LARGE SCALE MD SIMULATIONS OF ANESTHETIC EFFECTS ON ION CHANNELS

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. This renewal proposal seeks a continuing support from NCSA to ensure the progress of our on-going research funded by NIH (R01GM056257-11, R01GM66358-09, R37GM049202). The ultimate goal of our study is to understand the molecular mechanisms of general anesthesia through our combined experimental and computational efforts. Our immediate objective is to elucidate how general anesthetics interact with their putative targets and affect protein structures and motions. Our central hypothesis is that general anesthetics alter functions of these proteins by modulating functional relevant protein motions. As reflected in our research progress report in section III, we have worked on neuronal nAChRs and Gloeobacter violaceus pentameric ligand-gated ion channel (GLIC) in the presence and absence of anesthetic halothane through MD simulations. Parallel to our computational studies, we have conducted many sets of structural and functional measurements on GLIC to determine where general anesthetics bind to GLIC and how they inhibit GLIC channel. We can turn GLIC into an anion channel through mutation at several critical residues and determine whether anesthetics inhibit or potentiate Cl? permeable GLIC (GLICCl). In this application, we have three aims. Aim 1 is to determine the important factors that can keep GLIC in an open-channel state during long MD simulations. Aim 2 is to correlate the redistribution of global dynamics profiles due to anesthetic binding with changes in channel conductance using long-timescale simulations. In Aim 3, we will determine the potential of mean force (PMF) for transporting a single Cl? ion along the GLIC channel and (B) determine the underlying cause of the experimentally observed potentiation or inhibition of GLIC channel by anesthetics. Collectively, we will integrate new experimental findings into our computational studies and reveal underlying mechanisms of anesthetic action on the pentameric ligand gated ion channels.