Channelrhodopsins (ChRs) are light-gated ion channels used in optogenetics to selectively control and monitor the activities of individual neurons in living tissue. While an understanding of structure vs. function relationships would facilitate efforts to engineer and extend ChRs’ utility to depolarize membranes of excitable cells (other than neurons) with light, little is known about the mechanism of cation permeation through the protein. Here we present the results of molecular dynamics simulations of the closed and open-state C1C2 chimera and ChR2 channels in lipids and electrolyte solution. First, we discuss the proton transport pathway. Next, we analyze the influence of the mutation of a novel site, N258, on ChR channel gating and ion selectivity. This work contributes to the deciphering of the atomistic details of ChRs’ function, explaining the mechanisms of ion permeation and gating to facilitate rational design of ChR variants. This work is supported by an NSF Award (CHE-1301072) and Sandia's LDRD program. Sandia National Laboratories is a multi-program laboratory operated by Sandia Corp., a wholly owned subsidiary of Lockheed Martin Corp., for the U.S. DoE's NNSA under contract DE-AC04-94AL85000.

Channelrhodopsin: Proton transport and mutation studies

251st National Meeting (2016)

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