A constitutively active and uninhibitable caspase-3 zymogen efficiently induces apoptosis.
A constitutively active and uninhibitable caspase-3 zymogen efficiently induces apoptosis.
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DOI：
10.1042/bj20090825
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发表时间：
2009-12-10
期刊：
影响因子：
--
通讯作者：
Clark AC
中科院分区：
文献类型：
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作者：
Walters J;Pop C;Scott FL;Drag M;Swartz P;Mattos C;Salvesen GS;Clark AC
半胱天冬酶-3酶原具有基本上为零的活性，直到其在细胞凋亡期间被引发剂半胱天冬酶切割。然而，二聚体界面中的V266 E突变在不存在链切割的情况下激活蛋白酶。我们发现，低浓度的假激活的半胱氨酸天冬氨酸蛋白酶原-3迅速杀死哺乳动物细胞，重要的是，这种蛋白质不被切割，也不是有效地抑制内源性调节XIAP（X连锁的细胞凋亡抑制剂）。该变体的1.63 nm（1 nm = 0.1 nm）结构表明，该突变被容纳在二聚体界面处，以产生具有与野生型胱天蛋白酶-3基本上相同的活性和特异性的酶。结构建模预测，界面突变防止亚基间接头在二聚体界面中结合，从而允许活性位点在不存在切割的情况下在半胱天冬酶原中形成。通过构象转换而不是通过链切割直接激活半胱天冬酶原-3可能导致诱导细胞死亡的新的治疗策略。
The caspase-3 zymogen has essentially zero activity until it is cleaved by initiator caspases during apoptosis. However, a mutation of V266E in the dimer interface activates the protease in the absence of chain cleavage. We show that low concentrations of the pseudo-activated procaspase-3 kill mammalian cells rapidly and, importantly, this protein is not cleaved nor is it inhibited efficiently by the endogenous regulator XIAP (X-linked inhibitor of apoptosis). The 1.63 Å (1 Å = 0.1 nm) structure of the variant demonstrates that the mutation is accommodated at the dimer interface to generate an enzyme with substantially the same activity and specificity as wild-type caspase-3. Structural modelling predicts that the interface mutation prevents the intersubunit linker from binding in the dimer interface, allowing the active sites to form in the procaspase in the absence of cleavage. The direct activation of procaspase-3 through a conformational switch rather than by chain cleavage may lead to novel therapeutic strategies for inducing cell death.