The bacterial toxin RelE displays codon-specific cleavage of mRNAs in the ribosomal A site

Cell. 2003 Jan 10;112(1):131-40. doi: 10.1016/s0092-8674(02)01248-5.


The Escherichia coli relBE operon encodes a toxin-antitoxin pair, RelE-RelB. RelB can reverse inhibition of protein synthesis by RelE in vivo. We have found that although RelE does not degrade free RNA, it cleaves mRNA in the ribosomal A site with high codon specificity. Among stop codons UAG is cleaved with fast, UAA intermediate and UGA slow rate, while UCG and CAG are cleaved most rapidly among sense codons. We suggest that inhibition of protein synthesis by RelE is reversed with the help of tmRNA, and that RelE plays a regulatory role in bacteria during adaptation to poor growth conditions.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Toxins / metabolism*
  • Catalysis
  • Codon*
  • Codon, Terminator
  • Escherichia coli / genetics
  • Escherichia coli Proteins / metabolism*
  • Genes, Bacterial / genetics
  • In Vitro Techniques
  • Models, Genetic
  • Operon
  • Peptide Biosynthesis
  • Protein Biosynthesis
  • Protein Synthesis Inhibitors / pharmacology
  • RNA, Messenger / chemistry
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism*
  • Ribosomal Proteins / metabolism*
  • Suppression, Genetic
  • Time Factors


  • Bacterial Toxins
  • Codon
  • Codon, Terminator
  • Escherichia coli Proteins
  • Protein Synthesis Inhibitors
  • RNA, Messenger
  • RelE protein, E coli
  • Ribosomal Proteins
  • ribosomal protein L7-L12