| Structural highlights
Function
CED4_CAEEL Isoform a plays a major role in programmed cell death (PCD, apoptosis). Egl-1 binds to and directly inhibits the activity of ced-9, releasing the cell death activator ced-4 from a ced-9/ced-4 containing protein complex and allowing ced-4 to activate the cell-killing caspase ced-3. Isoform b prevents PCD.[1] [2] [3] [4] [5]
Publication Abstract from PubMed
Programmed cell death in Caenorhabditis elegans requires activation of the caspase CED-3, which strictly depends on CED-4. CED-4 forms an octameric apoptosome, which binds the CED-3 zymogen and facilitates its autocatalytic maturation. Despite recent advances, major questions remain unanswered. Importantly, how CED-4 recognizes CED-3 and how such binding facilitates CED-3 activation remain completely unknown. Here we demonstrate that the L2' loop of CED-3 directly binds CED-4 and plays a major role in the formation of an active CED-4-CED-3 holoenzyme. The crystal structure of the CED-4 apoptosome bound to the L2' loop fragment of CED-3, determined at 3.2 A resolution, reveals specific interactions between a stretch of five hydrophobic amino acids from CED-3 and a shallow surface pocket within the hutch of the funnel-shaped CED-4 apoptosome. Structure-guided biochemical analysis confirms the functional importance of the observed CED-4-CED-3 interface. Structural analysis together with published evidence strongly suggest a working model in which two molecules of CED-3 zymogen, through specific recognition, are forced into the hutch of the CED-4 apoptosome, consequently undergoing dimerization and autocatalytic maturation. The mechanism of CED-3 activation represents a major revision of the prevailing model for initiator caspase activation.
Mechanistic insights into CED-4-mediated activation of CED-3.,Huang W, Jiang T, Choi W, Qi S, Pang Y, Hu Q, Xu Y, Gong X, Jeffrey PD, Wang J, Shi Y Genes Dev. 2013 Sep 15;27(18):2039-48. doi: 10.1101/gad.224428.113. PMID:24065769[6]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Yuan J, Horvitz HR. The Caenorhabditis elegans cell death gene ced-4 encodes a novel protein and is expressed during the period of extensive programmed cell death. Development. 1992 Oct;116(2):309-20. PMID:1286611
- ↑ Shaham S, Horvitz HR. An alternatively spliced C. elegans ced-4 RNA encodes a novel cell death inhibitor. Cell. 1996 Jul 26;86(2):201-8. PMID:8706125
- ↑ Wu D, Wallen HD, Nunez G. Interaction and regulation of subcellular localization of CED-4 by CED-9. Science. 1997 Feb 21;275(5303):1126-9. PMID:9027313
- ↑ Chen F, Hersh BM, Conradt B, Zhou Z, Riemer D, Gruenbaum Y, Horvitz HR. Translocation of C. elegans CED-4 to nuclear membranes during programmed cell death. Science. 2000 Feb 25;287(5457):1485-9. PMID:10688797
- ↑ Yan N, Gu L, Kokel D, Chai J, Li W, Han A, Chen L, Xue D, Shi Y. Structural, biochemical, and functional analyses of CED-9 recognition by the proapoptotic proteins EGL-1 and CED-4. Mol Cell. 2004 Sep 24;15(6):999-1006. PMID:15383288 doi:10.1016/j.molcel.2004.08.022
- ↑ Huang W, Jiang T, Choi W, Qi S, Pang Y, Hu Q, Xu Y, Gong X, Jeffrey PD, Wang J, Shi Y. Mechanistic insights into CED-4-mediated activation of CED-3. Genes Dev. 2013 Sep 15;27(18):2039-48. doi: 10.1101/gad.224428.113. PMID:24065769 doi:http://dx.doi.org/10.1101/gad.224428.113
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