Fig. 6.

Alteration of membrane permeability by the E protein. (A) Growth kinetics of E. coli strain DH5α expressing GST, GST-N or GST-E. (B) Hygromycin B permeability assay in bacterial cells. Cultures of the gene-transformed E. coli were induced by IPTG to express GST (lanes 1, 2), GST-N (lanes 3, 4) or GST-E (lanes 5 to 8). At 1 h post-induction, cells were incubated in the presence (+) or absence (−) of 1 mM of hygromycin B for 15 min and radiolabeled with [³⁵S]methionine/cysteine for 15 min. Cells were collected and lysed in sample buffer and analyzed by SDS–12% PAGE, followed by Coomassie blue staining (left panel) or autoradiography (right panel). Lanes 1 and 2, cells expressing GST alone; lanes 3 and 4, cells expressing PRRSV N fused with GST (GST-N); lanes 5 and 6, cells expressing PRRSV E fused with GST (GST-E); lanes 7 and 8, double amount of loading for cells expressing GST-E. Arrows indicate GST, GST-N or GST-E.