Viral evasion of a bacterial suicide system by RNA-based molecular mimicry enables infectious altruism

PLoS Genet. 2012;8(10):e1003023. doi: 10.1371/journal.pgen.1003023. Epub 2012 Oct 18.


Abortive infection, during which an infected bacterial cell commits altruistic suicide to destroy the replicating bacteriophage and protect the clonal population, can be mediated by toxin-antitoxin systems such as the Type III protein-RNA toxin-antitoxin system, ToxIN. A flagellum-dependent bacteriophage of the Myoviridae, ΦTE, evolved rare mutants that "escaped" ToxIN-mediated abortive infection within Pectobacterium atrosepticum. Wild-type ΦTE encoded a short sequence similar to the repetitive nucleotide sequence of the RNA antitoxin, ToxI, from ToxIN. The ΦTE escape mutants had expanded the number of these "pseudo-ToxI" genetic repeats and, in one case, an escape phage had "hijacked" ToxI from the plasmid-borne toxIN locus, through recombination. Expression of the pseudo-ToxI repeats during ΦTE infection allowed the phage to replicate, unaffected by ToxIN, through RNA-based molecular mimicry. This is the first example of a non-coding RNA encoded by a phage that evolves by selective expansion and recombination to enable viral suppression of a defensive bacterial suicide system. Furthermore, the ΦTE escape phages had evolved enhanced capacity to transduce replicons expressing ToxIN, demonstrating virus-mediated horizontal transfer of genetic altruism.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacteriophages / genetics*
  • Bacteriophages / ultrastructure
  • Base Sequence
  • Biological Evolution
  • DNA, Viral / chemistry
  • DNA, Viral / genetics
  • Gene Expression
  • Gene Order
  • Genome, Viral
  • Molecular Docking Simulation
  • Molecular Mimicry*
  • Molecular Sequence Data
  • Mutation
  • Nucleic Acid Conformation
  • Pectobacterium / genetics*
  • Pectobacterium / virology*
  • Protein Conformation
  • Quantitative Trait Loci
  • RNA, Bacterial / genetics*
  • Sequence Alignment
  • Toxins, Biological / chemistry
  • Toxins, Biological / genetics
  • Toxins, Biological / metabolism
  • Transduction, Genetic


  • DNA, Viral
  • RNA, Bacterial
  • Toxins, Biological