title: Deregulation of poly(A) polymerase I in Escherichia coli inhibits protein synthesis and leads to cell death.
abstract: Polyadenylation plays important roles in RNA metabolism in both prokaryotes and eukaryotes. Surprisingly, deregulation of polyadenylation by poly(A) polymerase I (PAP I) in Escherichia coli leads to toxicity and cell death. We show here that mature tRNAs, which are normally not substrates for PAP I in wild-type cells, are rapidly polyadenylated as PAP I levels increase, leading to dramatic reductions in the fraction of aminoacylated tRNAs, cessation of protein synthesis and cell death. The toxicity associated with PAP I is exacerbated by the absence of either RNase T and/or RNase PH, the two major 3' → 5' exonucleases involved in the final step of tRNA 3'-end maturation, confirming their role in the regulation of tRNA polyadenylation. Furthermore, our data demonstrate that regulation of PAP I is critical not for preventing the decay of mRNAs, but rather for maintaining normal levels of functional tRNAs and protein synthesis in E. coli, a function for polyadenylation that has not been observed previously in any organism.
authors.affiliation: Department of Genetics, University of Georgia, Athens, GA 30602, USA.
authors.forename: Bijoy K
authors.initials: BK
authors.lastname: Mohanty
authors.forename: Sidney R
authors.initials: SR
authors.lastname: Kushner
mesh_terms: D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000378:metabolism*; D005095:Exoribonucleases / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D010641:Phenotype; D026723:Polyadenylation; D011062:Polynucleotide Adenylyltransferase / Q000378:metabolism*; D014176:Protein Biosynthesis; D012343:RNA, Transfer / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; D012343:RNA, Transfer; D011062:Polynucleotide Adenylyltransferase; C063643:pcnB protein, E coli; C056502:ribonuclease PH; D005095:Exoribonucleases; C042081:exoribonuclease T