Arabidopsis IRE1 catalyses unconventional splicing of bZIP60 mRNA to produce the active transcription factor
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Updated: May 24, 2026

Chromatin Immunoprecipitation Assay for the Identification of Arabidopsis Protein-DNA Interactions In Vivo
Published on: January 14, 2016
Yukihiro Nagashima1, Kei-Ichiro Mishiba, Eiji Suzuki
1Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-1 Gakuencho, Nakaku, Sakai, Osaka, 599-8531, Japan.
Abstract:
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.
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