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Crystal structure of the reduced human Apoptosis inducing factor complexed with NAD
Structural highlights
DiseaseAIFM1_HUMAN Defects in AIFM1 are the cause of combined oxidative phosphorylation deficiency type 6 (COXPD6) [MIM:300816. It is a mitochondrial disease resulting in a neurodegenerative disorder characterized by psychomotor delay, hypotonia, areflexia, muscle weakness and wasting.[1] [2] FunctionAIFM1_HUMAN Probable oxidoreductase that has a dual role in controlling cellular life and death; during apoptosis, it is translocated from the mitochondria to the nucleus to function as a proapoptotic factor in a caspase-independent pathway, while in normal mitochondria, it functions as an antiapoptotic factor via its oxidoreductase activity. The soluble form (AIFsol) found in the nucleus induces 'parthanatos' i.e. caspase-independent fragmentation of chromosomal DNA. Interacts with EIF3G,and thereby inhibits the EIF3 machinery and protein synthesis, and activates casapse-7 to amplify apoptosis. Plays a critical role in caspase-independent, pyknotic cell death in hydrogen peroxide-exposed cells. Binds to DNA in a sequence-independent manner.[3] [4] [5] Publication Abstract from PubMedThe apoptosis-inducing factor (AIF) is a mitochondrial-flavoprotein that, after cell death induction, is distributed to the nucleus to mediate chromatinolysis. In mitochondria, AIF is present in a monomer-dimer equilibrium that after reduction by NADH gets displaced toward the dimer. The crystal structure of the human AIF (hAIF):NAD(H)-bound dimer revealed one FAD and, unexpectedly, two NAD(H) molecules per protomer. A 1:2 hAIF:NAD(H) binding stoichiometry was additionally confirmed in solution by using surface plasmon resonance. The here newly discovered NAD(H)-binding site includes residues mutated in human disorders, and accommodation of the coenzyme in it requires restructuring of a hAIF portion within the 509-560 apoptogenic segment. Disruption of interactions at the dimerization surface by production of the hAIF E413A/R422A/R430A mutant resulted in a nondimerizable variant considerably less efficiently stabilizing charge-transfer complexes upon coenzyme reduction than WT hAIF. These data reveal that the coenzyme-mediated monomer-dimer transition of hAIF modulates the conformation of its C-terminal proapoptotic domain, as well as its mechanism as reductase. These observations suggest that both the mitochondrial and apoptotic functions of hAIF are interconnected and coenzyme controlled: a key information in the understanding of the physiological role of AIF in the cellular life and death cycle. Structural insights into the coenzyme mediated monomer-dimer transition of the pro-apoptotic apoptosis inducing factor.,Ferreira P, Villanueva R, Martinez-Julvez M, Herguedas B, Marcuello C, Fernandez-Silva P, Cabon L, Hermoso JA, Lostao A, Susin SA, Medina M Biochemistry. 2014 Jul 1;53(25):4204-15. doi: 10.1021/bi500343r. Epub 2014 Jun, 20. PMID:24914854[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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