical Biology & Medicine
|February 1, 1995
PubMed

Insights

All maize mitochondrial manganese superoxide dismutases (MnSODs) are targeted to the mitochondrial matrix. These MnSODs functionally complement manganese superoxide dismutase deficiency and protect yeast cells from oxidative stress.

Area of Science:

  • Plant molecular biology
  • Mitochondrial biochemistry
  • Enzymology

Background:

  • Maize mitochondrial manganese superoxide dismutases (MnSODs) are encoded by a multigene family.
  • Previous studies indicated MnSODs possess mitochondrial transit peptides, suggesting mitochondrial localization.

Purpose of the Study:

  • To determine the precise submitochondrial localization and functional roles of individual maize MnSODs.
  • To investigate the targeting and complementation capabilities of maize MnSODs in a heterologous system.

Main Methods:

  • Molecular cloning and characterization of maize MnSod cDNAs.
  • Functional expression of maize MnSod cDNAs in MnSOD-deficient yeast cells.
  • Biochemical analysis of MnSOD activity and submitochondrial localization.

Main Results:

  • All cloned maize MnSod cDNAs encode precursor proteins with conserved mitochondrial matrix-targeting signals.
  • Transformed yeast cells expressing individual maize MnSODs were rescued from paraquat-induced oxidative stress.
  • Biochemical assays confirmed the expression and mitochondrial matrix targeting of all tested maize MnSODs in yeast.

Conclusions:

  • All maize mitochondrial MnSODs are functional and targeted to the mitochondrial matrix.
  • The conserved matrix-targeting signal ensures the proper localization and function of maize MnSODs within mitochondria.

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