A processed noncoding RNA regulates an altruistic bacterial antiviral system

Nat Struct Mol Biol. 2011 Feb;18(2):185-90. doi: 10.1038/nsmb.1981. Epub 2011 Jan 16.


The ≥ 10³⁰ bacteriophages on Earth relentlessly drive adaptive coevolution, forcing the generation of protective mechanisms in their bacterial hosts. One such bacterial phage-resistance system, ToxIN, consists of a protein toxin (ToxN) that is inhibited in vivo by a specific RNA antitoxin (ToxI); however, the mechanisms for this toxicity and inhibition have not been defined. Here we present the crystal structure of the ToxN-ToxI complex from Pectobacterium atrosepticum, determined to 2.75-Å resolution. ToxI is a 36-nucleotide noncoding RNA pseudoknot, and three ToxI monomers bind to three ToxN monomers to generate a trimeric ToxN-ToxI complex. Assembly of this complex is mediated entirely through extensive RNA-protein interactions. Furthermore, a 2'-3' cyclic phosphate at the 3' end of ToxI, and catalytic residues, identify ToxN as an endoRNase that processes ToxI from a repetitive precursor but is regulated by its own catalytic product.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / chemistry
  • Bacterial Proteins / metabolism*
  • Bacteriophages / physiology
  • Base Sequence
  • Crystallography, X-Ray
  • Endoribonucleases / chemistry
  • Endoribonucleases / metabolism
  • Host-Pathogen Interactions
  • Models, Molecular
  • Molecular Sequence Data
  • Nucleic Acid Conformation
  • Pectobacterium / chemistry
  • Pectobacterium / genetics*
  • Pectobacterium / physiology*
  • Pectobacterium / virology
  • RNA, Bacterial / chemistry
  • RNA, Bacterial / metabolism*
  • RNA, Untranslated / chemistry*
  • RNA, Untranslated / metabolism*


  • Bacterial Proteins
  • RNA, Bacterial
  • RNA, Untranslated
  • Endoribonucleases