Fig. 1.

Crystal structures of multidrug efflux transporters exemplified by AcrAB-TolC[55, 107, 119] and EmrD[70] of E. coli and Sav1866 of S. aureus.[56] Instead of AcrA, we show the recent complete structure of its homologue MexA.[108] See text and the relevant references for details of the structural properties of these transporters. The figures were drawn by Pymol (http://www.pymol.org) by using the coordinate files 2DRD (AcrB), 2V4D (MexA), 2VDE (TolC, an open form), 2GFP (EmrD), and 2HYD (Sav1866), obtained from the Protein Data Bank. The models were colored in rainbow colors (N-terminus blue, C-terminus red) and the approximate positions of membrane bilayers are indicated by horizontal lines. Note that for oligomeric proteins, the rainbow color was selected from the N-terminus of one protomer all the way to the C-terminus of another protomer. Proteins were positioned so that the external portion is up in the figure. The bound minocycline in the AcrB structure is shown in red rods (highlighted by a green arrow).