Department of Physiology and Biophysics, Boston University School of Medicine, 700 Albany Street, Boston, MA 02118, USA.
Structure. 2011 Jan 12;19(1):128-40. doi: 10.1016/j.str.2010.10.009.
The Drosophila Apaf-1 related killer forms an apoptosome in the intrinsic cell death pathway. In this study we show that Dark forms a single ring when initiator procaspases are bound. This Dark-Dronc complex cleaves DrICE efficiently; hence, a single ring represents the Drosophila apoptosome. We then determined the 3D structure of a double ring at ∼6.9 Å resolution and created a model of the apoptosome. Subunit interactions in the Dark complex are similar to those in Apaf-1 and CED-4 apoptosomes, but there are significant differences. In particular, Dark has "lost" a loop in the nucleotide-binding pocket, which opens a path for possible dATP exchange in the apoptosome. In addition, caspase recruitment domains (CARDs) form a crown on the central hub of the Dark apoptosome. This CARD geometry suggests that conformational changes will be required to form active Dark-Dronc complexes. When taken together, these data provide insights into apoptosome structure, function, and evolution.
果蝇 Apaf-1 相关的杀手在内在细胞死亡途径中形成凋亡体。在这项研究中，我们表明 Dark 在起始半胱天冬酶结合时形成单个环。这种 Dark-Dronc 复合物有效地切割 DrICE；因此，单个环代表果蝇凋亡体。然后，我们确定了一个约 6.9Å 分辨率的双链环的 3D 结构，并创建了凋亡体模型。Dark 复合物中的亚基相互作用与 Apaf-1 和 CED-4 凋亡体相似，但存在显著差异。特别是，Dark 在核苷酸结合口袋中“丢失”了一个环，这为凋亡体中可能的 dATP 交换开辟了一条途径。此外，半胱氨酸天冬氨酸蛋白酶募集结构域 (CARD) 在 Dark 凋亡体的中央枢纽上形成一个冠。这种 CARD 几何形状表明，形成活性 Dark-Dronc 复合物需要构象变化。综合来看，这些数据为凋亡体结构、功能和进化提供了深入的了解。
