Arabidopsis IRE1 catalyses unconventional splicing of bZIP60 mRNA to produce the active transcription factor

Sci Rep. 2011;1:29. doi: 10.1038/srep00029. Epub 2011 Jul 1.


IRE1 plays an essential role in the endoplasmic reticulum (ER) stress response in yeast and mammals. We found that a double mutant of Arabidopsis IRE1A and IRE1B (ire1a/ire1b) is more sensitive to the ER stress inducer tunicamycin than the wild-type. Transcriptome analysis revealed that genes whose induction was reduced in ire1a/ire1b largely overlapped those in the bzip60 mutant. We observed that the active form of bZIP60 protein detected in the wild-type was missing in ire1a/ire1b. We further demonstrated that bZIP60 mRNA is spliced by ER stress, removing 23 ribonucleotides and therefore causing a frameshift that replaces the C-terminal region of bZIP60 including the transmembrane domain (TMD) with a shorter region without a TMD. This splicing was detected in ire1a and ire1b single mutants, but not in the ire1a/ire1b double mutant. We conclude that IRE1A and IRE1B catalyse unconventional splicing of bZIP60 mRNA to produce the active transcription factor.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / genetics
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / genetics*
  • Arabidopsis Proteins / metabolism*
  • Basic-Leucine Zipper Transcription Factors / genetics*
  • Biocatalysis*
  • Polymerase Chain Reaction
  • Protein Kinases / metabolism*
  • RNA Splicing*
  • RNA, Messenger / genetics*
  • Transcription Factors / metabolism*
  • Transcriptome
  • Tunicamycin / pharmacology


  • Arabidopsis Proteins
  • Basic-Leucine Zipper Transcription Factors
  • RNA, Messenger
  • Transcription Factors
  • bZIP60 protein, Arabidopsis
  • Tunicamycin
  • Protein Kinases
  • Ire1-2 protein, Arabidopsis