How the N-terminal Domain of the OSCP Subunit of Bovine F1Fo-ATP Synthase Interacts with the N-terminal Region of an Alpha Subunit

The peripheral stalk of ATP synthase acts as a stator holding the α3β3 catalytic subcomplex and the membrane subunit a against the torque of the rotating central stalk and attached c ring. In bovine mitochondria, the N-terminal domain of the oligomycin sensitivity conferral protein (OSCP-NT; residues 1–120) anchors one end of the peripheral stalk to the N-terminal tails of one or more α subunits of the F1 subcomplex. Here, we present an NMR characterisation of the interaction between OSCP-NT and a peptide corresponding to residues 1–25 of the α-subunit of bovine F1-ATPase. The interaction site contains adjoining hydrophobic surfaces of helices 1 and 5 of OSCP-NT binding to hydrophobic side-chains of the α-peptide.