Rj. Cook-johnson et al., The nuclear origin of the non-phosphorylating NADH dehydrogenases of plantmitochondria, FEBS LETTER, 454(1-2), 1999, pp. 37-41
The oxidation of matrix and cytosolic NADH by isolated beetroot and wheat l
eaf mitochondria was investigated tb determine whether the rotenone-insensi
tive NADH dehydrogenases of plant mitochondria were the products of nuclear
or mitochondrial genes. After aging beetroot tissue (slicing and incubatin
g in a CaSO4 solution), the induction of the level of matrix NADH oxidation
in the presence of rotenone was greatly reduced in mitochondria isolated f
rom tissue treated with cycloheximide, a nuclear protein synthesis inhibito
r. This was also true for the oxidation of cytosolic NADH, Mitochondria iso
lated from chloramphenicol-treated tissue exhibited greatly increased level
s of both matrix and external rotenone-insensitive NADH oxidation when comp
ared to the increase due to the aging process alone. This increase was not
accompanied by an increase in matrix NAD-linked substrate dehydrogenases su
ch as malic enzyme nor intra-mitochondrial NAD levels. Possible explanation
s for this increase in rotenone-insensitive NADH oxidation are discussed. B
ased on these results we have concluded that the matrix facing rotenone-ins
ensitive NADH dehydrogenase of plant mitochondria is encoded by a nuclear g
ene and synthesis of the protein occurs in the cytosol, (C) 1999 Federation
of European Biochemical Societies.