Hamel P, Sakamoto W, Wintz H, Dujardin G
Centre de Génétique Moléculaire, Gif sur Yvette, France.
Plant J. 1997 Dec;12(6):1319-27. doi: 10.1046/j.1365-313x.1997.12061319.x.
The nuclear gene OXA1 is essential for respiratory growth in yeast. It codes for a chaperon-like protein, and has pleiotropic effects on the assembly of cytochrome c oxidase and ATP synthase of the mitochondrial respiratory chain. To study respiratory complex formation in plants, we have cloned a homolog of the yeast oxa1- in Arabidopsis thaliana, OXA1At, by functional complementation of a yeast oxa1- mutant. OXA1At is a single copy gene and appears to be constitutively expressed in A. thaliana. Although OXA1At encodes a protein sharing only 30% amino acid identity with the yeast Oxa1 protein, hydrophobic domains likely corresponding to trans-membrane domains are strictly conserved. Cytochrome spectra and measurements of respiratory activities show that replacement of the yeast Oxa1 protein with the A. thaliana homolog leads to correct assembly and activity of cytochrome c oxidase, but to partial restoration of ATPase activity. Our results suggest that the Oxa1At protein is essential for the respiratory complex assembly in A. thaliana, and that genes involved in mitochondrial multiprotein complex formation can be conserved between plants and other organisms.
核基因OXA1对酵母的呼吸生长至关重要。它编码一种类似伴侣蛋白的蛋白质，对线粒体呼吸链中细胞色素c氧化酶和ATP合酶的组装具有多效性影响。为了研究植物中的呼吸复合体形成，我们通过对酵母oxa1-突变体进行功能互补，在拟南芥中克隆了酵母oxa1的同源物OXA1At。OXA1At是一个单拷贝基因，在拟南芥中似乎组成性表达。尽管OXA1At编码的蛋白质与酵母Oxa1蛋白的氨基酸同一性仅为30%，但可能对应于跨膜结构域的疏水结构域严格保守。细胞色素光谱和呼吸活性测量表明，用拟南芥同源物替代酵母Oxa1蛋白可导致细胞色素c氧化酶的正确组装和活性，但ATP酶活性只能部分恢复。我们的结果表明，Oxa1At蛋白对拟南芥中的呼吸复合体组装至关重要，并且参与线粒体多蛋白复合体形成的基因在植物和其他生物体之间可以保守。
