Stepien P P, Margossian S P, Landsman D, Butow R A
Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas 75235.
Proc Natl Acad Sci U S A. 1992 Aug 1;89(15):6813-7. doi: 10.1073/pnas.89.15.6813.
Mitochondrial gene expression is controlled largely through the action of products of the nuclear genome. The yeast nuclear gene suv3 has been implicated in a variety of mitochondrial posttranscriptional processes and in translation and, thus, represents a key control element in nuclear-mitochondrial interactions. We have exploited a property of a mutant allele of suv3, SUV3-1, that causes, among other effects, a massive increase in the abundance of excised group I introns to clone the wild-type gene by a strategy of colony Northern hybridization. We have determined that the 84-kDa deduced protein product of the suv3 gene, which maps to chromosome XVI, has a typical mitochondrial targeting presequence and additional sequence motifs that suggest that it belongs to a family of ATP-dependent RNA helicases, enzymes whose importance in post-transcriptional and translational events has recently become apparent. We have identified the SUV3-1 mutation as a G----T transversion that creates a Val----Leu substitution in a 10-amino acid block that is highly conserved among ATP-dependent RNA helicases. We discuss some implications of this mutation on the effects of the SUV3-1 allele on mitochondrial RNA metabolism.
线粒体基因表达很大程度上受核基因组产物的作用控制。酵母核基因suv3参与了多种线粒体转录后过程及翻译过程，因此是核-线粒体相互作用中的一个关键控制元件。我们利用了suv3突变等位基因SUV3-1的一个特性，该特性除其他影响外，会导致切除的I类内含子丰度大幅增加，通过菌落Northern杂交策略克隆野生型基因。我们已确定，定位于第十六条染色体的suv3基因推导的84 kDa蛋白质产物具有典型的线粒体靶向前导序列和其他序列基序，这表明它属于ATP依赖性RNA解旋酶家族，这类酶在转录后和翻译事件中的重要性最近已变得明显。我们已确定SUV3-1突变是一个G→T颠换，在一个10个氨基酸的区域产生了Val→Leu替代，该区域在ATP依赖性RNA解旋酶中高度保守。我们讨论了这种突变对SUV3-1等位基因在线粒体RNA代谢方面影响的一些含义。
