Caspase-9 holoenzyme is a specific and optimal procaspase-3 processing machine Journal Article
| Authors: | Yin, Q.; Park, H. H.; Chung, J. Y.; Lin, S. C.; Lo, Y. C.; da Graca, L. S.; Jiang, X.; Wu, H. |
| Article Title: | Caspase-9 holoenzyme is a specific and optimal procaspase-3 processing machine |
| Abstract: | Caspase-9 activation is critical for intrinsic cell death. The activity of caspase-9 is increased dramatically upon association with the apoptosome, and the apoptosome bound caspase-9 is the caspase-9 holoenzyme (C9Holo). In this study, we use quantitative enzymatic assays to fully characterize C9Holo and a leucine-zipper-linked dimeric caspase-9 (LZ-C9). We surprisingly show that LZ-C9 is more active than C9Holo for the optimal caspase-9 peptide substrate LEHD-AFC but is much less active than C9Holo for the physiological substrate procaspase-3. The measured K m values of C9Holo and LZ-C9 for LEHD-AFC are similar, demonstrating that dimerization is sufficient for catalytic activation of caspase-9. The lower activity of C9Holo against LEHD-AFC may be attributed to incomplete C9Holo assembly. However, the measured K m of C9Holo for procaspase-3 is much lower than that of LZ-C9. Therefore, in addition to dimerization, the apoptosome activates caspase-9 by enhancing its affinity for procaspase-3, which is important for procaspase-3 activation at the physiological concentration. © 2006 Elsevier Inc. All rights reserved. |
| Keywords: | animals; apoptosis; models, biological; caspase 3; enzyme activation; enzyme activity; enzyme substrate; caspases; blotting, western; kinetics; enzyme analysis; quantitative analysis; escherichia coli; substrate specificity; spodoptera; models, molecular; dimerization; protein structure, tertiary; caspase 9; catalysis; leucine; enzyme specificity; catalytic domain; enzyme assay; histidine; chromatography, gel; electrophoresis, polyacrylamide gel; fluorescent antibody technique, indirect; enzyme active site; scattering, radiation; light; chromatography, affinity; michaelis menten kinetics; holoenzyme; baculoviridae; procaspase 9; holoenzymes |
| Journal Title: | Molecular Cell |
| Volume: | 22 |
| Issue: | 2 |
| ISSN: | 1097-2765 |
| Publisher: | Cell Press |
| Date Published: | 2006-04-21 |
| Start Page: | 259 |
| End Page: | 268 |
| Language: | English |
| DOI: | 10.1016/j.molcel.2006.03.030 |
| PUBMED: | 16630893 |
| PROVIDER: | scopus |
| PMCID: | PMC2904439 |
| DOI/URL: | |
| Notes: | --- - "Cited By (since 1996): 31" - "Export Date: 4 June 2012" - "CODEN: MOCEF" - "Source: Scopus" |
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