Amino-terminal extension generated from an upstream AUG codon increases the efficiency of mitochondrial import of yeast N2,N2-dimethylguanosine-specific tRNA methyltransferases.
Amino-terminal extension generated from an upstream AUG codon increases the efficiency of mitochondrial import of yeast N2,N2-dimethylguanosine-specific tRNA methyltransferases.
复制标题
由上游 AUG 密码子产生的氨基末端延伸提高了酵母 N2,N2-二甲基鸟苷特异性 tRNA 甲基转移酶的线粒体输入效率。
DOI：
10.1128/mcb.9.4.1611-1620.1989
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发表时间：
1989
影响因子：
5.3
通讯作者：
Martin,NC
中科院分区：
文献类型：
--
作者：
Ellis,SR;Hopper,AK;Martin,NC
Fusions between theTRM1gene ofSaccharomyces cerevisiaeandCOXIVorDHFRwere made to examine the mitochondrial targeting signals ofN2,N2-dimethylguanosine-specific tRNA methyltransferase [tRNA (m22G)dimethyltransferase]. This enzyme is responsible for the modification of both mitochondrial and cytoplasmic tRNAs. We have previously shown that two forms of the enzyme are translated from two in-frame ATGs in this gene, that they differ by a 16-amino-acid amino-terminal extension, and that both the long and short forms are imported into mitochondria. Results of studies to test the ability of variousTRM1sequences to serve as surrogate mitochondrial targeting signals for passenger protein import in vitro and in vivo showed that the most efficient signal derived from tRNA (m22G)dimethyltransferase included a combination of sequences from both the amino-terminal extension and the amino terminus of the shorter form of the enzyme. The amino-terminal extension itself did not serve as an independent mitochondrial targeting signal, whereas the amino terminus of the shorter form of tRNA (m22G)dimethyltransferase did function in this regard, albeit inefficiently. We analyzed the first 48 amino acids of tRNA (m22G)dimethyltransferase for elements of primary and secondary structure shared with other known mitochondrial targeting signals. The results lead us to propose that the most efficient signal spans the area around the second ATG ofTRM1and is consistent with the idea that there is a mitochondrial targeting signal present at the amino terminus of the shorter form of the enzyme and that the amino-terminal extension augments this signal by extending it to form a larger, more efficient mitochondrial targeting signal.
