Structure and Inhibition of the SARS Coronavirus Envelope Protein Ion Channel

Pervushin, Konstantin; Tan, Edward; Parthasarathy, Krupakar; Lin, Xin; Jiang, Feng Li; Yu, Dejie; Vararattanavech, Ardcharaporn; Soong, Tuck Wah; Liu, Ding Xiang; Torres, Jaume

SARS-CoV E in plasma membranes is oriented with the Nterminus facing the cytoplasm [47] , whereas the C-terminus of the ETM would face the extracellular domain. The latter therefore would be the likely HMA binding site in our patch clamp experiment, although the fact that HMA partitions into detergent micelles, and presumably into lipid bilayers, suggests that both N and C-termini of ETM could be accessible to the drug. The weak inhibition observed for amiloride is consistent with our NMR data, because addition of amiloride to ETM showed an increase in line broadening, but only small changes in peak positions, suggesting a global perturbation of protein structure but not a specific interaction. Finally, although the chemical shifts induced by AMT (not shown) were similar to those observed for HMA, we did not observe NOEs between AMT and ETM. This is not unexpected; in contrast with what we observed in a lysineflanked ETM peptide [37, 38] , the in vitro ion channel activity observed for ETM without flanking lysines, i.e., like the one used herein, was not inhibited by AMT [38] .