Engineering a dimeric caspase-9: a re-evaluation of the induced proximity model for caspase activation.
Engineering a dimeric caspase-9: a re-evaluation of the induced proximity model for caspase activation.
复制标题
工程二聚体caspase-9：重新评估caspase激活的诱导接近模型。
DOI：
10.1371/journal.pbio.0030183
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发表时间：
2005-06
期刊：
影响因子：
9.8
通讯作者：
Shi, YG
中科院分区：
文献类型：
--
作者：
Chao, Y;Shiozaki, EN;Srinivasula, SM;Rigotti, DJ;Fairman, R;Shi, YG
半胱天冬酶负责执行程序性细胞死亡（凋亡），必须经过蛋白水解激活，以响应凋亡刺激，才能发挥作用。引发剂caspase激活的机制已被诱导接近模型推广，该模型被认为驱动二聚化介导的caspase激活。引发剂caspase caspase-9主要以单体形式存在于溶液中。为了检验诱导接近模型，我们设计了一个本构二聚体caspase-9，通过消除二聚体界面的空间位阻。工程caspase-9的晶体结构与野生型caspase-9非常相似，包括所有相关的结构细节和两个单体的不对称性质。与WT caspase-9相比，该工程二聚体在体外表现出更高水平的催化活性，表达时诱导更有效的细胞死亡。然而，二聚体caspase-9的催化活性仅为apaf -1活化caspase-9的一小部分。此外，与WT caspase-9相比，二聚体caspase-9的活性不再以apaf -1依赖的方式显着增强。这些发现表明，caspase-9的二聚化可能与Apaf-1激活的caspase-9有质的不同，并结合其他证据，假设了caspase激活的诱导构象模型。来自工程caspase-9二聚体的证据表明，与普遍的假设相反，二聚化可能不是caspase-9激活的关键步骤。
Caspases are responsible for the execution of programmed cell death (apoptosis) and must undergo proteolytic activation, in response to apoptotic stimuli, to function. The mechanism of initiator caspase activation has been generalized by the induced proximity model, which is thought to drive dimerization-mediated activation of caspases. The initiator caspase, caspase-9, exists predominantly as a monomer in solution. To examine the induced proximity model, we engineered a constitutively dimeric caspase-9 by relieving steric hindrance at the dimer interface. Crystal structure of the engineered caspase-9 closely resembles that of the wild-type (WT) caspase-9, including all relevant structural details and the asymmetric nature of two monomers. Compared to the WT caspase-9, this engineered dimer exhibits a higher level of catalytic activity in vitro and induces more efficient cell death when expressed. However, the catalytic activity of the dimeric caspase-9 is only a small fraction of that for the Apaf-1-activated caspase-9. Furthermore, in contrast to the WT caspase-9, the activity of the dimeric caspase-9 can no longer be significantly enhanced in an Apaf-1-dependent manner. These findings suggest that dimerization of caspase-9 may be qualitatively different from its activation by Apaf-1, and in conjunction with other evidence, posit an induced conformation model for the activation of initiator caspases. Evidence from an engineered caspase-9 dimer suggests that, contrary to the prevailing hypothesis, dimerization may not be the critical step in caspase-9 activation.
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DOI：
10.1107/s0907444998003254
发表时间：
1998-09-01
期刊：
ACTA CRYSTALLOGRAPHICA SECTION D-BIOLOGICAL CRYSTALLOGRAPHY
影响因子：
--
作者：
Brunger, AT;Adams, PD;Warren, GL
通讯作者：
Warren, GL
DOI：
10.1073/pnas.231465798
发表时间：
2001-12-04
影响因子：
11.1
作者：
Renatus, M;Stennicke, HR;Salvesen, GS
通讯作者：
Salvesen, GS
DOI：
10.1073/pnas.221580098
发表时间：
2001-12-18
影响因子：
11.1
作者：
Riedl, SJ;Fuentes-Prior, P;Bode, W
通讯作者：
Bode, W
影响因子：
64.8
作者：
Srinivasula, SM;Hegde, R;Alnemri, ES
通讯作者：
Alnemri, ES
影响因子：
16
作者：
Donepudi, M;Mac Sweeney, A;Grütter, MG
通讯作者：
Grütter, MG