title: Structural insights into the coenzyme mediated monomer-dimer transition of the pro-apoptotic apoptosis inducing factor.
abstract: The 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.
authors.affiliation: Departamento de Bioquímica y Biología Molecular y Celular, ‡Instituto de Biocomputación y Física de Sistemas Complejos (BIFI)-Joint Unit BIFI-IQFR (CSIC), and §Laboratorio de Microscopias Avanzadas, Instituto de Nanociencia de Aragón (INA), Universidad de Zaragoza , Zaragoza, Spain.
authors.forename: Patricia
authors.initials: P
authors.lastname: Ferreira
authors.forename: Raquel
authors.initials: R
authors.lastname: Villanueva
authors.forename: Marta
authors.initials: M
authors.lastname: Martínez-Júlvez
authors.forename: Beatriz
authors.initials: B
authors.lastname: Herguedas
authors.forename: Carlos
authors.initials: C
authors.lastname: Marcuello
authors.forename: Patricio
authors.initials: P
authors.lastname: Fernandez-Silva
authors.forename: Lauriane
authors.initials: L
authors.lastname: Cabon
authors.forename: Juan A
authors.initials: JA
authors.lastname: Hermoso
authors.forename: Anabel
authors.initials: A
authors.lastname: Lostao
authors.forename: Santos A
authors.initials: SA
authors.lastname: Susin
authors.forename: Milagros
authors.initials: M
authors.lastname: Medina
mesh_terms: D017209:Apoptosis; D051033:Apoptosis Inducing Factor / Q000737:chemistry* / Q000235:genetics; D018360:Crystallography, X-Ray; D006801:Humans; D007700:Kinetics; D008958:Models, Molecular; D009154:Mutation; D009243:NAD / Q000737:chemistry*; D011401:Promoter Regions, Genetic; D011487:Protein Conformation; D055503:Protein Multimerization
chemical_list: D051033:Apoptosis Inducing Factor; D009243:NAD