Amber mutations in ribosome recycling factors of Escherichia coli and Thermus thermophilus: evidence for C‐terminal modulator element

Open Access
Publisher Website
Google Scholar
Abstract
Ribosome recycling factor, referred to as RRF, is essential for bacterial growth because of its activity of decomposition of the post‐termination complex of the ribosome after release of polypeptides. In this study, we isolated a conditionally lethal amber mutation, named frr‐3, in the Escherichia coli RRF gene at amino acid position 161, showing that the truncation of the C‐terminal 25 amino acids of RRF is lethal to E. coli. An RRF gene cloned from Thermus thermophilus, whose protein is 44% identical and 68% similar to E. coli RRF, failed to complement the frr‐3(Am) allele. However, truncation of the C‐terminal five amino acids conferred intergeneric complementation activity on T. thermophilus RRF, demonstrating the modulator activity of the C‐terminal tail. Rapid purification of T. thermophilus RRF was achieved by T7‐RNA polymerase‐driven overexpression for crystallography.