Saarma U, Remme J, Ehrenberg M, Bilgin N
Institute of Molecular and Cell Biology, Department of Molecular Biology, Tartu University, Tartu, EE2400, Estonia.
J Mol Biol. 1997 Sep 26;272(3):327-35. doi: 10.1006/jmbi.1997.1254.
Escherichia coli ribosomes with an A to U transversion at nucleotide 1067 of their 23 S rRNA are impaired in their effective association rate constants (kcat/KM) for both EF-Tu and EF-G binding. In addition, the times that EF-G and EF-Tu spend on the ribosome during elongation are significantly increased by the A to U transversion. The U1067 mutation impairs EF-Tu function more than EF-G function. The increase in the time that EF-Tu remains bound to ribosome is caused, both by a slower rate of GTP-hydrolysis in ternary complex and by a slower EF-Tu.GDP release from the mutated ribosomes. There is, at the same time, no change in ribosomal accuracy for aminoacyl-tRNA recognition. With support from these new data we propose that nucleotide 1067 is part of the ribosomal A-site where it directly interacts with both EF-G and EF-Tu.
23 S rRNA核苷酸1067处发生A到U颠换的大肠杆菌核糖体，其与EF-Tu和EF-G结合的有效缔合速率常数（kcat/KM）受损。此外，在延伸过程中，EF-G和EF-Tu在核糖体上停留的时间因A到U颠换而显著增加。U1067突变对EF-Tu功能的损害大于对EF-G功能的损害。EF-Tu与核糖体结合时间的增加，是由三元复合物中GTP水解速率减慢以及EF-Tu.GDP从突变核糖体释放速率减慢共同导致的。与此同时，核糖体对氨酰-tRNA识别的准确性没有变化。基于这些新数据，我们提出核苷酸1067是核糖体A位点的一部分，在该位点它直接与EF-G和EF-Tu相互作用。
