Mittelmeier T M, Dieckmann C L
Department of Molecular and Cellular Biology, University of Arizona, Tucson 85721.
Curr Genet. 1990 Dec;18(5):421-8. doi: 10.1007/BF00309911.
The nuclear gene product CBP1 stabilizes cytochrome b transcripts in yeast mitochondria. In cbp1 mutant strains, cytochrome b gene (cob) transcripts are not detectable by Northern blot analysis. The results of previous studies led to the hypothesis that CBP1 interacts with the 5'-untranslated sequence of the cob mRNA, or pre-mRNA, to stabilize the message. To determine what portion of the cob leader is sufficient for interaction with CBP1, we have investigated the stability of transcripts from a novel hybrid gene, cob-oli1, in which the 5'-terminal third of the cob leader sequence was fused to the coding sequence of the gene for ATP synthase subunit 9, oli1. The hybrid cob-oli1 transcript was stable in a strain wild-type at the CBP1 locus, but was undetectable in the cbp1 mutant background. That the cob-oli1 transcript was translated to produce ATP synthase subunit 9 in CBP1 strains containing the cob-oli1 gene was verified by 35S-methionine labeling of mitochondrial proteins. We conclude that the 5'-terminal portion of the cob message is sufficient for CBP1 function and discuss the hypothesis that CBP1 interacts directly with this region of the transcript to promote cob mRNA stability.
核基因产物CBP1可稳定酵母线粒体中的细胞色素b转录本。在cbp1突变菌株中，通过Northern印迹分析无法检测到细胞色素b基因（cob）转录本。先前的研究结果提出了一个假说，即CBP1与cob mRNA或前体mRNA的5'非翻译序列相互作用，以稳定该信使。为了确定cob前导序列的哪一部分足以与CBP1相互作用，我们研究了一个新型杂交基因cob-oli1转录本的稳定性，其中cob前导序列的5'末端三分之一与ATP合酶亚基9基因oli1的编码序列融合。杂交的cob-oli1转录本在CBP1基因座野生型菌株中是稳定的，但在cbp1突变背景中无法检测到。通过对线粒体蛋白进行35S-甲硫氨酸标记，证实了在含有cob-oli1基因的CBP1菌株中，cob-oli1转录本可被翻译产生ATP合酶亚基9。我们得出结论，cob信使的5'末端部分足以实现CBP1的功能，并讨论了CBP1直接与转录本的这一区域相互作用以促进cob mRNA稳定性的假说。
