The architecture of AcrAB−TolC. (A) The cryoEM structures of a fully assembled AcrAB−TolC complex with open form of TolC (PDI ID: 5NG5) and a AcrB trimer (PDI ID: 6BAJ) with several important transmembrane helixes and subdomains in an AcrB protomer (31, 34), and (B) the conformation cycle of the three distinct protomers within trimeric AcrB, which each protomer goes through the rotation of three states termed loose (L), tight (T), and open (O) (48-50, 92).
