BINDING PROTEIN Is a Master Regulator of the Endoplasmic Reticulum Stress Sensor/Transducer bZIP28 in Arabidopsis[C][W][OA]
BINDING PROTEIN Is a Master Regulator of the Endoplasmic Reticulum Stress Sensor/Transducer bZIP28 in Arabidopsis[C][W][OA]
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DOI：
10.1105/tpc.113.110684
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发表时间：
2013-04
期刊：
影响因子：
11.6
通讯作者：
R. Srivastava;Yan Deng;Shweta Shah;A. Rao;S. Howell
中科院分区：
文献类型：
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作者：
R. Srivastava;Yan Deng;Shweta Shah;A. Rao;S. Howell
本工作研究了Bip在非胁迫条件下在内质网中保留bZIP28的作用，揭示了拟南芥中的bip是UPR信号通路的主要调节者，通过与bZIP28 C末端尾部的内在无序区域结合来响应胁迫和功能。结合蛋白(Bip)是内质网(ER)管腔中的一种主要伴侣蛋白，本研究表明Bip与应力传感器/转导蛋白bZIP28的C端末端结合，bZIP28是一种膜相关转录因子，在非应激条件下将其保留在内质网中。作为对内质网应激的反应，Bip与bZIP28解离，使其能够从内质网被动员到高尔基体，在那里它被蛋白质降解处理并释放进入细胞核。在非应激条件下，Bip通过其底物结合域与bZIP28结合，就像它与其他客户蛋白结合一样。即使当bZIP28的S退出ER或其从高尔基体释放被阻止时，BIP也与bZIP28解离。BiP1和BiP3都与bZIP28结合，在应激条件下，BiP的过表达将bZIP28滞留在内质网中。BZIP28的C末端截短突变体消除了大部分管腔结构域，不与Bip结合，在非应激条件下不保留在内质网中。在噬菌体展示系统中鉴定了bZIP28 C-末端的BiP结合位点。发现BiP与bZIP28的S腔向尾巴上固有的无序区域结合。因此，Bip从bZIP28的C-末端解离是激活植物中未折叠蛋白反应信号通路的一条臂的主要开关。
This work examines the role of BiP in retaining bZIP28 in the ER under unstressed conditions, revealing that the BiPs in Arabidopsis are master regulators of the UPR signaling pathway in response to stress and function by binding to the intrinsically disordered regions of the C-terminal tail of bZIP28. BINDING PROTEIN (BiP) is a major chaperone in the endoplasmic reticulum (ER) lumen, and this study shows that BiP binds to the C-terminal tail of the stress sensor/transducer bZIP28, a membrane-associated transcription factor, retaining it in the ER under unstressed conditions. In response to ER stress, BiP dissociates from bZIP28, allowing it to be mobilized from the ER to the Golgi where it is proteolytically processed and released to enter the nucleus. Under unstressed conditions, BiP binds to bZIP28 as it binds to other client proteins, through its substrate binding domain. BiP dissociates from bZIP28 even when bZIP28’s exit from the ER or its release from the Golgi is blocked. Both BiP1 and BiP3 bind bZIP28, and overexpression of either BiP detains bZIP28 in the ER under stress conditions. A C-terminally truncated mutant of bZIP28 eliminating most of the lumenal domain does not bind BiP and is not retained in the ER under unstressed conditions. BiP binding sites in the C-terminal tail of bZIP28 were identified in a phage display system. BiP was found to bind to intrinsically disordered regions on bZIP28’s lumen-facing tail. Thus, the dissociation of BiP from the C-terminal tail of bZIP28 is a major switch that activates one arm of the unfolded protein response signaling pathway in plants.