The OSCP Subunit of ATP Synthase is a Dimer in Solution: Strategy to Induce the Monomeric Protein as a New Tool for Drug Discovery.

The F-ATP synthase subunit Oligomycin Sensitivity Conferral Protein (OSCP) contributes to the structural and functional coupling between the F catalytic and the F transmembrane domains of the synthase. A body of literature suggests that OSCP is also a potential pharmacological target, as it mediates interactions with both proteins and small molecules capable of influencing ATP synthase activity and mitochondrial Permeability Transition (PT). However, the possibility of further exploring this aspect has been so far hindered by the poor properties of the isolated protein in solution, as reported by previous studies. 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. This study offers valuable insights on the structural properties of the isolated OSCP subunit in solution, opening new avenues for future pharmacological studies and a more thorough comprehension of the emerging therapeutic potential of this protein.