Structural Biology of Presynaptic Scaffolds

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DESCRIPTION (provided by applicant): The macroscopic morphological changes in spine structure, and number of synapses that accompany exposure to drugs of abuse such as cocaine and amphetamines indicate that synaptic plasticity plays an important role in the re-wiring of an addicted brain. Descending to a molecular level, cues for changes in the circuitry are issued through changes in synaptic activity, which critically depends on the cellular process of endocytosis because of its direct involvement in receptor clearance from the surface and neurotramsitter vesicle/transporter recycling. The goal of this exploratory study is to enable mechanistic understanding of fundamental synaptic processes, such as endocytosis, by opening the dynamic interface between cellular membranes and the cytoplasm to structural exploration. As a starting point, our work will focus on BAR- and F-BAR-domain proteins whose ability to induce, and to stabilize membrane curvature places them at a strategic intersection between membrane remodeling, vesicle fission, and cytoskeletal re-arrangements. Using purified BAR-/F-BAR-domains and their corresponding full-length proteins (endophilin, amphiphysin, syndapin 1, FBP17 and CIP4), we seek to obtain samples for structure determination by electron cryomicroscopy, in which these proteins are bound to lipid bilayers, either alone or in complex with downstream interaction partners like the fission GTPase dynamin, the cytoskeletal regulators Cdc42 and neural Wiskott-Aldrich-Syndrome Protein (N-WASP). Exposure to drugs of abuse such as cocaine and amphetamines results in lasting morphological changes in some parts of the brain, indicating that synaptic plasticity plays an important role in the biology of addiction. At the molecular level, cues for remodeling of synapses stem from changes in synaptic activities, which at the molecular level critically depend on the cellular process of endocytosis. To advance our basic understanding of the complex processes underlying the biology of addiction, this study ultimately aims at revealing, at a molecular scale, the mechanisms through which protein complexes that are critically important for endocytotic processes contribute to synaptic plasticity.