The membrane-associated transcription factor, bZlP28, is relocated from the endoplasmic reticulum （ER） to the Golgi and proteolytically released from the membrane mediated by two proteases, SlP and S2P, in response ...The membrane-associated transcription factor, bZlP28, is relocated from the endoplasmic reticulum （ER） to the Golgi and proteolytically released from the membrane mediated by two proteases, SlP and S2P, in response to ER stress in Arabidopsis. The activated N-terminal domain recruits nuclear factor Y （NF-Y） subunits in the nucleus to regulate ER stress downstream genes. Little is known about the functions of the bZIP28 C-terminal lumen-facing domain. Here, we provide novel insights into how the ER lumen-facing domain affects the biological function and organelle-to-organelle movement of bZIP28 in the ER stress response. First, we demonstrated the functional redundancy of bZlP28 and bZIP60 by generation and analysis of the bZIP28 and bZIP60 double mutant zip28zip60. Subsequent genetic complementation experiments in zip28zip60 background with deletions on bZlP28 lumen-facing domain highlighted the importance of lumen-facing domain for its in vivo function of bZIP28 in the ER stress response. The protein subcellular localization and Western blotting results further revealed that the bZIP28 lumen-facing domain contains ER retention signal which is important for the proteolytic activation of bZIP28. Thus, the bZIP28 lumen-facing C-terminus plays important roles in the ER-to-Golgi movement of bZlP28, which may contribute to the sensing of the ER stress.展开更多
基金This study was financially supported by grants from the National Basic Research Program of China （973 Program, 2012CB910500）, the National Natural Science Foundation of China （#31171157 #31070233 #31222008）, and the Shanghai Pujiang Talent Program （11PJ1400700）. No conflict of interest declared.
文摘The membrane-associated transcription factor, bZlP28, is relocated from the endoplasmic reticulum （ER） to the Golgi and proteolytically released from the membrane mediated by two proteases, SlP and S2P, in response to ER stress in Arabidopsis. The activated N-terminal domain recruits nuclear factor Y （NF-Y） subunits in the nucleus to regulate ER stress downstream genes. Little is known about the functions of the bZIP28 C-terminal lumen-facing domain. Here, we provide novel insights into how the ER lumen-facing domain affects the biological function and organelle-to-organelle movement of bZIP28 in the ER stress response. First, we demonstrated the functional redundancy of bZlP28 and bZIP60 by generation and analysis of the bZIP28 and bZIP60 double mutant zip28zip60. Subsequent genetic complementation experiments in zip28zip60 background with deletions on bZlP28 lumen-facing domain highlighted the importance of lumen-facing domain for its in vivo function of bZIP28 in the ER stress response. The protein subcellular localization and Western blotting results further revealed that the bZIP28 lumen-facing domain contains ER retention signal which is important for the proteolytic activation of bZIP28. Thus, the bZIP28 lumen-facing C-terminus plays important roles in the ER-to-Golgi movement of bZlP28, which may contribute to the sensing of the ER stress.
