Buck M, Griffiths E
Nucleic Acids Res. 1982 Apr 24;10(8):2609-24. doi: 10.1093/nar/10.8.2609.
E. coli growing in the presence of iron-binding proteins produced tRNAtrp and tRNAphe molecules containing i6A instead of ms2i6A adjacent to the anticodon. These undermodified tRNAs functioned less efficiently than the fully modified molecules when translating synthetic polynucleotides containing contiguous codons in an in vitro system, but did not limit the translation of MS2 RNA. We examined the possibility that the altered tRNAs with lowered translational efficiencies could relieve transcription termination at the trp and phe attenuators and lead to increased operon expression under iron restricted conditions. Using trpR mutants we found that there was indeed greater expression of the trp operon during iron restricted growth. This increase was attributable solely to the tRNA alteration induced by iron restriction.
在存在铁结合蛋白的情况下生长的大肠杆菌产生了tRNAtrp和tRNAphe分子，这些分子在反密码子相邻位置含有i6A而非ms2i6A。当在体外系统中翻译含有连续密码子的合成多核苷酸时，这些修饰不足的tRNA的功能效率低于完全修饰的分子，但并不限制MS2 RNA的翻译。我们研究了翻译效率降低的改变型tRNA是否能够缓解色氨酸和苯丙氨酸衰减子处的转录终止，并导致在铁限制条件下操纵子表达增加的可能性。使用trpR突变体，我们发现在铁限制生长期间色氨酸操纵子确实有更高的表达。这种增加完全归因于铁限制诱导的tRNA改变。
