STRUCTURE-FUNCTION ANALYSIS OF COXSACKIE B3 VIRUS PROTEIN 2B

Expression of poliovirus protein 2B in mammalian cells inhibits protei n secretion and increases the susceptibility of the cells to hygromyci n B, consistent with the increase in plasma membrane permeability seen during poliovirus infection (J. R. Doedens and K. Kirkegaard, EMBO J. 14, 894-907, 1995). We report here that expression of protein 2B of t he closely related coxsackie B3 virus (CBV3) leads to the same biochem ical alterations. Analysis of several mutant CBV3 28 proteins that con tain mutations in a predicted cationic amphipathic alpha-helix (F. J. M. van Kuppeveld, J. M. D. Ga[ama, J. Zoll, P. J. J. C. van den Hurk, and W. J. G. Melchers, J. Virol. 70, 3876-3886, 1996) demonstrated tha t the integrity of this domain is crucial for both biochemical functio ns of 2B. Mutations in a second hydrophobic domain (F. J. M. van Kuppe veld, J. M. D. Galama, J. Zoll, and W. J. G. Melchers, J. Virol. 69, 7 782-7790, 1995), on the other hand, are more disruptive to the ability of CBV3 28 to inhibit protein secretion than to increase membrane per meability. Therefore, inhibition of protein secretion is not merely a consequence of the membrane changes that increase uptake of hygromycin B. The existence of mutations that interfere with virus growth but do not impair the ability of 28 to inhibit protein secretion or increase membrane permeability argues for additional functions of protein 2B. (C) 1997 Academic Press