Mulero J J, Fox T D
Section of Biochemistry, Molecular and Cell Biology, Cornell University, Ithaca, New York 14853-2703.
Genetics. 1993 Mar;133(3):509-16. doi: 10.1093/genetics/133.3.509.
PET111 is a yeast nuclear gene specifically required for the expression of the mitochondrial gene COX2, encoding cytochrome c oxidase subunit II (coxII). Previous studies have shown that PET111 activates translation of the COX2 mRNA. To map the site of PET111 action we have constructed, in vitro, genes coding for chimeric mRNAs, introduced them into mitochondria by transformation and studied their expression. Translation of a chimeric mRNA with the 612-base 5'-untranslated leader of the COX3 mRNA fused precisely to the structural gene for the coxII-precursor protein is independent of PET111, but does require a COX3 mRNA-specific translational activator known to work on the COX3 5'-leader. This result demonstrates that PET111 is not required for any post-translational step. Translation of a chimeric mRNA with the 54-base 5'-leader of the COX2 mRNA fused precisely to the structural gene for cytochrome c oxidase subunit III was dependent on PET111 activity. These results demonstrate that PET111 acts specifically at a site in the short COX2 5'-leader to activate translation of downstream coding sequences.
PET111是酵母中的一个核基因，是线粒体基因COX2表达所特需的，COX2编码细胞色素c氧化酶亚基II（coxII）。先前的研究表明，PET111可激活COX2 mRNA的翻译。为了确定PET111的作用位点，我们在体外构建了编码嵌合mRNA的基因，通过转化将它们导入线粒体并研究其表达。一种嵌合mRNA，其具有与coxII前体蛋白的结构基因精确融合的COX3 mRNA的612个碱基的5'-非翻译前导序列，其翻译不依赖于PET111，但确实需要一种已知作用于COX3 5'-前导序列的COX3 mRNA特异性翻译激活因子。这一结果表明，PET111在任何翻译后步骤中都不是必需的。一种嵌合mRNA，其具有与细胞色素c氧化酶亚基III的结构基因精确融合的COX2 mRNA的54个碱基的5'-前导序列，其翻译依赖于PET111的活性。这些结果表明，PET111特异性作用于短的COX2 5'-前导序列中的一个位点，以激活下游编码序列的翻译。
