SUF12 suppressor protein of yeast. A fusion protein related to the EF-1 family of elongation factors.
SUF12 suppressor protein of yeast. A fusion protein related to the EF-1 family of elongation factors.
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DOI：
10.1016/0022-2836(88)90301-4
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发表时间：
1988-02
影响因子：
5.6
通讯作者：
Patricia G. Wilson;M. Culbertson
中科院分区：
文献类型：
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作者：
Patricia G. Wilson;M. Culbertson
suf 12位点的突变在酿酒酵母中被分离为甘氨酸（GGX）和脯氨酸（CCX）密码子中+1移码突变以及UGA和UAG无义突变的基因外抑制子。为了鉴定SUF 12在翻译中的功能，并了解suf 12介导的误读和翻译移码之间的关系，我们通过互补从着丝粒质粒文库中分离了一个SUF 12+克隆。SUF 12+是一个必需的单拷贝基因，与全能抑制基因SUP 35+相同。SUF 12+转录本含有一个开放阅读框，编码88× 10 3 M的r蛋白。密码子使用模式和转录本丰度表明SUF 12+不是高表达基因。线性SUFI 2氨基酸序列表明，SUFI 2已经进化为独特的N-末端结构域融合到与EF-1家族延伸因子基本上共线性同源的结构域的融合蛋白。从内部氨基酸254开始，SUF 12蛋白和酵母EF-1α之间的同源性（36%的同一性; 65%的保守取代）比酵母EF-1α和大肠杆菌EF-Tu之间的同源性更广泛。SUF 12 EF-1α同源性最广泛的区域是EF-1家族中保守的区域，包括涉及GTP和tRNA结合的结构域。很明显，SUF 12和EF-1α在功能上并不等同，因为两者在体内都是必需的。SUF 12的N-末端结构域是独特的，并且可以部分地反映这些蛋白质之间的功能区别。这些结构域表现出不寻常的氨基酸组成和广泛的重复结构。suf 12-null SUF 12+杂合子的行为表明suf 12是共显性表达的，并表明suf 12等位基因特异性抑制可能来自功能不同的突变蛋白，而不是残余野生型SUF 12+活性的变化。我们提出了一个模型的suf 12介导的移码和无义抑制，是基于一个主要的缺陷，在正常的过程中的密码子识别。
Mutations at the suf12 locus were isolated in Saccharomyces cerevisiae as extragenic suppressors of+ 1 frameshift mutations in glycine (GGX) and proline (CCX) codons, as well as UGA and UAG nonsense mutations. To identify the SUF12 function in translation and to understand the relationship between suf12-mediated misreading and translational frameshifting, we have isolated an SUF12+ clone from a centromeric plasmid library by complementation. SUF12+ is an essential, single-copy gene that is identical with the omnipotent suppressor gene SUP35+. The 2.3× 10 3 base SUF12+ transcript contains an open reading frame sufficient to encode a 88× 10 3 M r protein. The pattern of codon usage and transcript abundance suggests that SUF12+ is not a highly expressed gene. The linear SUFI2 amino acid sequence suggests that SUFI2 has evolved as a fusion protein of unique N-terminal domains fused to domains that exhibit essentially co-linear homology to the EF-1 family of elongation factors. Beginning internally at amino acid 254, homology is more extensive between the SUF12 protein and EF-1α of yeast (36% identity; 65% with conservative substitutions) than between EF-1α of yeast and EF-Tu of Escherichia coli. The most extensive regions of SUF12 EF-1α homology are those regions that have been conserved in the EF-1 family, including domains involved in GTP and tRNA binding. It is clear that SUF12 and EF-1α are not functionally equivalent, since both are essential in vivo. The N-terminal domains of SUF12 are unique and may reflect, in part, the functional distinction between these proteins. These domains exhibit unusual amino acid composition and extensive repeated structure. The behavior of suf12-null SUF12+ heterozygotes indicates that suf12 is co-dominantly expressed and suggests that suf12 allele-specific suppression may result from functionally distinct mutant proteins rather than variation in residual wild-type SUF12+ activity. We propose a model of suf12-mediated frameshift and nonsense suppression that is based on a primary defect in the normal process of codon recognition.