Cook-Johnson R J, Zhang Q, Wiskich J T, Soole K L
School of Biological Sciences, The Flinders University of South Australia, Melbourne, Australia.
FEBS Lett. 1999 Jul 2;454(1-2):37-41. doi: 10.1016/s0014-5793(99)00753-x.
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.
为了确定植物线粒体中对鱼藤酮不敏感的NADH脱氢酶是核基因还是线粒体基因的产物，对分离出的甜菜根和小麦叶片线粒体中基质和胞质NADH的氧化进行了研究。在甜菜根组织老化（切片并在CaSO4溶液中孵育）后，在用环己酰亚胺（一种核蛋白合成抑制剂）处理的组织中分离出的线粒体中，鱼藤酮存在时基质NADH氧化水平的诱导作用大大降低。胞质NADH的氧化也是如此。与仅因老化过程导致的增加相比，从氯霉素处理的组织中分离出的线粒体中基质和外部对鱼藤酮不敏感的NADH氧化水平均大幅增加。这种增加并未伴随着基质NAD连接的底物脱氢酶（如苹果酸酶）或线粒体内NAD水平的增加。讨论了对鱼藤酮不敏感的NADH氧化增加的可能解释。基于这些结果，我们得出结论，植物线粒体面向基质的对鱼藤酮不敏感的NADH脱氢酶由核基因编码，蛋白质在细胞质中合成。
