Ribosomal RNA and peptidyl-tRNA hydrolase: a peptide chain termination model for lambda bar RNA inhibition.

We propose here a model to explain the inhibition of bacteriophage lambda (lambda) vegetative growth and the killing of E coli cells defective in peptidyl-tRNA hydrolase (Pth) by lambda bar RNA. The model suggests that bar RNA, which contains a characteristic UGA triplet, base-pairs in an anti-parallel fashion with the 1199-1205 region of E coli 16S rRNA. In doing so, it prevents the required functioning of that region of 16S rRNA in UGA-specific peptide chain termination. Pth is implicated in peptide chain termination because a defect in Pth is required for the achievement of the bar RNA inhibitory effects. We make certain predictions that flow from the model, predictions involving suppression of nonsense mutations, and present preliminary experimental results that demonstrate the fulfillment of those predictions.