A Primary Role for Release Factor 3 in Quality Control during Translation Elongation in Escherichia coli

Release factor 3 (RF3) is a GTPase found in a broad range of bacteria where it is thought to play a critical "recycling" role in translation by facilitating the removal of class 1 release factors (RF1 and RF2) from the ribosome following peptide release. More recently, RF3 was shown in vitro to stimulate a retrospective editing reaction on the bacterial ribosome wherein peptides carrying mistakes are prematurely terminated during protein synthesis. Here, we examine the role of RF3 in the bacterial cell and show that the deletion of this gene sensitizes cells to other perturbations that reduce the overall fidelity of protein synthesis. We further document substantial effects on mRNA stability and protein expression using reporter systems, native mRNAs and proteins. We conclude that RF3 plays a primary role in vivo in specifying the fidelity of protein synthesis thus impacting overall protein quantity and quality.