Fig. 6. Tetracycline affects the membrane independently of ribosome inhibition.

Strain PG112 carries the tet-4 mutation, a point mutation in the ribosomal protein S10 that renders ribosomes insensitive to tetracycline. Strain SG82 carries the tetL tetracycline efflux pump. Cells were treated with 1x MIC of tetracycline (16 µg/ml for PG112, 100 µg/ml for SG82) for 30 min prior to membrane staining with Nile red and microscopy. See Supplementary Fig. 18 for titration of tetracycline concentrations. a Microscopy images of Nile red-stained cells. Scale bar 2 µm. b Quantification of microscopy images showing the percentage of spotty (= membrane-stressed) cells. Quantification was done manually. Sample size was ≥100 individual cells per condition. Error bars show standard deviation of the mean from three replicate experiments. Circles indicate individual datapoints.