Design, Optimization, and Structural Characterization of an Apoptosis-Inducing Factor Peptide Targeting Human Cyclophilin A to Inhibit Apoptosis Inducing Factor-Mediated Cell Death
L. Russo, Fabiola Mascanzoni, Biancamaria Farina, Amalia M. Dolga, Alessandra Monti, Andrea Caporale, Carsten Culmsee, Roberto Fattorusso, Menotti Ruvo, Nunzianna Doti
Abstract
Blocking the interaction between the apoptosis-inducing factor (AIF) and cyclophilin A (CypA) by the AIF fragment AIF(370–394) is protective against glutamate-induced neuronal cell death and brain injury in mice. Starting from AIF(370–394), we report the generation of the disulfide-bridged and shorter variant AIF(381–389) and its structural characterization by nuclear magnetic resonance (NMR) in the free and CypA-bound state. AIF(381–389) in both the free and bound states assumes a β-hairpin conformation similar to that of the fragment in the AIF protein and shows a highly reduced conformational flexibility. This peptide displays a similar in vitro affinity for CypA, an improved antiapoptotic activity in cells and an enhanced proteolytic stability compared to the parent peptide. The NMR-based 3D model of the AIF(381–389)/CypA complex provides a better understanding of the binding hot spots on both the peptide and the protein and can be exploited to design AIF/CypA inhibitors with improved pharmacokinetic and pharmacodynamics features.