The nuclear origin of the non‐phosphorylating NADH dehydrogenases of plant mitochondria

Abstract

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 CaSO 4 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.z 1999 Federation of European Biochemical Societies.

PLANT MITOCHONDRIA AND OXIDATIVE STRESS: Electron Transport, NADPH Turnover, and Metabolism of Reactive Oxygen Species

“…Since the concentration of NAD + in the mitochondria was unchanged, an increased NDin(NADH) activity was probably responsible. No induction was seen when cycloheximide was present in the aging solution, indicating that NDin(NADH) is encoded by a nuclear gene (18). This is consistent with the absence of NDA homologues in the mitochondrial genome in Arabidopsis (116,137).…”

“…However, both NDex(NADH) activity and AOX capacity appeared to be several-fold higher in mitochondria from chloramphenicol-treated wheat leaves than in mitochondria from control leaves (153). Chloramphenicol treatment of red beetroot slices during washing gave an increased rate of rotenone-insensitive malate oxidation, indicating that NDin(NADH) [or possibly NDin(NADPH)] was induced (18).…”

Rotenone-insensitive NAD(P)H dehydrogenases in plants: Immunodetection and distribution of native proteins in mitochondria

“…In order to analyse the presence of immunorecognised proteins in correlation to NAD(P)H dehydrogenase activities we investigated red beetroot induction (figure 8). Beetroots are known to induce external NADH oxidation, to a smaller extent the rotenone-insensitive internal NADH oxidation, but not external NADPH oxidation, during washing of tissue slices [1,3,37]. A similar induction, specific for external NADH oxidation and not involving the external NADPH dehydrogenase is seen upon long-term storage of intact beets at 10 °C [9].…”

“…Red beetroots constitute the only known plant tissue where mitochondrial rotenone-insensitive NADH dehydrogenases can be induced [3,26,37]. On washing sliced beetroots, the external NADH dehydrogenase in isolated mitochondria increased 3.5-fold whereas the internal rotenone-insensitive NADH dehydrogenase increased only 1.8-fold (figure 8).…”