NSF/MCB-BSF: Collaborative Research: Towards development of the structural determinants of the Glutamate receptor gating regulation by auxiliary membrane anchored proteins

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High cognitive functions, including quantitative reasoning, learning and memory, originate in the human brain as a result of communication between complex networks of neurons connected through synapses. The key molecular element of this synaptic connection is the ionotropic glutamate receptor (iGluR), a protein in the postsynaptic neuronal membrane that conducts electrical signals to deliver messages from the presynaptic neuron. This process of neurotransmission is modulated by a variety of auxiliary proteins that bind to glutamate receptors. This project will illuminate how different auxiliary proteins interact with the glutamate receptor and with each other to initiate and modulate communication between neurons. This study enhances our knowledge of the molecular underpinnings of brain function. The research will involve undergraduate and graduate students, providing an educational environment and training opportunities at the forefront of brain research. Outreach activities involving local high schools and colleges are planned as well to promote diverse participation in STEM fields.It is increasingly recognized that the majority of proteins operate in cells within dynamically formed and re-formed complexes. This is especially important for signaling receptor proteins, such as ionotropic receptors in the brain that conduct electrical current through postsynaptic membranes to facilitate fast communication between neurons. The AMPA receptors (AMPAR) - a subtype of iGluRs - mediate the fastest excitatory neurotransmission in the mammalian brain. Correspondingly, regulation of AMPAR trafficking, localization and function is the key mechanism determining synaptic strength and plasticity that underlies high cognitive brain functions, such as learning and memory. It has been discovered recently that synaptic AMPARs function as complexes with a multitude of auxiliary proteins. This project aims to characterize molecular interactions of AMPARs with the cys-knot AMPAR modulating proteins (CKAMPs) and their interplay with the transmembrane AMPAR regulatory proteins (TARPs). A large collection of AMPAR and CKAMP mutants will be employed to identify interaction domains and specific residues involved in receptor regulation. Computational structural modeling including docking and molecular dynamics simulations will be employed to guide further determination of the protein-protein interfaces, which will be tested by electrophysiology experiments, and to generate and analyze candidate constructs for successful structure determination by cryo-EM. This collaborative effort, combining complementary approaches and continuous exchange of information and reagents, may provide the synergy needed to reach a new level of understanding of AMPAR regulation. In addition to providing fundamental insights into AMPAR gating and regulation, the results of this study will also serve as a roadmap for investigating AMPAR-mediated processes in synaptic physiology.This award was co-funded by the Division of Molecular and Cellular Biosciences, the Division of Integrative Organismal Systems, and the Rules of Life Venture Fund.This collaborative US/Israel project is supported by the US National Science Foundation and the Israeli Binational Science Foundation.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.