Fig 4.

Enhanced Redox Sensor Green staining is dependent on viroporin activity. Redox Sensor Green (RSG) staining of BL21(DE3) E. coli bearing expression vectors encoding either wild-type NSP4 aa 47–146 or the viroporin-deficient mutant NSP4 aa 47–146 ASDASA, in which residues 75 to 80 are mutated from IFNTLL to ASDASA. Cells were left untreated (dark gray), or NSP4 expression was induced with 1 mM IPTG (light gray). At 1 h postinduction, cells were stained with RSG for 10 min at 37°C and then analyzed by flow cytometry for the RSG mean fluorescence intensity (MFI). Samples were tested in triplicate, and error bars represent standard deviations. There was no statistically significant difference in RSG staining between uninduced and induced cells expressing the ASDASA viroporin mutant.