Dong H, Kurland C G
Department of Molecular Biology, Biomedical Center, Uppsala, Sweden.
J Mol Biol. 1995 May 5;248(3):551-61. doi: 10.1006/jmbi.1995.0242.
We have determined whether or not there is a correlation between the accuracy of tRNA selection and the processivity of translation by mutant ribosomes. In our assay the estimation of processivity was made from a system in which transcription is dependent on T7 RNA polymerase in order to eliminate the influence of transcriptional polarity on our measurements. We found that the processivity of translation is reciprocally correlated to the degree with which mutant ribosomes restrict nonsense suppression events. This is observed when transcription is from both T7 RNA polymerase and Escherichia coli RNA polymerase. In other words, we have confirmed the expected correlation between increased accuracy of tRNA selection and decreased processivity of translation. No such monotonic correlation was obtained with ribosome ambiguity (ram) mutants, though all of these were less processive than wild-type ribosomes. In addition, streptomycin was found to simultaneously stimulate tRNA selection errors and processivity of translation for a mutant that is partially dependent on streptomycin. These data suggest that the growth rates of ribosome mutants are significantly decreased by the degree to which their processivity in translation is affected. Furthermore, we suggest that streptomycin dependence is a phenomenon reflecting the interplay of the restrictive mutation and antibiotic on the processivity of translation.
我们已经确定了tRNA选择的准确性与突变核糖体翻译的持续性之间是否存在关联。在我们的实验中，持续性的评估是基于一个转录依赖T7 RNA聚合酶的系统进行的，以便消除转录极性对我们测量结果的影响。我们发现，翻译的持续性与突变核糖体限制无义抑制事件的程度呈负相关。当转录由T7 RNA聚合酶和大肠杆菌RNA聚合酶共同进行时，都能观察到这种现象。换句话说，我们证实了tRNA选择准确性提高与翻译持续性降低之间的预期关联。对于核糖体模糊性（ram）突变体，未获得这种单调相关性，尽管所有这些突变体的持续性都低于野生型核糖体。此外，对于一个部分依赖链霉素的突变体，发现链霉素能同时刺激tRNA选择错误和翻译的持续性。这些数据表明，核糖体突变体的生长速率因其翻译持续性受影响的程度而显著降低。此外，我们认为链霉素依赖性是一种反映限制性突变和抗生素对翻译持续性相互作用的现象。
