Golik P, Szczepanek T, Bartnik E, Stepien P P, Lazowska J
Centre de Génétique Moléculaire du CNRS, Yvette, France.
Curr Genet. 1995 Aug;28(3):217-24. doi: 10.1007/BF00309780.
The product of the nuclear gene SUV3 is implicated in a variety of post-transcriptional processes in yeast mitochondria. We have analysed the effect of SUV3 gene-disruption on the expression of intron-containing alleles of the mitochondrial cytb and cox1 genes. We have constructed several strains with mitochondrial genomes containing different combinations of cytb and cox1 introns, and associated these genomes with the disruption of SUV3. The resulting strains were tested for their respiratory competence and spectral cytochrome content. All the strains containing only two or three introns showed normal expression of cytb and cox1, whereas the strains containing more introns were unable to express the appropriate gene. The analysis of mitochondrial RNAs by Northern hybridisation showed that the loss of respiratory competence in the strains containing more introns is due to the decrease of mRNA level with no over-accumulation of high-molecular-weight precursors. However, the transcription of the genes was not affected. These results led us to the notion that SUV3 is required for the stability of intron-containing cytb and cox1 transcripts in a cumulative way, not dependent on any particular intron.
核基因SUV3的产物与酵母线粒体中的多种转录后过程有关。我们分析了SUV3基因破坏对线粒体细胞色素b（cytb）和细胞色素c氧化酶亚基1（cox1）基因含内含子等位基因表达的影响。我们构建了几种线粒体基因组含有不同cytb和cox1内含子组合的菌株，并将这些基因组与SUV3的破坏相关联。对所得菌株的呼吸能力和光谱细胞色素含量进行了测试。所有仅含有两个或三个内含子的菌株cytb和cox1表达正常，而含有更多内含子的菌株无法表达相应基因。通过Northern杂交分析线粒体RNA表明，含有更多内含子的菌株呼吸能力丧失是由于mRNA水平降低，且高分子量前体没有过度积累。然而，基因的转录不受影响。这些结果使我们认为，SUV3以累积方式是含内含子的cytb和cox1转录本稳定性所必需的，不依赖于任何特定内含子。
