Minimal Viral Potassium Channels for Studying Protein/Lipid Interaction

Abstract

The channel proteins from Chlorella viruses are miniature versions of K+ channels. They are the structural equivalents of the pore module of complex K+ channels from eukaryotes and they include the selectivity filter, the cavity and gates. The channel KcvNTS is with only 82 amino acids particularly small and molecular dynamics simulations suggest that the channel is quasi fully embedded in a di-myristoylphosphatidylcholin (C14) lipid bilayer [1]. This close interaction between the channel protein and its lipid environment offers the possibility to examine lipid/protein interaction for a channel pore in a systematic manner. For this purpose we reconstituted the purified channel protein in lipid bilayers with different chain lengths, phospholipid head groups and in the absence and presence of detergents or cholesterol. The analysis of single channel activity shows that the membrane composition affects channel gating but not the unitary conductance. Most interesting is a voltage dependency of the channel, which is introduced by the presence of cholesterol, detergent or bilayers with long chain length.Reference1. Braun, C.J., et al., Viral potassium channels as a robust model system for studies of membrane-protein interaction. Biochim Biophys Acta, 2013.