The Functional Differences between Pro-survival and Pro-apoptotic B Cell Lymphoma 2 (Bcl-2) Proteins Depend on Structural Differences in Their Bcl-2 Homology 3 (BH3) Domains
The Functional Differences between Pro-survival and Pro-apoptotic B Cell Lymphoma 2 (Bcl-2) Proteins Depend on Structural Differences in Their Bcl-2 Homology 3 (BH3) Domains
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DOI：
10.1074/jbc.m114.610758
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发表时间：
2014-12-26
影响因子：
4.8
通讯作者：
Fairlie, W. Douglas
中科院分区：
文献类型：
--
作者：
Lee, Erinna F.;Dewson, Grant;Fairlie, W. Douglas
BCL-2同源3(BH3)结构域是一类短序列基序，在固有的细胞死亡途径中介导了B细胞淋巴瘤2(BCL-2)家族蛋白之间的几乎所有蛋白质-蛋白质相互作用。尽管这些序列的主要功能被认为与诱导细胞死亡有关，但在存续成员和促凋亡成员上都发现了这些序列。在这里，我们确定了生存蛋白BH3结构域的关键特征，这些特征在功能上将它们与促凋亡蛋白区分开来。生化和X射线结晶学研究表明，这些差异降低了大多数支持生存的蛋白质形成高亲和力的“BH3-in-Grove”复合体的能力，这种复合体对诱导细胞死亡至关重要。将这些残基转换为Bcl-2同源拮抗剂/杀手(Bak)中的相应残基可以增加分离的BH3结构域与促生存蛋白的结合亲和力；然而，由于蛋白质不稳定，它们在亲本蛋白背景下的交换会导致蛋白酶体的快速降解。这得到了进一步的X射线结晶学研究的支持，这些研究捕捉到了一种有利于生存的蛋白质Bclw中这种不稳定的元素。在促凋亡的Bak中，我们证明了相应的识别残基对于其杀伤细胞的能力和生存蛋白的拮抗作用是重要的。
Bcl-2 homology 3 (BH3) domains are short sequence motifs that mediate nearly all protein-protein interactions between B cell lymphoma 2 (Bcl-2) family proteins in the intrinsic apoptotic cell death pathway. These sequences are found on both prosurvival and pro-apoptotic members, although their primary function is believed to be associated with induction of cell death. Here, we identify critical features of the BH3 domains of prosurvival proteins that distinguish them functionally from their pro-apoptotic counterparts. Biochemical and x-ray crystallographic studies demonstrate that these differences reduce the capacity of most pro-survival proteins to form high affinity "BH3-in-groove" complexes that are critical for cell death induction. Switching these residues for the corresponding residues in Bcl-2 homologous antagonist/killer (Bak) increases the binding affinity of isolated BH3 domains for pro-survival proteins; however, their exchange in the context of the parental protein causes rapid proteasomal degradation due to protein destabilization. This is supported by further x-ray crystallographic studies that capture elements of this destabilization in one pro-survival protein, Bcl-w. In pro-apoptotic Bak, we demonstrate that the corresponding distinguishing residues are important for its cell-killing capacity and antagonism by prosurvival proteins.