Program in Apoptosis and Cell Death Research, Sanford-BurnhamMedical Research Institute, 10901 North Torrey Pines Road, La Jolla, California 92037, USA.
Biochemistry. 2010 Sep 28;49(38):8307-15. doi: 10.1021/bi100968m.
Two apical caspases, caspase-8 and -10, are involved in the extrinsic death receptor pathway in humans, but it is mainly caspase-8 in its apoptotic and nonapoptotic functions that has been an intense research focus. In this study we concentrate on caspase-10, its mechanism of activation, and the role of the intersubunit cleavage. Our data obtained through in vitro dimerization assays strongly suggest that caspase-10 follows the proximity-induced dimerization model for apical caspases. Furthermore, we compare the specificity and activity of the wild-type protease with a mutant incapable of autoprocessing by using positional scanning substrate analysis and cleavage of natural protein substrates. These experiments reveal a striking difference between the wild type and the mutant, leading us to hypothesize that the single chain enzyme has restricted activity on most proteins but high activity on the proapoptotic protein Bid, potentially supporting a prodeath role for both cleaved and uncleaved caspase-10.
两种顶端半胱氨酸天冬氨酸蛋白酶（caspase），即 caspase-8 和 -10，参与了人类的外在死亡受体途径，但在凋亡和非凋亡功能方面，主要是 caspase-8 一直是研究的重点。在这项研究中，我们集中研究 caspase-10、其激活机制以及亚基切割的作用。我们通过体外二聚化测定获得的数据强烈表明，caspase-10 遵循顶端半胱氨酸天冬氨酸蛋白酶的临近诱导二聚化模型。此外，我们使用位置扫描底物分析和天然蛋白底物的切割比较了野生型蛋白酶和不能自我加工的突变体的特异性和活性。这些实验揭示了野生型和突变体之间的显著差异，使我们假设单链酶对大多数蛋白质的活性有限，但对促凋亡蛋白 Bid 的活性很高，这可能支持切割和未切割的 caspase-10 都具有促死亡作用。
