Key Laboratory of Molecular Biophysics of Chinese Ministry of Education, Center for Human Genome Research, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China.
Int J Mol Sci. 2022 Feb 19;23(4):2327. doi: 10.3390/ijms23042327.
Nuclear-encoded Atp23 was previously shown to have dual functions, including processing the yeast Atp6 precursor and assisting the assembly of yeast mitochondrial ATP synthase. However, it remains unknown whether there are genes functionally complementary to to rescue null mutant. In the present paper, we screen and characterize three revertants of null mutant and reveal a T1121G point mutation in the mitochondrial gene coding sequence, which leads to Val374Gly mutation in Cox1, the suppressor in the revertants. This was verified further by the partial restoration of mitochondrial ATP synthase assembly in null mutant transformed with exogenous hybrid mutant plasmid. The predicted tertiary structure of the Cox1 p.Val374Gly mutation showed no obvious difference from wild-type Cox1. By further chase labeling with isotope [S]-methionine, we found that the stability of Atp6 of ATP synthase increased in the revertants compared with the null mutant. Taking all the data together, we revealed that the T1121G point mutation of mitochondrial gene could partially restore the unassembly of mitochondrial ATP synthase in null mutant by increasing the stability of Atp6. Therefore, this study uncovers a gene that is partially functionally complementary to to rescue deficiency, broadening our understanding of the relationship between yeast the cytochrome c oxidase complex and mitochondrial ATP synthase complex.
先前的研究表明，核编码的 Atp23 具有双重功能，包括加工酵母 Atp6 前体和协助酵母线粒体 ATP 合酶的组装。然而，目前尚不清楚是否存在与 Atp23 基因在功能上互补的基因，以挽救 atp23 缺失突变体。在本研究中，我们筛选并鉴定了 atp23 缺失突变体的三个回复突变体，并揭示了线粒体基因 编码序列中的 T1121G 点突变，导致 Cox1 中的 Val374Gly 突变，Cox1 是回复突变体中的抑制因子。这进一步通过将外源性杂交 突变质粒转化为 atp23 缺失突变体，部分恢复线粒体 ATP 合酶组装得到验证。预测的 Cox1 p.Val374Gly 突变的三级结构与野生型 Cox1 没有明显差异。通过进一步用同位素 [S]-甲硫氨酸进行追踪标记，我们发现与 atp23 缺失突变体相比，ATP 合酶中 Atp6 的稳定性在回复突变体中增加。综合所有数据，我们揭示了线粒体基因 的 T1121G 点突变可以通过增加 Atp6 的稳定性，部分恢复 atp23 缺失突变体中线粒体 ATP 合酶的未组装。因此，本研究揭示了一个与 Atp23 基因在功能上部分互补的基因，以挽救 atp23 缺陷，拓宽了我们对酵母细胞色素 c 氧化酶复合物和线粒体 ATP 合酶复合物之间关系的理解。
