Peptidyl-tRNA hydrolase and its critical role in protein biosynthesis

Peptidyl-tRNA hydrolase (Pth) releases tRNA from peptidyl-tRNA by cleaving the ester bond between the peptide and the tRNA. Genetic analyses using Escherichia coli harbouring temperature-sensitive Pth have identified a number of translation factors involved in peptidyl-tRNA release. Accumulation of peptidyl-tRNA in the cells leads to depletion of aminoacyl-tRNA pools and halts protein biosynthesis. Thus, it is vital for cells to maintain Pth activity to deal with the pollution of peptidyl-tRNAs generated during the initiation, elongation and termination steps of protein biosynthesis. Interestingly, while eubacteria possess a single class of peptidyl-tRNA hydrolase, eukaryotes possess several such activities, making Pth a potential drug target to control eubacterial infections. This review discusses the aspects of Pth that relate to its history and biochemistry and its physiological connections with various cellular factors.