cis- and trans-acting suppressors of a translation initiation defect at the cyc1 locus of Saccharomyces cerevisiae.
cis- and trans-acting suppressors of a translation initiation defect at the cyc1 locus of Saccharomyces cerevisiae.
复制标题
酿酒酵母 cyc1 位点翻译起始缺陷的顺式和反式作用抑制因子。
DOI：
10.1093/genetics/132.1.97
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发表时间：
1992
期刊：
影响因子：
3.3
通讯作者：
Hampsey,M
中科院分区：
文献类型：
--
作者：
Pinto,I;Na,JG;Sherman,F;Hampsey,M
酿酒酵母的cyc 1 -362突变体由于在cyc 1转录的前导区中启动短开放阅读框（uORF）的异常ATG密码子而缺乏iso-1-细胞色素c。我们已经分离出cyc 1 -362的功能回复突变体，并对其进行了表征，以确定可以抑制uORF作用的顺式和反式作用因子。遗传和DNA序列分析确定了三类回复突变体：（i）在上游ATG（uATG）中获得点突变，将iso-1-细胞色素c恢复到正常水平的回复突变体;（ii）用C或T取代相对于uATG的-1位的正常A残基，将iso-1-细胞色素c的产量从正常的约2%提高到6%（C）或10%（T），表明紧接在起始密码子之前的核苷酸可以影响AUG起始密码子识别的效率，并且在该位点嘌呤比嘧啶更优选;和（iii）将异-1-细胞色素c表达增强至正常的10-40%同时保留uATG的基因外抑制剂。这些抑制因子由五个不同的基因代表，命名为sua 1-sua 4和sua 6。与先前描述的sua 7和sua 8抑制子相反，它们不通过影响cyc 1转录起始位点选择来补偿uATG。潜在的抑制机制进行了讨论。
The cyc1-362 mutant of Saccharomyces cerevisiae is deficient in iso-1-cytochrome c as a consequence of an aberrant ATG codon that initiates a short open reading frame (uORF) in the cyc1 transcribed leader region. We have isolated and characterized functional revertants of cyc1-362 in an effort to define cis- and trans-acting factors that can suppress the effect of the uORF. Genetic and DNA sequence analyses have defined three classes of revertants: (i) those that acquired point mutations in the upstream ATG (uATG), restoring iso-1-cytochrome c to its normal level; (ii) substitution of the normal A residue at position -1 relative to the uATG by either C or T, enhancing iso-1-cytochrome c production from approximately 2% to 6% (C) or 10% (T) of normal, indicating that the nucleotide immediately preceding the initiator codon can affect the efficiency of AUG start codon recognition and that purines are preferred over pyrimidines at this site; and (iii) extragenic suppressors that enhance iso-1-cytochrome c expression to 10-40% of normal while retaining the uATG. These suppressors are represented by five different genes, designated sua1-sua4 and sua6. In contrast to the previously described sua7 and sua8 suppressors, they do not compensate for the uATG by affecting cyc1 transcription start site selection. Potential suppressor mechanisms are discussed.