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

Department of Physics, Laboratory of Molecular Biophysics, Universitat Jaume I, 12071 Castellón, Spain.
Virology (Impact Factor: 3.32). 07/2012; 432(2):485-94. DOI: 10.1016/j.virol.2012.07.005
Source: PubMed


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.

Download full-text


Available from: Antonio Alcaraz
  • Source

    Full-text · Chapter · Nov 2011
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Zoonotic coronaviruses, including the one that caused the Severe Acute Respiratory Syndrome (SARS) cause significant morbidity and mortality in humans. No specific therapy for any human coronavirus is available, making vaccine development critical for protection against these viruses. We previously showed that recombinant SARS-CoV (Urbani strain-based) lacking E protein expression (rU-ΔE) provided good but not perfect protection in young mice against challenge with virulent mouse-adapted SARS-CoV (MA15). To improve vaccine efficacy, we developed a second set of E-deleted vaccine candidates, on an MA15 background (rMA15-ΔE). rMA15-ΔE is safe, causing no disease in 6 week, 12 month or 18 month BALB/c mice. Immunization with this virus completely protected mice of three ages from lethal disease and effected more rapid virus clearance. Compared to rU-ΔE, rMA15-ΔE immunization resulted in significantly greater neutralizing antibody and SARS-CoV-specific CD4 and CD8 T cell responses. After challenge, inflammatory cell infiltration, edema and lung destruction were decreased in the lungs of rMA15-ΔE compared to rU-ΔE-immunized 12 month old mice. Collectively, these results show that immunization with a species-adapted attenuated coronavirus lacking E protein expression is safe and provides optimal immunogenicity and long-term protection against challenge with lethal virus. This approach will be generally useful for development of vaccines protective against human coronaviruses as well as against coronaviruses that cause disease in domestic and companion animals.
    Full-text · Article · Apr 2013 · Journal of Virology
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A partial characterization of the ion channels formed by the SARS coronavirus (CoV) envelope (E) protein was previously reported [C. Verdiá-Báguena et al., 2012]. Here, we provide new significant insights on the involvement of lipids in the structure and function of the CoV E protein channel on the basis of three series of experiments. First, reversal potential measurements over a wide range of pH allows the dissection of the contributions to channel selectivity coming from ionizable residues of the protein transmembrane domain and also from the negatively charged groups of diphytanoyl phosphatidylserine (DPhPS) lipid. The corresponding effective pKa's are consistent with the model pKa's of the acidic residues candidates for titration. Second, the change of channel conductance with salt concentration reveals two distinct regimes (Donnan-controlled electrodiffusion and bulk-like electrodiffusion) fully compatible with the outcomes of selectivity experiments. Third, by measuring channel conductance in mixtures of neutral diphytanoyl phosphatidylcholine (DPhPC) lipids and negatively charged DPhPS lipids in low and high salt concentrations we conclude that the protein-lipid conformation in the channel is likely the same in charged and neutral lipids. Overall, the whole set of experiments supports the proteolipidic structure of SARS-CoV E channels and explains the large difference in channel conductance observed between neutral and charged membranes.
    Full-text · Article · May 2013 · Biochimica et Biophysica Acta
Show more