Duroc Yann, Gaillard Catherine, Hiard Sophie, Defrance Marie-Christine, Pelletier Georges, Budar Françoise
Station de Génétique et d'Amélioration des Plantes, Institut Jean-Pierre Bourgin, INRA, Route de Saint-Cyr, 78026 Versailles cedex, France.
Biochimie. 2005 Dec;87(12):1089-100. doi: 10.1016/j.biochi.2005.05.009. Epub 2005 Jun 9.
In cytoplasmic male sterility (CMS), original mitochondrial genes contribute to sex determinism by provoking pollen abortion. The function of the encoded proteins remains unclear. We studied the ORF138 protein, responsible for the 'Ogura' CMS, which is both used in hybrid seed production and present in natural populations. We analyzed the biochemical and structural properties of this protein in male-sterile plants and in E. coli. We showed that this protein spontaneously forms dimers in vitro. Truncated variants of the protein, containing either the hydrophobic or the hydrophilic moiety, also spontaneously dimerize. By fractionating mitochondria, we showed that ORF138 was strongly associated with the inner mitochondrial membrane of male-sterile plants. Our results also strongly suggest that ORF138 forms oligomers in male-sterile plant mitochondria. In E. coli, ORF138 was associated with the plasma membrane, as shown by membrane fractionation, and formed oligomers. The production of this protein strongly inhibited bacterial growth, but not by inhibiting respiration. The observed toxic effects required both the hydrophilic and hydrophobic moieties of the protein.
在细胞质雄性不育（CMS）中，原始线粒体基因通过引发花粉败育来决定性别。所编码蛋白质的功能仍不清楚。我们研究了负责“小仓”CMS的ORF138蛋白，该蛋白既用于杂交种子生产，也存在于自然种群中。我们分析了该蛋白在雄性不育植物和大肠杆菌中的生化及结构特性。我们发现该蛋白在体外能自发形成二聚体。该蛋白的截短变体，无论是包含疏水部分还是亲水部分，也能自发二聚化。通过对线粒体进行分级分离，我们发现ORF138与雄性不育植物的线粒体内膜紧密相关。我们的结果还强烈表明，ORF138在雄性不育植物线粒体中形成寡聚体。在大肠杆菌中，如膜分级分离所示，ORF138与质膜相关，并形成寡聚体。该蛋白的产生强烈抑制细菌生长，但不是通过抑制呼吸作用。观察到的毒性作用需要该蛋白的亲水部分和疏水部分共同存在。
