PNNL

Abstract

Stochastic and inhomogeneous conformational changes often regulate the dynamics of ion channels. Such inhomegeniety makes it difficult, if not impossible; to be characterized not only by ensemble-averaged experiments by also by single-channel patch recording that does not specifically probe the associated conformational changes. Here, we report on our work using a new approach combining single-molecule fluorescence spectroscopy and single-channel patch recording to investigate conformational changes of individual gramicidin ion channels. We observed fluorescence self-quenching and single-pair fluorescence resonance energy transfer (spFRET) from dye-labeled gramicidin dimmers within the channel was open. We also observed that the efficiency of self-quenching and spFRETS is widely distributed when the channel is closed. Our results strongly suggest a hitherto undetectable correlation of multiple conformational states of the gramicidin channel associated with closed and open states under physiologically-related conditions.