Department of Biochemistry, School of Biotechnology and Graduate School of Biochemistry at Yeungnam University, Gyeongsan, South Korea.
Apoptosis. 2010 Dec;15(12):1444-52. doi: 10.1007/s10495-010-0544-2.
Caspase-2 is critical for genotoxic stress induced apoptosis and is activated by formation of the PIDDosome, an oligomeric caspase-2 activating complex. The PIDDosome comprises three protein components, PIDD, RAIDD, and caspase-2. RAIDD contains both a death domain (DD) and a caspase recruitment domain (CARD). It acts as the bridge to recruit PIDD using the DD: DD interaction and to recruit caspase-2 via the CARD: CARD interaction. Here we report biochemical characterization and in vitro reconstitution of the core interactions in the PIDDosome. We show that RAIDD CARD and RAIDD DD interact with their binding partners, caspase-2 CARD and PIDD DD, respectively. However, full-length RAIDD fails to interact with either caspase-2 CARD or PIDD DD under a physiological buffer condition. We reveal that this lack of interaction of full-length RAIDD is not due to its tendency to aggregate under the physiological buffer condition, as decreasing full-length RAIDD aggregation using high salt or high pH is not able to promote complex formation. Instead, full-length RAIDD forms both binary and ternary complexes under a low salt condition. Successful in vitro reconstitution of the ternary complex provides a basis for further structural studies of the PIDDosome.
半胱天冬酶-2（Caspase-2）对于由遗传毒性应激诱导的细胞凋亡至关重要，其可被 PIDDosome 激活，后者是一种寡聚半胱天冬酶-2 激活复合物。PIDDosome 由三个蛋白成分组成：PIDD、RAIDD 和 caspase-2。RAIDD 含有死亡结构域（DD）和半胱氨酸蛋白酶募集结构域（CARD）。它充当桥梁，通过 DD：DD 相互作用利用 DD 招募 PIDD，通过 CARD：CARD 相互作用利用 CARD 招募 caspase-2。在此，我们报道了 PIDDosome 中核心相互作用的生化特征和体外重建。我们表明，RAIDD CARD 和 RAIDD DD 分别与它们的结合伴侣 caspase-2 CARD 和 PIDD DD 相互作用。然而，在生理缓冲条件下，全长 RAIDD 不能与 caspase-2 CARD 或 PIDD DD 相互作用。我们揭示，全长 RAIDD 的这种缺乏相互作用不是由于其在生理缓冲条件下倾向于聚集，因为使用高盐或高 pH 值降低全长 RAIDD 聚集不能促进复合物形成。相反，全长 RAIDD 在低盐条件下形成二聚体和三聚体复合物。成功的体外重建三元复合物为 PIDDosome 的进一步结构研究提供了基础。
