GH3, a novel proapoptotic domain in Drosophila Grim, promotes a mitochondrial death pathway.
Grim encodes a protein required for programmed cell death in Drosophila. The Grim N-terminus induces apoptosis by disrupting IAP blockage of caspases; however, N-terminally-deleted Grim retains pro apoptotic activity. We describe GH3, a 15 amino acid internal Grim domain absolutely required for its proapoptotic activity and sufficient to induce cell death when fused to heterologous carrier proteins. A GH3 homology region is present in the Drosophila proapoptotic proteins Reaper and Sickle. The GH3 domain and the homologous regions in Reaper and Sickle are predicted to be structured as amphipathic alpha-helixes. During apoptosis induction, Grim colocalizes with mitochondria and cytochrome c in a GH3-dependent but N-terminal- and caspase activity-independent manner. When Grim is overexpressed in vivo, both the N-terminal and the GH3 domains are equally necessary, and cooperate for apoptosis induction. The N-terminal and GH3 Grim domains thus activate independent apoptotic pathways that synergize to induce programmed cell death efficiently.
Clavería
Cristina
C
Departamento de Inmunología y Oncología, Centro Nacional de Biotecnología, CSIC-UAM, Campus de Cantoblanco, E-28049 Madrid, Spain.
Caminero
Eva
E
Martínez-A
Carlos
C
Campuzano
Sonsoles
S
Torres
Miguel
M
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D030801:Animals, Genetically Modified; D017209:Apoptosis / Q000502:physiology*; D020169:Caspases / Q000502:physiology; D002478:Cells, Cultured; D003574:Cytochrome c Group / Q000502:physiology; D029721:Drosophila Proteins / Q000737:chemistry / Q000502:physiology*; D004331:Drosophila melanogaster / Q000166:cytology*; D005260:Female; D008297:Male; D008928:Mitochondria / Q000502:physiology*; D008969:Molecular Sequence Data; D009479:Neuropeptides / Q000737:chemistry / Q000502:physiology*; D010641:Phenotype; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000502:physiology; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship
D003574:Cytochrome c Group; D029721:Drosophila Proteins; D009479:Neuropeptides; D011993:Recombinant Fusion Proteins; C108881:grim protein, Drosophila; D020169:Caspases