Montoya J, Perez-Martos A, Garstka H L, Wiesner R J
Departamento de Bioquimica y Biologia Molecular y Celular, Facultad de Veterinaria, Zaragoza, Spain.
Mol Cell Biochem. 1997 Sep;174(1-2):227-30.
In order to test the hypothesis that mitochondrial transcription factor A (mtTFA) regulates mitochondrial transcription in vivo, mtTFA was overexpressed in HeLa cells and imported into isolated rat liver mitochondria. Five hours after transfection with an eukaryotic expression vector, mitochondrial transcripts for cytochrome-c-oxidase subunit I and 12 S rRNA were increased over controls. In the presence of rat liver mitochondria, the 29 kDa mtTFA, generated by in vitro translation, was processed to a 24 kDa protein which was protected from protease digestion. This demonstrates that mtTFA was imported into the matrix. Incorporation of 32P-UTP into mitochondrial transcripts was stimulated following import of mTFA. We conclude that the intracellular and intramitochondrial concentration of mtTFA, respectively, indeed regulates mitochondrial transcription.
为了验证线粒体转录因子A（mtTFA）在体内调节线粒体转录的假说，在HeLa细胞中过表达mtTFA，并将其导入分离的大鼠肝线粒体。用真核表达载体转染5小时后，细胞色素c氧化酶亚基I和12S rRNA的线粒体转录本比对照增加。在大鼠肝线粒体存在的情况下，体外翻译产生的29kDa mtTFA被加工成24kDa的蛋白质，该蛋白质可免受蛋白酶消化。这表明mtTFA被导入了线粒体基质。导入mTFA后，32P-UTP掺入线粒体转录本的过程受到刺激。我们得出结论，mtTFA在细胞内和线粒体内的浓度确实分别调节线粒体转录。
