Dyson M R, Mandal N, RajBhandary U L
Institute of Cell and Molecular Biology, University of Edinburgh, UK.
Biochimie. 1993;75(12):1051-60. doi: 10.1016/0300-9084(93)90004-c.
Through functional studies of mutant tRNAs, we have identified sequence and/or structural features important for specifying the many distinctive properties of E coli initiator tRNA. Many of the mutant tRNAs contain an anticodon sequence change from CAU-->CUA and are now substrates for E coli glutaminyl-tRNA synthetase (GlnRS). We describe here the effect of further mutating the discriminator base 73 and nucleotide 72 at the end of the acceptor stem on: i) recognition of the mutant tRNAs by E coli GlnRS; ii) recognition by E coli methionyl-tRNA transformylase; and iii) activity of the mutant tRNAs in initiation in E coli. For GlnRS recognition, our results are, in general, consistent with interactions found in the crystal structure of the E coli GlnRS-glutamine tRNA complex. The results also support our previous conclusion that formylation of initiator tRNA is important for its function in initiation.
通过对突变tRNA的功能研究，我们确定了对指定大肠杆菌起始tRNA的许多独特特性至关重要的序列和/或结构特征。许多突变tRNA的反密码子序列从CAU变为CUA，现在是大肠杆菌谷氨酰胺tRNA合成酶（GlnRS）的底物。我们在此描述进一步突变受体茎末端的判别碱基73和核苷酸72对以下方面的影响：i）大肠杆菌GlnRS对突变tRNA的识别；ii）大肠杆菌甲硫氨酰-tRNA转甲酰基酶的识别；iii）突变tRNA在大肠杆菌起始过程中的活性。对于GlnRS识别，我们的结果总体上与大肠杆菌GlnRS-谷氨酰胺tRNA复合物晶体结构中发现的相互作用一致。这些结果也支持我们之前的结论，即起始tRNA的甲酰化对其起始功能很重要。
