The influence of 5′ codon context on translation termination in Saccharomyces cerevisiae
The influence of 5′ codon context on translation termination in Saccharomyces cerevisiae
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DOI：
10.1046/j.1432-1327.1998.2570249.x
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发表时间：
1998-10-01
期刊：
影响因子：
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通讯作者：
Isaksson, LA
中科院分区：
文献类型：
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作者：
Mottagui-Tabar, S;Tuite, MF;Isaksson, LA
使用翻译测定系统在酵母Saccharomyces cerevisiae中研究体内翻译终止。在相对于终止密码子的位置-2-处进行的密码子改变，在释放因子缺陷型（sup 45）突变株中对终止产生3.5倍的影响，与在野生型菌株中观察到的影响一致。-2密码子的影响可能与新生肽中相应氨基酸残基的电荷相关;酸性残基有利于有效终止。因此，新生肽的C-末端在细菌大肠杆菌和酵母S.中均以较小程度影响翻译终止。啤酒。然而，当E. coli和革兰氏阳性菌S.酿酒酵母进行比较。在酵母中改变-1（P-位点）密码子对终止效率的影响有10倍的差异。这种作用可能与新生肽中编码的最后一个氨基酸的任何性质无关。由相同tRNA（AAA/G，GAA/G）读取的同种密码子给出相似的通读值。由不同的同功受体tRNA读取的谷氨酰胺（CAA/G）、谷氨酸（GAA/G）和异亮氨酸（AUA/C）的密码子在每种情况下与终止效率的大约两倍的差异相关。这表明P-位点tRNA能够影响酵母中UGAC的终止。
Translation termination in vivo was studied in the yeast Saccharomyces cerevisiae using a translation-assay system. Codon changes that were made at position -2-relative to the stop codon, gave a 3.5-fold effect on termination in a release-factor-defective (sup45) mutant strain, in line with the effect observed in a wild-type strain. The influence of the -2 codon could be correlated to the charge of the corresponding amino acid residue in the nascent peptide; an acidic residue favoring efficient termination. Thus, the C-terminal end of the nascent peptide influences translation termination both in the bacterium Escherichia coli and to a lesser extent in the yeast S. cerevisiae. However, the sensitivity to the charge of the penultimate amino acid is reversed when the E. coli and S. cerevisiae are compared. Changing -1 (P-site) codons in yeast gave a 10-fold difference in effect on the efficiency of termination. This effect could not be related to any property of the encoded last amino acid in the nascent peptide. Iso-codons read by the same tRNA (AAA/G, GAA/G) gave similar readthrough values. Codons for glutamine (CAA/G), glutamic acid (GAA/G) and isoleucine (AUA/C) that are read by different isoaccepting tRNAs are associated with an approximately twofold difference in each case in termination efficiency. This suggests that the P-site tRNAis able to influence termination at UGAC in yeast.