BLISTER-regulated vegetative growth is dependent on the protein kinase domain of ER stress modulator IRE1A in Arabidopsis thaliana
Fig 7
A working model for IRE1-mediated growth regulation in BLI mutant plants.
In the presence of BLISTER (BLI) in wildtype (WT) plants, BLI may directly or indirectly inhibit IRE1A activation and clustering. In the absence of BLI in bli mutant plants, the inhibitor is removed and IRE1A is activated. The RNase activity of IRE1A for bZIP60 mRNA splicing and downstream canonical UPR gene expression is dependent on N780 in the RNase domain and D570/K572 in the ATP-binding pocket of IRE1A. In contrast, the auto-phosphorylation activity of IRE1A is dependent on D570/K572 and D590 of IRE1A, which is important for non-canonical UPR gene expression and the shoot growth retardation phenotype.