Correcting the uppS31 missense mutation restores cell shape at 42°C. (A, C, and E) Phase-contrast micrographs of MG1655 (A and E) or CS109 (C) cells carrying wild-type genes (uppS+ and ispH+) or mutations (uppS31 and ispH269), as noted. MG1655 cells containing uppS31 combined with wild-type ispH did not grow when subcultured in liquid medium (Lethal). Cells were grown in LB at 30°C or 42°C, as noted, to an OD600 of 0.5 to 0.6 and were photographed by phase-contrast microscopy. The scale bar represents 3 μm. (B, D, and F) Histograms of the forward scatter of 100,000 live cells as shown in panels A, C, and E. The mean of the forward scatter is reported in arbitrary units to the right of each curve, and the vertical dashed line represents the mean forward scatter of the uppS+
ispH+ mutant strain for each group. (C and D) Strains CS109 (uppS31 ispH269) (green curve), SKCS156 (uppS+ ispH269) (blue curve), SKCS183 (uppS31 ispH+) (orange curve), and SKCS195 (uppS+ ispH+) (red curve) all with IS-idi. (A, B, E, and F) Strains MG1655 (uppS+ ispH+) (red curve), SKCS173 (uppS31 ispH+) (orange curve), SKMG143 (uppS+ ispH269) (blue curve), and SKMG197 (uppS31 ispH269) (green curve) all with no IS upstream of idi. S, UppS; H, IspH; +, wild type; 31, UppSW31R; 269, IspHS269A.