The Length of the 5′ Leader of Escherichia coli tRNA Precursors Influences Bacterial Growth

Based on a computational analysis of the 5′ regions of tRNA-encoding genes, the average length of the 5′ leaders in tRNA precursors in Escherichia coli appears to be 17–18 residues long. An in vivo assay based on tRNA nonsense suppression was developed and used to investigate the function of the 5′ leader of the tRNA precursors on tRNA processing and bacterial growth. Our data indicate that the 5′ leader influences bacterial growth but is surprisingly not absolutely necessary for growth. These findings are consistent with previous in vitro data where it was demonstrated that the 5′ leader plays a role in the interaction with RNase P, the endoribonuclease responsible for removing the 5′ leader in the cell. We discuss the plausible role of the 5′ leader in processing and tRNA gene expression.