Position-dependent termination and widespread obligatory frameshifting in Euplotes translation

Nat Struct Mol Biol. 2017 Jan;24(1):61-68. doi: 10.1038/nsmb.3330. Epub 2016 Nov 21.


The ribosome can change its reading frame during translation in a process known as programmed ribosomal frameshifting. These rare events are supported by complex mRNA signals. However, we found that the ciliates Euplotes crassus and Euplotes focardii exhibit widespread frameshifting at stop codons. 47 different codons preceding stop signals resulted in either +1 or +2 frameshifts, and +1 frameshifting at AAA was the most frequent. The frameshifts showed unusual plasticity and rapid evolution, and had little influence on translation rates. The proximity of a stop codon to the 3' mRNA end, rather than its occurrence or sequence context, appeared to designate termination. Thus, a 'stop codon' is not a sufficient signal for translation termination, and the default function of stop codons in Euplotes is frameshifting, whereas termination is specific to certain mRNA positions and probably requires additional factors.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Euplotes / genetics*
  • Euplotes / metabolism
  • Frameshift Mutation
  • Peptide Chain Termination, Translational
  • Proteome / genetics
  • Proteome / metabolism
  • Protozoan Proteins / genetics
  • Protozoan Proteins / metabolism
  • Transcriptome*


  • Proteome
  • Protozoan Proteins