Glutaminyl-tRNA Synthetase: From Genetics to Molecular Recognition

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Accurately aminoacylated tRNAs are an a priori requirement for translation of the genetic code. They are synthesized by the aminoacyl‐tRNA synthetases which select both the correct amino acid and tRNA from a total of more than 400 possible combinations. Genetic, biochemical and structural studies have begun to reveal the mechanisms by which this specificity is achieved by Escherichia coli glutaminyl‐tRNA synthetase (GlnRS). Sequence‐specific interactions between GlnRS and tRNAGln determine both the accuracy of tRNA selection and the efficiency of aminoacylation. Thus, amino acid recognition is tRNA‐dependent. Consequently, while a noncognate tRNA may be recognized by GlnRS, the resulting tRNA–enzyme complex displays a considerably reduced affinity for glutamine compared to wild‐type. This mechanism now provides a ready explanation as to why the majority of tRNA mischarging events, including those originally described over 25 years ago for GlnRS, impair cellular viability only to a limited degree.


This article was originally published in Genes to Cells, volume 1, in 1996.


Molecular Biology Society of Japan/Wiley