New Insights into the Relationship between tRNA Processing and Polyadenylation in Escherichia coli

The majority of transcripts in E. coli undergo post-transcriptional addition of poly(A) tails by PAP I. Recent studies suggest that in vivo 79/86 pre-tRNA species undergo PAP I-dependent polyadenylation to some extent prior to final 3′ end maturation. In wild-type E. coli mature tRNAs are generally not polyadenylated due to higher levels of 3′ → 5′ tRNA-processing exonucleases compared with PAP I, which favors aminoacylation by aminoacyl-tRNA synthetases. Unregulated PAP I expression results in the polyadenylation of mature tRNAs, hindering aminoacylation by aminoacyl-tRNA synthetases, leading to inhibition of protein synthesis and cell death