title: Intramembrane congestion effects on lysenin channel voltage-induced gating.
abstract: All cell membranes are packed with proteins. The ability to investigate the regulatory mechanisms of protein channels in experimental conditions mimicking their congested native environment is crucial for understanding the environmental physicochemical cues that may fundamentally contribute to their functionality in natural membranes. Here we report on investigations of the voltage-induced gating of lysenin channels in congested conditions experimentally achieved by increasing the number of channels inserted into planar lipid membranes. Typical electrophysiology measurements reveal congestion-induced changes to the voltage-induced gating, manifested as a significant reduction of the response to external voltage stimuli. Furthermore, we demonstrate a similar diminished voltage sensitivity for smaller populations of channels by reducing the amount of sphingomyelin in the membrane. Given lysenin's preference for targeting lipid rafts, this result indicates the potential role of the heterogeneous organization of the membrane in modulating channel functionality. Our work indicates that local congestion within membranes may alter the energy landscape and the kinetics of conformational changes of lysenin channels in response to voltage stimuli. This level of understanding may be extended to better characterize the role of the specific membrane environment in modulating the biological functionality of protein channels in health and disease.
authors.affiliation: Department of Physics, Boise State University, Boise, ID, 83725, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Krueger
authors.affiliation: Department of Physics, Boise State University, Boise, ID, 83725, USA.
authors.forename: Sheenah
authors.initials: S
authors.lastname: Bryant
authors.affiliation: Department of Physics, Boise State University, Boise, ID, 83725, USA.
authors.forename: Nisha
authors.initials: N
authors.lastname: Shrestha
authors.affiliation: Department of Physics, Boise State University, Boise, ID, 83725, USA.
authors.forename: Tyler
authors.initials: T
authors.lastname: Clark
authors.affiliation: Department of Physics, Boise State University, Boise, ID, 83725, USA.
authors.forename: Charles
authors.initials: C
authors.lastname: Hanna
authors.affiliation: Department of Physics, St. Francis Xavier University, Antigonish, NS, B2G 2W5, Canada.
authors.forename: David
authors.initials: D
authors.lastname: Pink
authors.affiliation: Department of Physics, Boise State University, Boise, ID, 83725, USA. danielfologea@boisestate.edu.
authors.forename: Daniel
authors.initials: D
authors.lastname: Fologea
mesh_terms: D015640:Ion Channel Gating; D008051:Lipid Bilayers / Q000737:chemistry; D021962:Membrane Microdomains / Q000737:chemistry* / Q000378:metabolism; D008564:Membrane Potentials; D013109:Sphingomyelins / Q000737:chemistry; D014118:Toxins, Biological / Q000737:chemistry* / Q000378:metabolism
chemical_list: D008051:Lipid Bilayers; D013109:Sphingomyelins; D014118:Toxins, Biological; C107040:lysenin
keywords: Crowding; Lipid rafts; Lysenin; Open probability; Sphingomyelin; Voltage-gating