A designed redox-controlled caspase

作者：Witkowski Witold A; Hardy Jeanne A^*

来源：Protein Science, 2011, 20(8): 1421-1431.

DOI：10.1002/pro.673

• apoptosis
• caspase activation
• loop conformation
• disulfide
• engineered cysteine
• induced cell death
• allostery

Caspases are a powerful class of cysteine proteases. Introduction of activated caspases in healthy or cancerous cells results in induction of apoptotic cell death. In this study, we have designed and characterized a version of caspase-7 that can be inactivated under oxidizing extracellular conditions and then reactivated under reducing intracellular conditions. This version of caspase-7 is allosterically inactivated when two of the substrate-binding loops are locked together via an engineered disulfide. When this disulfide is reduced, the protein regains its full function. The inactive loop-locked version of caspase-7 can be readily observed by immunoblotting and mass spectrometry. The reduced and reactivated form of the enzyme observed crystallographically is the first caspase-7 structure in which the substrate-binding groove is properly ordered even in the absence of an active-site ligand. In the reactivated structure, the catalytic-dyad cysteine-histidine are positioned 3.5 angstrom apart in an orientation that is capable of supporting catalysis. This redox-controlled version of caspase-7 is particularly well suited for targeted cell death in concert with redox-triggered delivery vehicles.

• 出版日期2011-8