Enhancement of dynamin polymerization and GTPase activity by Arc/Arg3.1

• Published in: Biochimica et biophysica acta Vol. 1850; no. 6; pp. 1310 - 1318
• Main Authors: Byers, Christopher E., Barylko, Barbara, Ross, Justin A., Southworth, Daniel R., James, Nicholas G., Taylor, Clinton A., Wang, Lei, Collins, Katie A., Estrada, Armando, Waung, Maggie, Tassin, Tara C., Huber, Kimberly M., Jameson, David M., Albanesi, Joseph P.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.06.2015
• Subjects: Animals; Arc/Arg3.1; Cytoskeletal Proteins - chemistry; Cytoskeletal Proteins - genetics; Cytoskeletal Proteins - metabolism; cytoskeleton; dendrites; Dynamin; Dynamin I - metabolism; Dynamin II - metabolism; Dynamin III - metabolism; dynamins; Dynamins - chemistry; Dynamins - metabolism; endocytosis; Enzyme Activation; fluorescence; gel chromatography; genes; glutamate receptors; GTPase; guanosine triphosphate; Guanosine Triphosphate - metabolism; Histidine - metabolism; Humans; Hydrolysis; ionic strength; light scattering; Mice; Nerve Tissue Proteins - chemistry; Nerve Tissue Proteins - genetics; Nerve Tissue Proteins - metabolism; neuroplasticity; oligomerization; Oligopeptides - metabolism; Polymerization; polymers; Rats; Recombinant Fusion Proteins - metabolism; Self-assembly; sodium chloride; Sodium Chloride - chemistry; spectroscopy; synaptic vesicles; Temperature; Time Factors; turbidity; Self-assembly; Arc/Arg3.1; GTPase; Dynamin
• ISSN: 0304-4165; 0006-3002; 1872-8006
• DOI: 10.1016/j.bbagen.2015.03.002

The Activity-regulated cytoskeleton-associated protein, Arc, is an immediate-early gene product implicated in various forms of synaptic plasticity. Arc promotes endocytosis of AMPA type glutamate receptors and regulates cytoskeletal assembly in neuronal dendrites. Its role in endocytosis may be mediated by its reported interaction with dynamin 2, a 100kDa GTPase that polymerizes around the necks of budding vesicles and catalyzes membrane scission. Enzymatic and turbidity assays are used in this study to monitor effects of Arc on dynamin activity and polymerization. Arc oligomerization is measured using a combination of approaches, including size exclusion chromatography, sedimentation analysis, dynamic light scattering, fluorescence correlation spectroscopy, and electron microscopy. We present evidence that bacterially-expressed His6-Arc facilitates the polymerization of dynamin 2 and stimulates its GTPase activity under physiologic conditions (37°C and 100mM NaCl). At lower ionic strength Arc also stabilizes pre-formed dynamin 2 polymers against GTP-dependent disassembly, thereby prolonging assembly-dependent GTP hydrolysis catalyzed by dynamin 2. Arc also increases the GTPase activity of dynamin 3, an isoform of implicated in dendrite remodeling, but does not affect the activity of dynamin 1, a neuron-specific isoform involved in synaptic vesicle recycling. We further show in this study that Arc (either His6-tagged or untagged) has a tendency to form large soluble oligomers, which may function as a scaffold for dynamin assembly and activation. The ability of Arc to enhance dynamin polymerization and GTPase activation may provide a mechanism to explain Arc-mediated endocytosis of AMPA receptors and the accompanying effects on synaptic plasticity. •Arc binds to dynamin 2 and promotes its polymerization.•Arc stabilizes dynamin polymers against GTP-dependent disassembly.•GTPase activation is prolonged in Arc-stabilized dynamin polymers.•The N-terminal portion of Arc is responsible for dynamin activation.