Apoptosis-inducing factor (AIF) is a mitochondrial flavoprotein with pro-life and pro-death activities, which plays critical roles in mitochondrial energy metabolism and caspase-independent apoptosis. Defects in AIF structure or expression can cause mitochondrial abnormalities leading to mitochondrial defects and neurodegeneration. The mechanism of AIF-induced apoptosis was extensively investigated, whereas the mitochondrial function of AIF is poorly understood. A unique feature of AIF is the ability to form a tight, air-stable charge-transfer (CT) complex upon reaction with NADH and to undergo a conformational switch leading to dimerization, proposed to be important for its vital and lethal functions. Although some aspects of interaction of AIF with NAD(+)/H have been analyzed, its precise mechanism is not fully understood. We investigated how the oxidized and photoreduced wild-type and G307A and -E variants of murine AIF associate with NAD(+)/H and nicotinamide mononucleotide (NMN(+)/H) to determine the role of the adenylate moiety in the binding process. Our results indicate that (i) the adenylate moiety of NAD(+)/H is crucial for the association with AIF and for the subsequent structural reorganization of the complex, but not for protein dimerization, (ii) FAD reduction rather than binding of NAD(+)/H to AIF initiates conformational rearrangement, and (iii) alteration of the adenylate-binding site by the G307E (equivalent to a pathological G308E mutation in human AIF) or G307A replacements decrease the affinity and association rate of NAD(+)/H, which, in turn, perturbs CT complex formation and protein dimerization but has no influence on the conformational switch in the regulatory peptide.

Key role of the adenylate moiety and integrity of the adenylate-binding site for the NAD(+)/H binding to mitochondrial apoptosis-inducing factor / L. Sorrentino, A.M. Calogero, V. Pandini, M.A. Vanoni, I.F. Sevrioukova, A. Aliverti. - In: BIOCHEMISTRY. - ISSN 0006-2960. - 54:47(2015 Dec 01), pp. 6996-7009.

Key role of the adenylate moiety and integrity of the adenylate-binding site for the NAD(+)/H binding to mitochondrial apoptosis-inducing factor

L. Sorrentino
Primo
;
A.M. Calogero
Secondo
;
V. Pandini;M.A. Vanoni;A. Aliverti
Ultimo
2015

Abstract

Apoptosis-inducing factor (AIF) is a mitochondrial flavoprotein with pro-life and pro-death activities, which plays critical roles in mitochondrial energy metabolism and caspase-independent apoptosis. Defects in AIF structure or expression can cause mitochondrial abnormalities leading to mitochondrial defects and neurodegeneration. The mechanism of AIF-induced apoptosis was extensively investigated, whereas the mitochondrial function of AIF is poorly understood. A unique feature of AIF is the ability to form a tight, air-stable charge-transfer (CT) complex upon reaction with NADH and to undergo a conformational switch leading to dimerization, proposed to be important for its vital and lethal functions. Although some aspects of interaction of AIF with NAD(+)/H have been analyzed, its precise mechanism is not fully understood. We investigated how the oxidized and photoreduced wild-type and G307A and -E variants of murine AIF associate with NAD(+)/H and nicotinamide mononucleotide (NMN(+)/H) to determine the role of the adenylate moiety in the binding process. Our results indicate that (i) the adenylate moiety of NAD(+)/H is crucial for the association with AIF and for the subsequent structural reorganization of the complex, but not for protein dimerization, (ii) FAD reduction rather than binding of NAD(+)/H to AIF initiates conformational rearrangement, and (iii) alteration of the adenylate-binding site by the G307E (equivalent to a pathological G308E mutation in human AIF) or G307A replacements decrease the affinity and association rate of NAD(+)/H, which, in turn, perturbs CT complex formation and protein dimerization but has no influence on the conformational switch in the regulatory peptide.
neurodegeneration; mitochondriopathy; apoptosis; mitochondrion; redox sensor; oxidative phosphorylation; NAD+; NADH; flavin nucleotide; flavoprotein; flavoenzyme; enzyme mechanism; protein engineering; charge-transfer complex; protein quaternary structure; protein dimerization; protein ligand binding
Settore BIO/10 - Biochimica
Settore BIO/11 - Biologia Molecolare
1-dic-2015
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/343238
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