Endogenous Stochastic Decoding of the CUG Codon by Competing Ser- and Leu-tRNAs in Ascoidea asiatica

Stefanie Mühlhausen, Hans Dieter Schmitt, Kuan Ting Pan, Uwe Plessmann, Henning Urlaub, Laurence D. Hurst, Martin Kollmar

Research output: Contribution to journalArticlepeer-review

16 Citations (SciVal)


Although the "universal" genetic code is now known not to be universal, and stop codons can have multiple meanings, one regularity remains, namely that for a given sense codon there is a unique translation. Examining CUG usage in yeasts that have transferred CUG away from leucine, we here report the first example of dual coding: Ascoidea asiatica stochastically encodes CUG as both serine and leucine in approximately equal proportions. This is deleterious, as evidenced by CUG codons being rare, never at conserved serine or leucine residues, and predominantly in lowly expressed genes. Related yeasts solve the problem by loss of function of one of the two tRNAs. This dual coding is consistent with the tRNA-loss-driven codon reassignment hypothesis, and provides a unique example of a proteome that cannot be deterministically predicted. VIDEO ABSTRACT.

Original languageEnglish
Pages (from-to)2046-2057
Number of pages18
JournalCurrent Biology
Issue number13
Early online date18 Jun 2018
Publication statusPublished - 9 Jul 2018

Bibliographical note

Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.


  • Ascoidea asiatica
  • codon reassignment
  • competing tRNAs
  • CUG codon
  • genetic code
  • proteomics
  • Saccharomycopsis
  • stochastic decoding
  • yeast evolution

ASJC Scopus subject areas

  • General Biochemistry,Genetics and Molecular Biology
  • General Agricultural and Biological Sciences


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