3gd4
Crystal structure of the reduced, NAD-bound form of murine apoptosis inducing factor
Structural highlights
FunctionAIFM1_MOUSE Functions both as NADH oxidoreductase and as regulator of apoptosis. In response to apoptotic stimuli, it is released from the mitochondrion intermembrane space into the cytosol and to the nucleus, where it functions as a proapoptotic factor in a caspase-independent pathway. In contrast, functions as an antiapoptotic factor in normal mitochondria via its NADH 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 (By similarity). Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedApoptosis-inducing factor (AIF) is a bifunctional mitochondrial flavoprotein critical for energy metabolism and induction of caspase-independent apoptosis, whose exact role in normal mitochondria remains unknown. Upon reduction with NADH, AIF undergoes dimerization and forms tight, long-lived FADH(2)-NAD charge-transfer complexes (CTC) that are proposed to be functionally important. To obtain a deeper insight into structure/function relations and redox mechanism of this vitally important protein, we determined the X-ray structures of oxidized and NADH-reduced forms of naturally folded recombinant murine AIF. Our structures reveal that CTC with the pyridine nucleotide is stabilized by (i) pi-stacking interactions between coplanar nicotinamide, isoalloxazine, and Phe309 rings; (ii) rearrangement of multiple aromatic residues in the C-terminal domain, likely serving as an electron delocalization site; and (iii) an extensive hydrogen-bonding network involving His453, a key residue that undergoes a conformational switch to directly interact with and optimally orient the nicotinamide for charge transfer. Via the His453-containing peptide, redox changes in the active site are transmitted to the surface, promoting AIF dimerization and restricting access to a primary nuclear localization signal through which the apoptogenic form is transported to the nucleus. Structural findings agree with biochemical data and support the hypothesis that both normal and apoptogenic functions of AIF are controlled by NADH. Redox-linked conformational dynamics in apoptosis-inducing factor.,Sevrioukova IF J Mol Biol. 2009 Jul 31;390(5):924-38. Epub 2009 May 15. PMID:19447115[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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