Mitochondrial translation of Saccharomyces cerevisiae COX2 mRNA is controlled by the nucleotide sequence specifying the pre-Cox2p leader peptide
Mitochondrial translation of Saccharomyces cerevisiae COX2 mRNA is controlled by the nucleotide sequence specifying the pre-Cox2p leader peptide
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DOI：
10.1128/mcb.21.7.2359-2372.2001
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发表时间：
2001-04-01
影响因子：
5.3
通讯作者：
Fox, TD
中科院分区：
文献类型：
--
作者：
Bonnefoy, N;Bsat, N;Fox, TD
编码酵母细胞色素氧化酶亚基II（Cox2p）的线粒体基因指定具有15个氨基酸的前导肽的前体蛋白。已知缺失整个前导肽编码区可阻断Cox2p的转录后积累。在这里，我们在体内研究了前Cox2p前导肽和编码它的mRNA序列在线粒体报告基因ARG8（m）表达中的作用，ARG8（m）融合到COX2的第91个密码子，我们在编码序列中发现了控制翻译的拮抗元件：阳性元件包括指定前导肽的前14个密码子中的序列，而阴性元件似乎在密码子15至91内。在cox 2：：ARG 8（m）报告基因和COX 2本身中，前导肽编码区内的部分缺失、点突变和局部移码。令人惊讶的是，指定前导肽的前六个密码子的mRNA序列在正向控制翻译中起重要作用，而前导肽本身的氨基酸序列相对不受约束。两个部分阻断翻译的突变可以通过附近的序列取代来抑制，这些序列取代削弱了预测的茎结构，并且通过过度产生COX2 mRNA特异性翻译激活因子Pet111p或大亚基线粒体核糖体蛋白MrpL36p来抑制。我们认为，嵌入翻译的COX 2 mRNA序列中的调节元件可能与反式作用因子一起在将新生前Cox 2p的调节合成与其在线粒体内膜中的插入偶联中发挥作用。
The mitochondrial gene encoding yeast cytochrome oxidase subunit II (Cox2p) specifies a precursor protein with a 15-amino-acid leader peptide. Deletion of the entire leader peptide coding region is known to block Cox2p accumulation posttranscriptionally. Here, we examined in vivo the role of the pre-Cox2p leader peptide and the mRNA sequence that encodes it in the expression of a mitochondrial reporter gene, ARG8(m), fused to the 91st codon of COX2, We found within the coding sequence antagonistic elements that control translation: the positive element includes sequences in the first 14 codons specifying the leader peptide, while the negative element appears to be,within codons 15 to 91. Partial deletions, point mutations, and local frameshifts within the leader peptide coding region were placed in both the cox2::ARG8(m) reporter and in COX2 itself. Surprisingly, the mRNA sequence of the first six codons specifying the leader peptide plays an important role in positively controlling translation, while the amino acid sequence of the leader peptide itself is relatively unconstrained. Two mutations that partially block translation can be suppressed by nearby sequence substitutions that weaken a predicted stem structure and by overproduction of either the COX2 mRNA-specific translational activator Pet111p or the large-subunit mitochondrial ribosomal protein MrpL36p. We propose that regulatory elements embedded in the translated COX2 mRNA sequence could play a role, together with trans-acting factors, in coupling regulated synthesis of nascent pre-Cox2p to its insertion in the mitochondrial inner membrane.