Coronavirus E protein forms ion channels with functionally and structurally-involved membrane lipids

Coronavirus (CoV) envelope (E) protein ion channel activity was determined in channels formed in planar lipid bilayers by peptides representing either the transmembrane domain of severe acute respiratory syndrome CoV (SARS-CoV) E protein, or the full-length E protein. Both of them formed a voltage independent ion conductive pore with symmetric ion transport properties. Mutations N15A and V25F located in the transmembrane domain prevented the ion conductivity. E protein derived channels showed no cation preference in non-charged lipid membranes, whereas they behaved as pores with mild cation selectivity in negatively-charged lipid membranes. The ion conductance was also controlled by the lipid composition of the membrane. Lipid charge also regulated the selectivity of a HCoV-229E E protein derived peptide. These results suggested that the lipids are functionally involved in E protein ion channel activity, forming a protein–lipid pore, a novel concept for CoV E protein ion channel entity.

► SARS-CoV envelope (E) protein formed ion conductive pores in lipid bilayers.
► Pores showed voltage independent ion conductance and symmetric ion transport.
► Conductance and selectivity of SARS-CoV E ion pore were controlled by lipid charge.
► Selectivity of HCoV-229E E protein ion channel was also regulated by lipid charge.
► Novelty: lipids are functionally and structurally involved in Coronavirus E ion pore.