Apoptosis inducing factor (AIF): a phylogenetically old, caspase-independent effector of cell death.
Although much emphasis has been laid on the role of caspase in cell death, recent data indicate that, in many instances, mammalian cell death is caspase-independent. Thus, in many examples of mammalian cell death the 'decision' between death and life is upstream or independent of caspase activation. Similarly, it is unclear whether PCD of plants and fungi involves the activation of caspase-like enzymes, and no caspase-like gene has thus far been cloned in these phyla. Apoptosis inducing factor (AIF) is a new mammalian, caspase-independent death effector which, upon apoptosis induction, translocates from its normal localization, the mitochondrial intermembrane space, to the nucleus. Once in the nucleus, AIF causes chromatin condensation and large scale DNA fragmentation to fragments of approximately 50 kbp. The AIF cDNA from mouse and man codes for a protein which possesses three domains (i) an amino-terminal presequence which is removed upon import into the intermembrane space of mitochondria; (ii) a spacer sequence of approximately 27 amino acids; and (iii) a carboxyterminal 484 amino acid oxidoreductase domain with strong homology to oxidoreductases from other vertebrates (X. laevis), non-vertebrate animals (C. elegans, D. melanogaster), plants, fungi, eubacteria, and archaebacteria. Functionally important amino acids involved in the interaction with the prosthetic groups flavin adenine nucleotide and nicotinamide adenine nucleotide are strongly conserved between AIF and bacterial oxidoreductase. Several eukaryotes possess a similar domain organisation in their AIF homologs, making them candidates to be mitochondrial oxidoreductases as well as caspase-independent death effectors. The phylogenetic implications of these findings are discussed.
Lorenzo
H K
HK
Massachusetts General Hospital, Harvard Medical School, Boston MA 02114, USA.
Susin
S A
SA
Penninger
J
J
Kroemer
G
G
D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis; D051033:Apoptosis Inducing Factor; D051017:Apoptosis Regulatory Proteins; D017173:Caenorhabditis elegans; D029742:Caenorhabditis elegans Proteins; D020169:Caspases; D016923:Cell Death; D003546:Cysteine Endopeptidases; D019143:Evolution, Molecular; D005420:Flavoproteins / Q000145:classification; D015801:Helminth Proteins; D006801:Humans; D008322:Mammals; D008565:Membrane Proteins / Q000145:classification; D051379:Mice; D008969:Molecular Sequence Data; D010802:Phylogeny; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D017421:Sequence Analysis
C494829:AIFM1 protein, human; D051033:Apoptosis Inducing Factor; D051017:Apoptosis Regulatory Proteins; D029742:Caenorhabditis elegans Proteins; C087233:Ced-9 protein, C elegans; D005420:Flavoproteins; D015801:Helminth Proteins; D008565:Membrane Proteins; C494830:AIFM1 protein, mouse; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D020169:Caspases; D003546:Cysteine Endopeptidases; C089223:ced-3 protein, C elegans