An RNA-seq method for defining endoribonuclease cleavage specificity identifies dual rRNA substrates for toxin MazF-mt3

Nat Commun. 2014 Apr 8;5:3538. doi: 10.1038/ncomms4538.


Toxin-antitoxin (TA) systems are widespread in prokaryotes. Among these, the mazEF TA system encodes an endoribonucleolytic toxin, MazF, that inhibits growth by sequence-specific cleavage of single-stranded RNA. Defining the physiological targets of a MazF toxin first requires the identification of its cleavage specificity, yet the current toolkit is antiquated and limited. We describe a rapid genome-scale approach, MORE (mapping by overexpression of an RNase in Escherichia coli) RNA-seq, for defining the cleavage specificity of endoribonucleolytic toxins. Application of MORE RNA-seq to MazF-mt3 from Mycobacterium tuberculosis reveals two critical ribosomal targets-the essential, evolutionarily conserved helix/loop 70 of 23S rRNA and the anti-Shine-Dalgarno (aSD) sequence of 16S rRNA. Our findings support an emerging model where both ribosomal and messenger RNAs are principal targets of MazF toxins and suggest that, as in E. coli, removal of the aSD sequence by a MazF toxin modifies ribosomes to selectively translate leaderless mRNAs in M. tuberculosis.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Bacterial Proteins / metabolism*
  • DNA-Binding Proteins / metabolism
  • Endoribonucleases / metabolism*
  • Escherichia coli Proteins / metabolism
  • Escherichia coli*
  • Mycobacterium tuberculosis*
  • Protein Structure, Secondary
  • RNA Cleavage
  • RNA, Messenger / metabolism*
  • RNA, Ribosomal, 16S / metabolism*
  • RNA, Ribosomal, 23S / metabolism*
  • Ribonucleases / metabolism
  • Sequence Analysis, RNA
  • Toxins, Biological


  • Bacterial Proteins
  • DNA-Binding Proteins
  • Escherichia coli Proteins
  • MazF protein, E coli
  • RNA, Messenger
  • RNA, Ribosomal, 16S
  • RNA, Ribosomal, 23S
  • Toxins, Biological
  • Endoribonucleases
  • MazF protein, Mycobacterium tuberculosis
  • Ribonucleases