Cummins C M, Donahue T F, Culbertson M R
Proc Natl Acad Sci U S A. 1982 Jun;79(11):3565-9. doi: 10.1073/pnas.79.11.3565.
To elucidate the molecular mechanism of frameshift suppression by the SUF2 gene of yeast, the sequences of DNA fragments carrying the SUF2-1 and suf2+ alleles of the gene and surrounding regions have been determined. Comparison of the suppressor and wild-type sequences indicates that the SUF2 gene product is a proline tRNA. Disregarding possible base modifications, we find that the wild-type suf2+ anticodon of the tRNA inferred from the DNA sequence is 3'-GGA-5'. The SUF2-1 mutation represents the insertion of a G-C base pair at a position in the gene that corresponds to the anticodon loop of the tRNA. Replacement of the wild-type suf2+ anticodon by a 3'-GGGA-5' fourbase anticodon enables the SUF2-1 tRNA to suppress the 5'-CCCU-3' four-base codons generated as the result of the his4-712 and his4-713 frameshift mutations. This nontriplet codon-anticodon interaction restores the correct reading frame and allows synthesis of a functional his4 protein.
为阐明酵母SUF2基因移码抑制的分子机制，已确定携带该基因的SUF2 - 1和suf2 +等位基因及周边区域的DNA片段序列。抑制子序列与野生型序列的比较表明，SUF2基因产物是一种脯氨酸tRNA。不考虑可能的碱基修饰，我们发现从DNA序列推断出的野生型suf2 + tRNA反密码子是3'-GGA-5'。SUF2 - 1突变代表在基因中对应于tRNA反密码子环的位置插入了一个G - C碱基对。用3'-GGGA-5'四碱基反密码子取代野生型suf2 +反密码子，使SUF2 - 1 tRNA能够抑制因his4 - 712和his4 - 713移码突变产生的5'-CCCU-3'四碱基密码子。这种非三联体密码子 - 反密码子相互作用恢复了正确的阅读框，并允许合成功能性的his4蛋白。
