Springer M, Graffe M, Butler J S, Grunberg-Manago M
Proc Natl Acad Sci U S A. 1986 Jun;83(12):4384-8. doi: 10.1073/pnas.83.12.4384.
The Escherichia coli gene thrS that codes for threonine-tRNA ligase (tRNAThr ligase, formerly threonine-tRNA synthetase, EC 6.1.1.3) has previously been shown to be negatively autoregulated at the level of translation. Here we describe the use of several thrS-lac gene fusions to isolate cis-acting regulatory mutations that increase the translation but not the transcription of the thrS gene. These mutations lead to a total loss of control of repression and derepression of thrS. DNA sequence analysis locates the mutations between 10 and 40 base pairs upstream of the translation initiation codon of thrS and more than 100 base pairs downstream of the transcription initiation site. The mRNA region where these mutations are located shares primary and secondary structure homologies with specific parts of several isoacceptor tRNAThr species. These findings suggest that the ligase regulates its translation by binding to its mRNA at a place that shares some homology with its natural substrate.
编码苏氨酸 - tRNA连接酶（tRNAThr连接酶，以前称为苏氨酸 - tRNA合成酶，EC 6.1.1.3）的大肠杆菌基因thrS先前已被证明在翻译水平上受到负向自我调节。在这里，我们描述了使用几种thrS - lac基因融合来分离顺式作用调节突变，这些突变增加了thrS基因的翻译但不增加其转录。这些突变导致thrS的阻遏和去阻遏控制完全丧失。DNA序列分析将这些突变定位在thrS翻译起始密码子上游10至40个碱基对之间以及转录起始位点下游100多个碱基对处。这些突变所在的mRNA区域与几种同功受体tRNAThr物种的特定部分具有一级和二级结构同源性。这些发现表明，连接酶通过在与其天然底物具有一些同源性的位置与其mRNA结合来调节其翻译。
