The nuclear origin of the non-phosphorylating NADH dehydrogenases of plant mitochondria.
The oxidation of matrix and cytosolic NADH by isolated beetroot and wheat leaf mitochondria was investigated to determine whether the rotenone-insensitive NADH dehydrogenases of plant mitochondria were the products of nuclear or mitochondrial genes. After aging beetroot tissue (slicing and incubating in a CaSO4 solution), the induction of the level of matrix NADH oxidation in the presence of rotenone was greatly reduced in mitochondria isolated from tissue treated with cycloheximide, a nuclear protein synthesis inhibitor. This was also true for the oxidation of cytosolic NADH. Mitochondria isolated from chloramphenicol-treated tissue exhibited greatly increased levels of both matrix and external rotenone-insensitive NADH oxidation when compared to the increase due to the aging process alone. This increase was not accompanied by an increase in matrix NAD-linked substrate dehydrogenases such as malic enzyme nor intra-mitochondrial NAD levels. Possible explanations for this increase in rotenone-insensitive NADH oxidation are discussed. Based on these results we have concluded that the matrix facing rotenone-insensitive NADH dehydrogenase of plant mitochondria is encoded by a nuclear gene and synthesis of the protein occurs in the cytosol.
School of Biological Sciences, The Flinders University of South Australia, Melbourne, Australia. rebecca.cook-johnson@flinders.edu.au
R J
RJ
Cook-Johnson
Q
Q
Zhang
J T
JT
Wiskich
K L
KL
Soole
D002467:Cell Nucleus / Q000235:genetics*; D019663:Chenopodiaceae / Q000235:genetics; D002701:Chloramphenicol / Q000494:pharmacology; D003513:Cycloheximide / Q000494:pharmacology; D004272:DNA, Mitochondrial; D017343:Genes, Plant; D006863:Hydrogen-Ion Concentration; D008293:Malates / Q000494:pharmacology; D009245:NADH Dehydrogenase / Q000235:genetics* / Q000502:physiology*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D013997:Time Factors
D004272:DNA, Mitochondrial; D008293:Malates; D011500:Protein Synthesis Inhibitors; D002701:Chloramphenicol; C030298:malic acid; D003513:Cycloheximide; D009245:NADH Dehydrogenase