Similarities between Exogenously- and Endogenously-Induced Envelope Stress: The Effects of a New Antibacterial Molecule, TPI1609-10
Figure 8
Comparing the effect of SM10 treatment or OmpC overexpression in aerobically- and anaerobically- growing E. coli.
MG1655 cells were grown for 3 hr at 37°C, with shaking. Anaerobic cultures were grown using an anaerobic hood and/or in a closed-vial-system, in both cases after sparging the O2 gas with argon. The legend for panels A, B and C is shown in panel B. The legend for panels D, E and F is shown in panel E; in addition, the presence of O2 is indicated both under the X axes as well as by the darker shading of the bars denoting aerobically-grown cells. (A) Lethality of SM10 treatments was not greatly affected by lack of oxygen. (B) SM10 caused about 40% fewer DNA breaks in MG1655 cells grown anaerobically, as quantified by TUNEL assay. (C) SM10-induced formation of ROS in MG1655 cells, visualized by the HPF assay, is negligible in anaerobically–grown MG1655 cells. (D) Overexpression of OmpC but not of PurE causes lethality in either aerobically- or anaerobically-growing cells. (E) Over-expression of OmpC anaerobically results in about half the DNA breaks observed compared to aerobically, as quantified by TUNEL assay. (F) Reactive oxygen species are produced in aerobically-growing cells over-expressing OmpC, but not PurE.