Correlation between self-association modes and GTPase activation of dynamin

• Published in: Journal of Protein Chemistry 1999-04, Vol.18 (3), p.277-290
• Main Authors: Binns, D D, Barylko, B, Grichine, N, Atkinson, M A, Helms, M K, Jameson, D M, Eccleston, J F, Albanesi, J P
• Format: Article
• Language: English
• Subjects: Animals; Brain - enzymology; Cattle; Clathrin; Coated vesicles; Conformation; Dose-Response Relationship, Drug; Dynamin; Dynamins; Enzymatic activity; Enzymes; GTP Phosphohydrolases - metabolism; Guanosine triphosphatases; Internalization; Kinetics; Lattice vibration; Microtubules - metabolism; Models, Biological; Molecular biology; Oligomerization; Proteins; Self-assembly; Self-association; Sodium Chloride - pharmacology; Time Factors; Tubulin - metabolism; Ultracentrifugation
• ISSN: 0277-8033; 1572-3887; 1573-4943
• DOI: 10.1023/a:1021083211267

The GTPase activity of dynamin is obligatorily coupled, by a mechanism yet unknown, to the internalization of clathrin-coated endocytic vesicles. Dynamin oligomerizes in vitro and in vivo and both its mechanical and enzymatic activities appear to be mediated by this self-assembly. In this study we demonstrate that dynamin is characterized by a tetramer/monomer equilibrium with an equilibrium constant of 1.67 x 10(17) M(-3). Stopped-flow fluorescence experiments show that the association rate constant for 2'(3')-O-N-methylanthraniloyl (mant)GTP is 7.0 x 10(-5) M(-1) s(-1) and the dissociation rate constant is 2.1 s(-1), whereas the dissociation rate constant for mantdeoxyGDP is 93 s(-1). We also demonstrate the cooperativity of dynamin binding and GTPase activation on a microtubule lattice. Our results indicate that dynamin self-association is not a sufficient condition for the expression of maximal GTPase activity, which suggests that dynamin molecules must be in the proper conformation or orientation if they are to form an active oligomer.