Eubel Holger, Heinemeyer Jesco, Braun Hans-Peter
Institut für Angewandte Genetik, Universität Hannover, D-30419 Hannover, Germany.
Plant Physiol. 2004 Apr;134(4):1450-9. doi: 10.1104/pp.103.038018. Epub 2004 Apr 2.
Plant mitochondria were previously shown to comprise respiratory supercomplexes containing cytochrome c reductase (complex III) and NADH dehydrogenase (complex I) of I(1)III(2) and I(2)III(4) composition. Here we report the discovery of additional supercomplexes in potato (Solanum tuberosum) mitochondria, which are of lower abundance and include cytochrome c oxidase (complex IV). Highly active mitochondria were isolated from potato tubers and stems, solubilized by digitonin, and subsequently analyzed by Blue-native (BN) polyacrylamide gel electrophoresis (PAGE). Visualization of supercomplexes by in-gel activity stains for complex IV revealed five novel supercomplexes of 850, 1,200, 1,850, 2,200, and 3,000 kD in potato tuber mitochondria. These supercomplexes have III(2)IV(1), III(2)IV(2), I(1)III(2)IV(1), I(1)III(2)IV(2), and I(1)III(2)IV(4) compositions as shown by two-dimensional BN/sodium dodecyl sulfate (SDS)-PAGE and BN/BN-PAGE in combination with activity stains for cytochrome c oxidase. Potato stem mitochondria include similar supercomplexes, but complex IV is partially present in a smaller version that lacks the Cox6b protein and possibly other subunits. However, in mitochondria from potato tubers and stems, about 90% of complex IV was present in monomeric form. It was suggested that the I(1)III(2)IV(4) supercomplex represents a basic unit for respiration in mammalian mitochondria termed respirasome. Respirasomes also occur in potato mitochondria but were of low concentrations under all conditions applied. We speculate that respirasomes are more abundant under in vivo conditions.
先前的研究表明，植物线粒体包含呼吸超级复合体，其由细胞色素c还原酶（复合体III）和NADH脱氢酶（复合体I）组成，分别为I(1)III(2)和I(2)III(4)结构。在此，我们报告在马铃薯（Solanum tuberosum）线粒体中发现了其他超级复合体，其丰度较低，且包含细胞色素c氧化酶（复合体IV）。从马铃薯块茎和茎中分离出高活性线粒体，用洋地黄皂苷使其增溶，随后通过蓝色非变性（BN）聚丙烯酰胺凝胶电泳（PAGE）进行分析。通过对复合体IV进行凝胶内活性染色来可视化超级复合体，结果显示在马铃薯块茎线粒体中存在5种新的超级复合体，分子量分别为850、1200、1850、2200和3000 kD。二维BN/十二烷基硫酸钠（SDS）-PAGE以及BN/BN-PAGE结合细胞色素c氧化酶活性染色结果表明，这些超级复合体的结构分别为III(2)IV(1)、III(2)IV(2)、I(1)III(2)IV(1)、I(1)III(2)IV(2)和I(1)III(2)IV(4)。马铃薯茎线粒体包含类似的超级复合体，但复合体IV部分以较小的形式存在，该形式缺少Cox6b蛋白以及可能的其他亚基。然而，在马铃薯块茎和茎的线粒体中，约90%的复合体IV以单体形式存在。有人提出，I(1)III(2)IV(4)超级复合体代表了哺乳动物线粒体呼吸的基本单元，称为呼吸体。呼吸体也存在于马铃薯线粒体中，但在所应用的所有条件下浓度都很低。我们推测，在体内条件下呼吸体更为丰富。
