title: Structural, biochemical, and functional analyses of CED-9 recognition by the proapoptotic proteins EGL-1 and CED-4.
abstract: Programmed cell death in Caenorhabditis elegans is initiated by the binding of EGL-1 to CED-9, which disrupts the CED-4/CED-9 complex and allows CED-4 to activate the cell-killing caspase CED-3. Here we demonstrate that the C-terminal half of EGL-1 is necessary and sufficient for binding to CED-9 and for killing cells. Structure of the EGL-1/CED-9 complex revealed that EGL-1 adopts an extended alpha-helical conformation and induces substantial structural rearrangements in CED-9 upon binding. EGL-1 interface mutants failed to bind to CED-9 or to release CED-4 from the CED-4/CED-9 complex, and were unable to induce cell death in vivo. A surface patch on CED-9, different from that required for binding to EGL-1, was identified to be responsible for binding to CED-4. These data suggest a working mechanism for the release of CED-4 from the CED-4/CED-9 complex upon EGL-1 binding and provide a mechanistic framework for understanding apoptosis activation in C. elegans.
authors.affiliation: Department of Molecular Biology, Princeton University, Lewis Thomas Laboratory, Washington Road, Princeton, NJ 08544, USA.
authors.forename: Nieng
authors.initials: N
authors.lastname: Yan
authors.forename: Lichuan
authors.initials: L
authors.lastname: Gu
authors.forename: David
authors.initials: D
authors.lastname: Kokel
authors.forename: Jijie
authors.initials: J
authors.lastname: Chai
authors.forename: Wenyu
authors.initials: W
authors.lastname: Li
authors.forename: Aidong
authors.initials: A
authors.lastname: Han
authors.forename: Lin
authors.initials: L
authors.lastname: Chen
authors.forename: Ding
authors.initials: D
authors.lastname: Xue
authors.forename: Yigong
authors.initials: Y
authors.lastname: Shi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins; D029742:Caenorhabditis elegans Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D017124:Conserved Sequence; D018360:Crystallography, X-Ray; D004591:Electrophoresis, Polyacrylamide Gel; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011518:Proto-Oncogene Proteins / Q000737:chemistry* / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012097:Repressor Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D019076:Transgenes
chemical_list: D051017:Apoptosis Regulatory Proteins; D029742:Caenorhabditis elegans Proteins; D002135:Calcium-Binding Proteins; C089224:Ced-4 protein, C elegans; C087233:Ced-9 protein, C elegans; C112486:EGL-1 protein, C elegans; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins