Fig. 7.

Drp1 VD intercalates into the membrane core to bind CL but does not induce stable nonbilayer phases. (A) Negative-stain transmission EM of the Drp1 ssNMR sample shows Drp1-induced membrane tubulation and GTP-dependent local membrane constriction (yellow boxes; arrow points to a constricted region). (B) Static ³¹P ssNMR of DOPC/PE/CL liposomes in the presence (blue) and absence (dashed) of bound Drp1 shows the characteristic line shape of a liquid crystalline lipid bilayer. Binding by Drp1 in presence of GTP (Bottom) leads to a narrowing of the overall ³¹P line shape, indicating an increased lipid headgroup wobble. (C) ³¹P MAS ssNMR of DOPC/CL liposomes without (Top) and with (Bottom) bound VD shows two peaks corresponding to the DOPC and CL lipid species. (D) T₂ relaxation measurements reveal different amounts of dephasing for VD-bound CL versus PC. (E) Upon VD binding, the T₂ relaxation curve for DOPC is unchanged (Bottom), but the T₂ time for CL is significantly shortened (Top), indicating a slowing down of CL lateral diffusion by bound VD. (F–H) GTPase activity of Drp1 incubated with liposomes containing: (F) CL species of differing acyl chain lengths and saturation in a 85/15 DOPC/CL species context, (G) an increasing mole fraction of DOPE in the DOPC/CL background, and (H) an increasing concentration of CL in the presence of 20% DOG. Data are averages ± SD.