title: G domain dimerization controls dynamin's assembly-stimulated GTPase activity.
abstract: Dynamin is an atypical GTPase that catalyses membrane fission during clathrin-mediated endocytosis. The mechanisms of dynamin's basal and assembly-stimulated GTP hydrolysis are unknown, though both are indirectly influenced by the GTPase effector domain (GED). Here we present the 2.0 A resolution crystal structure of a human dynamin 1-derived minimal GTPase-GED fusion protein, which was dimeric in the presence of the transition state mimic GDP.AlF(4)(-).The structure reveals dynamin's catalytic machinery and explains how assembly-stimulated GTP hydrolysis is achieved through G domain dimerization. A sodium ion present in the active site suggests that dynamin uses a cation to compensate for the developing negative charge in the transition state in the absence of an arginine finger. Structural comparison to the rat dynamin G domain reveals key conformational changes that promote G domain dimerization and stimulated hydrolysis. The structure of the GTPase-GED fusion protein dimer provides insight into the mechanisms underlying dynamin-catalysed membrane fission.
authors.affiliation: Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, Maryland 20892, USA.
authors.forename: Joshua S
authors.initials: JS
authors.lastname: Chappie
authors.forename: Sharmistha
authors.initials: S
authors.lastname: Acharya
authors.forename: Marilyn
authors.initials: M
authors.lastname: Leonard
authors.forename: Sandra L
authors.initials: SL
authors.lastname: Schmid
authors.forename: Fred
authors.initials: F
authors.lastname: Dyda
mesh_terms: D017607:Aluminum Compounds / Q000378:metabolism; D000595:Amino Acid Sequence; D055162:Biocatalysis; D020134:Catalytic Domain / Q000235:genetics; D017124:Conserved Sequence; D018360:Crystallography, X-Ray; D034284:Dynamin I / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation; D005459:Fluorides / Q000378:metabolism; D020558:GTP Phosphohydrolases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006153:Guanosine Diphosphate / Q000031:analogs & derivatives / Q000378:metabolism; D006801:Humans; D006868:Hydrolysis; D008958:Models, Molecular; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D012964:Sodium / Q000378:metabolism
chemical_list: D017607:Aluminum Compounds; D006153:Guanosine Diphosphate; C050992:tetrafluoroaluminate; D012964:Sodium; D034284:Dynamin I; D020558:GTP Phosphohydrolases; D005459:Fluorides