Interaction of Prohibitin with the inner of mitochondrial membrane

Prohibitin (PHB) is a heterodimer forming a multimeric ring in the intermembrane space at the inner mitochondrial membrane. PHB directs the cell’s energy production. Each of the two PHBs has an N-terminal helix thought to anchor the protein to the membranes. Our aim is to characterize the anchoring of PHB to the membrane by studying the two peptides corresponding to the intermembrane sequences of the dimer. Preliminary results collected showed the importance of lipid membrane composition in particular cardiolipin (CL, present at high concentration in mitochondrial membranes), but led to 3 unexpected findings: a seemingly opposite action of both N-terminal helices, slow kinetics of interaction, and concentration-threshold effects. The X-ray reflectivity experiment we propose for ID10 will (i) locate and quantify the 2 N-terminal helices in the membrane at various incubation times, (ii) elucidate possible synergisms between the peptides and (iii) resolve the role of CL.