Bösl M, Kersten H
Institut für Biochemie, Medizinischen Fakultät, Universität Erlangen-Nürnberg, FRG.
Nucleic Acids Res. 1991 Nov 11;19(21):5863-70. doi: 10.1093/nar/19.21.5863.
The tyrT operon of E. coli and several other tRNA operons of E. coli show striking structural features: they contain repeated sequence units including a 19bp motif resembling the 3' end of the corresponding mature tRNA. A novel RNA, encoded by the repeated sequence of the tyrT operon, was identified. The RNA, characterized by primer extension and Nuclease-S1 analysis, contained 171 nucleotides and terminated with the 19bp motif of the CCA-end of tRNA(1Tyr). The RNA, designated as rtT RNA, is probably released from the primary transcript of tyrT during tRNA processing, it includes the coding capacity for the arginine rich peptide Tpr. Predictions of secondary folding resulted a rather stable RNA structure with a free energy of -44.3kcal/mol. A weak ribosome binding site was found, preceding the second possible AUG initiator codon for Tpr. The comparison of rtT RNA with putative transcripts from the repeated sequences associated with related tRNA genes showed common features with respect to primary structure, arrangement and secondary folding. In E. coli cultures the lag-phase during growth, caused by transient glycine or by isoleucine limitation, was found to be overcome or markedly shortened in the presence of rtT RNA. These and previously reported results suggest a modulatory effect of rtT RNA on stringent response.
大肠杆菌的tyrT操纵子以及大肠杆菌的其他几个tRNA操纵子具有显著的结构特征：它们包含重复序列单元，其中包括一个19bp的基序，类似于相应成熟tRNA的3'末端。通过tyrT操纵子的重复序列编码的一种新型RNA被鉴定出来。通过引物延伸和核酸酶S1分析表征的该RNA包含171个核苷酸，并以tRNA（1Tyr）的CCA末端的19bp基序终止。该RNA被命名为rtT RNA，可能在tRNA加工过程中从tyrT的初级转录本中释放出来，它包含富含精氨酸的肽Tpr的编码能力。二级折叠预测产生了一种相当稳定的RNA结构，自由能为-44.3kcal/mol。在Tpr的第二个可能的AUG起始密码子之前发现了一个弱核糖体结合位点。将rtT RNA与来自相关tRNA基因的重复序列的推定转录本进行比较，发现在一级结构、排列和二级折叠方面具有共同特征。在大肠杆菌培养物中，发现由短暂的甘氨酸或异亮氨酸限制引起的生长滞后期在rtT RNA存在下被克服或显著缩短。这些以及先前报道的结果表明rtT RNA对严谨反应具有调节作用。
