How tRNAs dictate nuclear codon reassignments: Only a few can capture non-cognate codons

RNA Biol. 2017 Mar 4;14(3):293-299. doi: 10.1080/15476286.2017.1279785. Epub 2017 Jan 17.

Abstract

mRNA decoding by tRNAs and tRNA charging by aminoacyl-tRNA synthetases are biochemically separated processes that nevertheless in general involve the same nucleotides. The combination of charging and decoding determines the genetic code. Codon reassignment happens when a differently charged tRNA replaces a former cognate tRNA. The recent discovery of the polyphyly of the yeast CUG sense codon reassignment challenged previous mechanistic considerations and led to the proposal of the so-called tRNA loss driven codon reassignment hypothesis. Accordingly, codon capture is caused by loss of a tRNA or by mutations in the translation termination factor, subsequent reduction of the codon frequency through reduced translation fidelity and final appearance of a new cognate tRNA. Critical for codon capture are sequence and structure of the new tRNA, which must be compatible with recognition regions of aminoacyl-tRNA synthetases. The proposed hypothesis applies to all reported nuclear and organellar codon reassignments.

Keywords: Anticodon; Pachysolen tannophilus; codon reassignment; genetic code; tRNA; yeasts.

Publication types

  • Review

MeSH terms

  • Animals
  • Anticodon
  • Codon / genetics*
  • Codon, Terminator
  • Genetic Code
  • Humans
  • Protein Biosynthesis*
  • RNA, Transfer / genetics*
  • Yeasts / genetics
  • Yeasts / metabolism

Substances

  • Anticodon
  • Codon
  • Codon, Terminator
  • RNA, Transfer