Dimerization mechanisms of two procaspase subfamilies

描述（由申请人提供）：导致原aspase激活的机制在细胞凋亡和炎症的调节中发挥核心作用。对于所有原葡聚糖酶，二聚体的形成是加工过程中的关键事件，因为酶的活性位点由二聚体的两个单体组成的环组成。然而，caspase亚家族在二聚化和成熟方面存在根本差异，这种差异是调节细胞凋亡的关键方面。一些炎症和引发原葡聚糖酶作为无活性单体存在于细胞中，但这些蛋白在二聚化时具有相对较高的酶活性。对于这些半胱天酶，链切割只是稳定了活性位点。相比之下，刽子手procaspase-3是一个稳定的二聚体，但它的酶活性非常低。在这种情况下，成熟依赖于起始原葡聚糖酶的裂解。我们的长期目标是了解原葡聚糖酶的二聚化、活化和酶活性是如何耦合的。总的来说，我们想要确定为什么procaspase-1是一个单体，但活性位点在二聚化时形成正确。相反，我们想确定为什么稳定的procaspase-3二聚体不活跃。我们假设procaspase二聚体以两种主要构象存在，其中只有一种是活性的，并且在procaspase-3的情况下，非活性形式是最稳定的。此外，我们认为二聚体界面上的变构位点影响两种形式之间的构象转换，并将二聚化与活性位点的形成结合起来。我们已经表明，蛋白质的三个区域可能是重要的影响寡聚状态和稳定失活形式的原葡聚糖酶。我们建议使用生化和生物物理分析、蛋白质折叠研究和x射线晶体学研究来检查蛋白质的这三个区域。原aspase的激活机制在生物学上是重要的，因为它们允许在细胞死亡中严格调节半胱天冬酶的活性，从维持启动原aspase的单体状态到稳定二聚体效应原aspase的失活形式。了解半胱天冬酶的激活过程为开发干预其在细胞中的活性的策略提供了关键。公共卫生相关性：了解半胱天冬酶二聚体和激活有可能影响许多自身免疫性疾病、心脏病和癌症的治疗策略。学习有选择地控制细胞凋亡水平是治疗的重要一步，因为细胞凋亡失调是这些疾病的共同因素。

DESCRIPTION (provided by applicant): The mechanisms that lead to the activation of procaspases play central roles in the regulation of apoptosis and inflammation. For all procaspases, formation of a dimer is a critical event in processing because the active sites of the enzyme are comprised of loops contributed by both monomers of the dimer. However, a fundamental difference exists in the caspase subfamilies regarding dimerization and maturation, and this difference is a key aspect for regulating apoptosis. Several inflammatory and initiator procaspases exist as inactive monomers in the cell, but the proteins have relatively high enzymatic activity upon dimerization. For those caspases, chain cleavage simply stabilizes the active site. In contrast, the executioner procaspase-3 is a stable dimer, but it has very little enzymatic activity. In this case, maturation is dependent on cleavage by the initiator procaspases. Our long-term goals are to understand how dimerization, activation and enzymatic activity are coupled for procaspases. Overall, we want to determine why procaspase-1 is a monomer, but yet the active sites form properly upon dimerization. In contrast, we want to determine why the stable dimer of procaspase-3 is not active. We hypothesize that the procaspase dimer exists in two primary conformations, only one of which is active, and that the inactive form is most stable in the case of procaspase-3. Furthermore, we suggest that an allosteric site in the dimer interface affects the conformational switch between the two forms and couples dimerization to active site formation. We have shown that three regions of the protein may be important in affecting the oligomeric state and in stabilizing the inactive form of the procaspase. We propose to use biochemical and biophysical assays, protein folding studies, and X-ray crystallographic studies to examine these three regions of the protein. The procaspase activation mechanisms are important biologically because they allow for the tight regulation of caspase activity in cell death, from maintaining the monomeric state of initiator procaspases to stabilizing the inactive form of dimeric effector procaspases. Understanding the caspase activation process provides a key t develop strategies to intervene in their activities in the cell. PUBLIC HEALTH RELEVANCE: Understanding caspase dimerization and activation has the potential to affect therapeutic strategies for a number of autoimmune diseases, heart disease, and cancers. Learning to selectively manipulate the level of apoptosis is an important step in treatment because the dysregulation of apoptosis is a common factor to these diseases.