Fig. 1

Visualizing the AcrAB–TolC efflux pump in the E. coli cell envelope. a A single slice from a tomogram of E. coli. The condensed materials shown inside of the cell are inclusion bodies resulting from membrane protein overexpression. b Zoomed inside view of the cell envelope containing the AcrAB–TolC pump which is indicated by the red rectangle. c Corresponding three-dimensional annotation of b showing the outer membrane (OM; blue), the inner membrane (IM; blue), peptidoglycan (PG; yellow), and the AcrAB–TolC pump (cyan). d Top view of the cell envelope containing the AcrAB–TolC pumps which appear as ring-shaped densities (indicated by the red circle)