Figure 5. Model for dynamin GTP cycle conformational changes.

a, Mapping of dynamin shibire and sushi mutations. b, Nucleotide-dependent dynamin conformations. The GTPase core domains (red) are in the same orientation. Left, GTP-bound state with open BSE conformation of dynamin as fitted into the GMPPCP-bound electron microscopic reconstruction shown in Fig. 4. Right, transition state of dynamin obtained by superposition of the BSE residues 291–312 and 727–743 of our structure on the corresponding residues of the GDP•AlF₄ ⁻-bound GTPase–CGED fusion dimer (PDB accession no. 2×2E)¹⁰. Transition from open to closed BSE conformation results in movement of stalk domains. c, Model for Dyn1 ΔPRD GTP-bound helix. The BSE is opened to allow GTPase–GTPase dimer formation. d, GTP hydrolysis closes the BSE and adopts the conformation of the GDP•AlF₄ ⁻-bound transition state. This results in a substantial global constriction of the helical oligomeric assembly causing membrane deformation and scission. e, Schematic of how the proposed GTP hydrolysis triggered BSE conformational change is transmitted to oligomerized stalk domains.