The Oscp Subunit of Atp Synthase is a Dimer in Solution: Implications for the Druggability of Mitochondrial Permeability Transition

Abstract

Defects in the regulation of mitochondrial Permeability Transition (PT) are involved in a wide range of human disorders, including cancer, neurodegenerative diseases, heart diseases, and aging. To date, the molecular details behind PT remain elusive, severely limiting the therapeutic treatment of the pathologies associated with this phenomenon. The ATP synthase subunit Oligomycin Sensitivity Conferral Protein (OSCP) is indicated as the key site for the PT regulation, emerging as a promising target for pharmacological strategies. However, the study of OSCP as a potential PT-related therapeutic target has been so far hindered by the poor properties of the isolated protein in solution. Here, we use an integrated approach based on Nuclear Magnetic Resonance (NMR), Small Angle X-ray Scattering (SAXS) and Mass Spectrometry under native conditions (nMS) to demonstrate that the isolated OSCP subunit is not affected by nonspecific aggregation, but it is involved in a dimerization equilibrium. By the analysis of the anchoring region between the OSCP subunit and the b subunit of the ATP synthase, we identified a peptide mimicking the sequence of the C-terminal helix of the b subunit (b-CT) and capable to interfere with the OSCP dimerization equilibrium, stabilizing the monomeric state of the protein. Our characterization of the OSCP subunit paves the way for future therapeutic strategies against PT-related disorders, possibly improving our understanding of the mechanisms behind PT dysregulation in human diseases.

Keywords: OSCP ATP synthase subunit, protein NMR, Mitochondrial Permeability Transition, SAXS, nMS