Part of the tripartite efflux system AcrEF-TolC. Involved in the efflux of indole and organic solvents. Part of the tripartite efflux system AcrEF-TolC, which is composed of an inner membrane transporter, AcrF, a periplasmic membrane fusion protein, AcrE, and an outer membrane component, TolC. The complex forms a large protein conduit and can translocate molecules across both the inner and outer membranes (Probable). Induced by LeuO, part of the acrEF operon. Belongs to the membrane fusion protein (MFP) (TC 8.A.1) family.