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

To confirm the relevance of this pentameric structure and the effect of HMA and amiloride on the channel activity, results were obtained by transient expression of SARS-CoV E in human embryonic kidney 293 (HEK-293) cells. Transfected cells produced significantly higher channel activity than the controls (Fig. 7A) . The whole-cell patch clamp recording (Fig. 7B ) reveal moderate inward (negative current) and large outward (positive current) conductance. The same figure shows significantly smaller 'control' currents obtained with cells transfected with the vector alone, or non-transfected HEK-293 cells. ACSF (artificial cerebrospinal fluid) was used as bath solution, which contained a high concentration of NaCl (124 mM), whereas the internal solution contained a high concentration of potassium ion (145 mM), close to the intracellular medium under physiological conditions. Under our recording conditions, the estimated equilibrium potentials, E Na and E k , were 65 mV and 287 mV, respectively. Strong selectivity for either of these cations would produce a reversal potential (i.e., zero current) near their corresponding equilibrium potential. If the channel was poorly selective, the reversal potential would have a value somewhere in between E Na and E k , whereas no selectivity would produce a reversal potential in the mid point between these values (,210 mV). The observed value of reversal potential at ,0 mV (Fig. 7B) indicates low selectivity between sodium and potassium, with perhaps a mild preference for sodium. This is consistent with previous results performed in planar lipid bilayers with synthetic E proteins [35, 36] .