"Studying ion channels with two-dimensional vibrational spectroscopy"
Two-dimensional infrared spectroscopy (2D IR) is a powerful tool for extracting structural and dynamical information from a wide range of biological systems. I will describe our recent collaboration with experimentalists in which we successfully addressed key questions in potassium (K+) channel biophysics. K+ channels are transmembrane proteins that regulate the passage of K+ ions through cell membranes. The selectivity filter is the narrowest part of the pathway of ions through the channel. It plays a determining role in the remarkably high ion selectivity and transport rates. Despite decades of work the precise mechanistic details of the transport through ion channels are still elusive. In a recent collaboration with experimentalists, we performed simulations to design 2D IR experiments that can provide a close view of the ions inside the selectivity filter of a bacterial K+ channel (KcsA). By comparing simulations and experiments we showed that only one of the hypothetical ion transport mechanisms is compatible with experimental spectra in the closed conductive state of the channel. I will end by presenting our newest simulations showing a unique capability of 2D IR spectroscopy to provide insights into selectivity of K+ channels