Significant bias against the ACA triplet in the tmRNA sequence of Escherichia coli K-12

Sarah Baik, Koichi Inoue, Ming Ouyang, Masayori Inouye

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


The toxin MazF in Escherichia coli cleaves single-stranded RNAs specifically at ACA sequences. MazF overexpression virtually eliminates all cellular mRNAs to completely block protein synthesis. However, protein synthesis can continue on an mRNA that is devoid of ACA triplets. The finding that ribosomal RNAs remain intact in the face of complete translation arrest suggested a purpose for such preservation. We therefore examined the sequences of all transcribed RNAs to determine if there was any statistically significant bias against ACA. While ACA motifs are absent from tmRNA, 4.5S RNA, and seven of the eight 5S rRNAs, statistical analysis revealed that only for tmRNA was the absence nonrandom. The introduction of single-strand ACAs makes tmRNA highly susceptible to MazF cleavage. Furthermore, analysis of tmRNA sequences from 442 bacteria showed that the discrimination against ACA in tmRNAs was seen mostly in enterobacteria. We propose that the unusual bias against ACA in tmRNA may have coevolved with the acquisition of MazF.

Original languageEnglish (US)
Pages (from-to)6157-6166
Number of pages10
JournalJournal of bacteriology
Issue number19
StatePublished - Oct 2009

All Science Journal Classification (ASJC) codes

  • Microbiology
  • Molecular Biology


Dive into the research topics of 'Significant bias against the ACA triplet in the tmRNA sequence of Escherichia coli K-12'. Together they form a unique fingerprint.

Cite this