Trudel M, Springer M, Graffe M, Fayat G, Blanquet S, Grunberg-Manago M
Biochim Biophys Acta. 1984 May 15;782(1):10-7. doi: 10.1016/0167-4781(84)90100-3.
The phenylalanyl-tRNA synthetase operon is composed of two adjacent, cotranscribed genes, pheS and pheT, corresponding respectively to the small and large subunit of phenylalanyl-tRNA synthetase. A fusion between the regulatory regions of phenylalanyl-tRNA synthetase operon and the lac structural genes has been constructed to study the regulation of the operon. The pheS,T operon was shown, using the fusion, to be derepressed when phenylalanine concentrations were limiting in a leaky auxotroph mutated in the phenylalanine biosynthetic pathway. Furthermore, a mutational alteration in the phenylalanyl-tRNA synthetase gene, bradytrophic for phenylalanine, was also found to be derepressed under phenylalanine starvation. These results indicate that the pheS,T operon is derepressed when the level of tRNAPhe aminoacylation is lowered. By analogy with other well-studied amino acid biosynthetic operons known to be controlled by attenuation, these in vivo results indicate that phenylalanyl-tRNA synthetase levels are controlled by an attenuation-like mechanism.
苯丙氨酰 - tRNA合成酶操纵子由两个相邻的共转录基因pheS和pheT组成，它们分别对应苯丙氨酰 - tRNA合成酶的小亚基和大亚基。为了研究该操纵子的调控，构建了苯丙氨酰 - tRNA合成酶操纵子的调控区与lac结构基因之间的融合体。利用该融合体发现，在苯丙氨酸生物合成途径中发生渗漏型营养缺陷突变且苯丙氨酸浓度受到限制时，pheS,T操纵子会去阻遏。此外，还发现苯丙氨酰 - tRNA合成酶基因中对苯丙氨酸营养生长缓慢的突变改变在苯丙氨酸饥饿条件下也会去阻遏。这些结果表明，当tRNAPhe氨酰化水平降低时，pheS,T操纵子会去阻遏。与其他已知受衰减作用控制的经过充分研究的氨基酸生物合成操纵子类似，这些体内实验结果表明苯丙氨酰 - tRNA合成酶水平受类似衰减的机制控制。
