In vivo formation of glutamyl-tRNAGln in Escherichia coli by heterologous glutamyl-tRNA synthetases

Abstract Two types of glutamyl-tRNA synthetase exist: the discriminating enzyme (D-GluRS) forms only Glu-tRNA Glu , while the non-discriminating one (ND-GluRS) also synthesizes Glu-tRNA Gln , a required intermediate in protein synthesis in many organisms (but not in Escherichia coli ). Testing the capacity to complement a thermosensitive E. coli gltX mutant and to suppress an E. coli trpA49 missense mutant we examined the properties of heterologous gltX genes. We demonstrate that while Acidithiobacillus ferrooxidans GluRS1 and Bacillus subtilis Q373R GluRS form Glu-tRNA Glu , A. ferrooxidans and Helicobacter pylori GluRS2 form Glu-tRNA Gln in E. coli in vivo.