Translation misreading in lacZ gene in Escherichia coli

Misreading error may happen during messenger RNA translation in the ribosomal A site when there is a mismatch between the codon of mRNA and the anticodon of tRNA. Several studies have used different methods and reported varying error rates, making comparisons difficult. In this study I have developed more accurate estimates for error rates in E.coli, studying mutations affecting glutamic acid 537 (E537) and histidine 391 (H391), in the active site of the enzyme ?-galactosidase. Most mutations at the E537 (H391) codon reduce enzyme activity to 3-5 x 10-5 (4-9 x 10-5) the level of wild type. Some mutants, however, have much higher activity, and I hypothesized that this is due to misreading by tRNAGLU and . My study reports on the missense error rates of several near-cognate codons in these two residues. I also used aminoglycoside antibiotics and ribosomal protein mutations (S4, S5 and S12) to study their effects on these near and non-cognate codons and found that they affect misreading on only some near-cognate codons. These results suggest that the effect of these ribosomal protein mutations and aminoglycoside antibiotics in translation misreading are less general than has been previously reported