Paper detail

Forces from Lipids and Ionic Diffusion: Probing lateral membrane effects by an optimized filter region of voltage dependent K+ channels

We investigate the possible influence of poly unsaturated fatty acids (PUFAs) in the lipid bilayer of cell membranes on the conduction properties of the selectivity filter of voltage gated ion channels. Any change of this conductivity can have major consequences on electrical signalling in brain and other cells. At the microscopic level a change in the concentration of PUFAs can cause a change in the pressure distribution within the lipid bilayer, and this in turn can lead to a change in the length of the selectivity filter. In order to estimate the consequences this might entail for the ion channel's conductivity we performed high resolution molecular dynamics (MD) simulations of the passage of K+ ions and H2O molecules through the selectivity filter of the KcsA potassium ion channel. Our results show that a change in length of the selectivity filter of as little as 4%, independent of whether the filter is made longer or shorter, will reduce the K+ ion current by around 50%. And further squeezing or stretching by about 10% can effectively stop the current. For instructive purposes and to facilitate further interpretation of the results, we give details of the force models employed in the MD simulations. We finally discuss the present results in the context of possible effects of membrane lipid compositions on Kv ion permeation.