Structural Basis Of Oligomerization In Activated GTPase Domain Of Arabidopsis Thaliana Dynamin-related Protein

The process of endocytosis is through which cells internalize portions of plasmamembrane along with extracellular substances, is very important for cell physiologyand biochemistry, counterbalances delivery of new membrane to that cell surface,controls the signaling output of receptors, mediates cell drawing nutrients.Clathrin-coated vesicle (CCV) formation is an initial step of endocytosis, and inanimal cells is largely achieved by dynamins. Dynamin, which catalyses membranefission during clathrin-mediated endocytosis, is the prototypical member of a familyof multidomain GTPases involved in fission and remodeling of multiple organelles.Recent studies have shown that dynamin alone can catalyze fission of membranetubules and vesicle formation from planar lipid templates. Thus, dynamin appears tobe a self-sufficient fission machine.Dynamin is is the prototypical member of a family of large GTPases, theircommon characteristic are low affinity GTP, high basal turnover and the propensityfor oligomerization into helical arrays. in vivo,purified dynamin is tetramer, alsopossess basal GTPase activity, and on negatively charged lipid templates speedyself-assembly into helical arrays, which GTPase activity is stimulated exceeding100-fold.in vivo, GTP hydrolysis is required for dynamin-catalysed membrane fission,however, in vivo is paradoxical which disassembly of dynamin helices anddissociation of dynamin subunits from the membrane. The underlying mechanisms ofdynamin’s basal and assembly-stimulated activities are unknown and its catalyticmachinery has yet to be identified.Plant specific dynamin-like proteins play crucial role in cell plate formation,endo-or exocytosis, protein sorting to the vacuole and plasma membrane, anddivision of mitochondria and chloroplasts. However, little is known of its molecularmechanisms in plant cells. To elucidate the function and mechanism of plant specificdynamin-like proteins, in this paper, detailed study the Arabidopsis dynamin-relatedprotein1A (AtDRP1A), which is is a member of the dynamin superfamily ofGTPases that plays a critical role, and essential for proper maturation of the cell plate during cytokinesis. and recent studies have also suggested that it functions like animaldynamin in Clathrin-Mediated Endocytosis (CME), we present here the2.6and3.5different comformational crystal structure of GTPase domain fused with itsGTPase Effector domain (GED) of Arabidopsis dynamin-related protein1A(AtDrp1A) in GDP-associated conformation. Based on the results of gel-filtration andcrystal structure shows that GTPase-GED should exist as a homodimer in solution,adding their different substrates and BSE swing angle, divide this two differentconformation into prefission and postfission, which can explain how the GTPasedynamin catalyzes membrane fission by forming a collar around the necks ofclathrin-coated pits. Two different comformational crystal structure of AtDrp1Areveals dynamin’s catalytic machinery and explains how assembly-stimulated GTPhydrolysis is achieved through G domain dimerization. The prefission Structuralcomparison to postfission structure reveals key conformational changes that promoteG domain dimerization and stimulated hydrolysis. The structure of the GTPase-GEDfusion protein dimer provides insight into the mechanisms underlyingdynamin-catalysed membrane fission.