A single sequence context cannot satisfy all non-AUG initiator codons in yeast

BMC Microbiol. 2010 Jul 9;10:188. doi: 10.1186/1471-2180-10-188.


Background: Previous studies in Saccharomyces cerevisiae showed that ALA1 (encoding alanyl-tRNA synthetase) and GRS1 (encoding glycyl-tRNA synthetase) respectively use ACG and TTG as their alternative translation initiator codons. To explore if any other non-ATG triplets can act as initiator codons in yeast, ALA1 was used as a reporter for screening.

Results: We show herein that except for AAG and AGG, all triplets that differ from ATG by a single nucleotide were able to serve as initiator codons in ALA1. Among these initiator codons, TTG, CTG, ACG, and ATT had ~50% initiating activities relative to that of ATG, while GTG, ATA, and ATC had ~20% initiating activities relative to that of ATG. Unexpectedly, these non-AUG initiator codons exhibited different preferences toward various sequence contexts. In particular, GTG was one of the most efficient non-ATG initiator codons, while ATA was essentially inactive in the context of GRS1.

Conclusion: This finding indicates that a sequence context that is favorable for a given non-ATG initiator codon might not be as favorable for another.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alanine-tRNA Ligase / genetics
  • Alanine-tRNA Ligase / metabolism*
  • Amino Acid Sequence
  • Base Sequence
  • Codon, Initiator*
  • Molecular Sequence Data
  • Peptide Chain Initiation, Translational*
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism*


  • Codon, Initiator
  • Saccharomyces cerevisiae Proteins
  • Alanine-tRNA Ligase