Gavathiotis Evripidis, Suzuki Motoshi, Davis Marguerite L, Pitter Kenneth, Bird Gregory H, Katz Samuel G, Tu Ho-Chou, Kim Hyungjin, Cheng Emily H-Y, Tjandra Nico, Walensky Loren D
Department of Pediatric Oncology and the Program in Cancer Chemical Biology, Dana-Farber Cancer Institute, 44 Binney Street, Boston, Massachusetts 02115, USA.
Nature. 2008 Oct 23;455(7216):1076-81. doi: 10.1038/nature07396.
BAX is a pro-apoptotic protein of the BCL-2 family that is stationed in the cytosol until activated by a diversity of stress stimuli to induce cell death. Anti-apoptotic proteins such as BCL-2 counteract BAX-mediated cell death. Although an interaction site that confers survival functionality has been defined for anti-apoptotic proteins, an activation site has not been identified for BAX, rendering its explicit trigger mechanism unknown. We previously developed stabilized alpha-helix of BCL-2 domains (SAHBs) that directly initiate BAX-mediated mitochondrial apoptosis. Here we demonstrate by NMR analysis that BIM SAHB binds BAX at an interaction site that is distinct from the canonical binding groove characterized for anti-apoptotic proteins. The specificity of the human BIM-SAHB-BAX interaction is highlighted by point mutagenesis that disrupts functional activity, confirming that BAX activation is initiated at this novel structural location. Thus, we have now defined a BAX interaction site for direct activation, establishing a new target for therapeutic modulation of apoptosis.
BAX是BCL-2家族中的一种促凋亡蛋白，它驻留在细胞质中，直到被多种应激刺激激活以诱导细胞死亡。抗凋亡蛋白如BCL-2可对抗BAX介导的细胞死亡。尽管已经为抗凋亡蛋白定义了赋予生存功能的相互作用位点，但尚未确定BAX的激活位点，其明确的触发机制尚不清楚。我们之前开发了BCL-2结构域稳定化α-螺旋（SAHBs），它可直接启动BAX介导的线粒体凋亡。在这里，我们通过核磁共振分析证明，BIM SAHB在一个与抗凋亡蛋白特有的典型结合凹槽不同的相互作用位点结合BAX。点突变破坏功能活性突出了人BIM-SAHB-BAX相互作用的特异性，证实BAX激活在此新的结构位置启动。因此，我们现在定义了一个用于直接激活的BAX相互作用位点，为凋亡的治疗性调节建立了一个新靶点。
