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. Author manuscript; available in PMC: 2023 Jan 6.
Published in final edited form as: Structure. 2021 Sep 9;30(1):107–113.e3. doi: 10.1016/j.str.2021.08.008

Figure 4. Model for the transmission of ligand-induced conformational signals from AcrB to TolC through AcrA during substrate transport.

Figure 4.

(A) Schematic view of the AcrAB-TolC efflux pump. (B) Zoomed in view of the boxed area in (A). The red oval indicates the interaction zone between AcrA protomer II and AcrB, and the blue stars mark the subregions that undergoes conformational changes. The MP domain of AcrA protomer II, anchored into the inner membrane, connects to the AcrB PC2 domain which has substantial conformational changes during transition from the binding to the extrusion state, and from the extrusion to the access state. The conformational change can be communicated through AcrA to TolC to affect the channel gating. OM, outer membrane; IM, inner membrane; PG, peptidoglycan.