earticle

영어

Endoplasmic reticulum (ER) stress induced by various stimuli leads to accumulation of unfolded proteins and unfolded protein response (UPR) in plants. P58IPK induced by ER stress is known to inhibit the activity of protein kinase RNA-like ER kinase (PERK) in mammalian cells. Both genetic reduction of PERK expression and pharmacological inhibition of its activity reduces p-eIF2α levels resulting in a reduction in general protein translation in mammalian cells. However, it has been unclear whether a similar mechanism is applicable to the P58IPK in plants. To investigate physiological function and molecular mechanism of the P58IPK in plants, a loss-of-function mutant of P58IPK(p58ipk) and P58IPKoverexpressingplants(CVMVp:P58IPK) have been analysed. We found that p58ipk is more resistant to tunicamycin (TM), an inhibitor of protein N-glycosylation, than the Arabidopsis Columbia-0 (Col-0) ecotype background and CVMVp:P58IPK. Gene expression profiling studies indicate that transcript levels of ER stress marker genes are more higher in p58ipk than those in Col-0 and CVMVp:P58IPK. However, unlike its mammalian counterpart, P58IPK in Arabidopsis do not affect p-eIF2α levels but interacts with ribosome to inhibit protein synthesis. These results indicate that P58IPK is also implicated in UPR in plants but different molecular mechanism accounts for physiological effects of the loss-of-function mutation of P58IPKin plants.