Structure-function analysis of the ATP-driven glycolipid efflux pump DevBCA reveals complex organization with TolC/HgdD

In Gram-negative bacteria, trans-envelope efflux pumps have periplasmic membrane fusion proteins (MFPs) as essential components. MFPs act as mediators between outer membrane factors (OMFs) and inner membrane factors (IMFs). In this study, structure-function relations of the ATP-driven glycolipid efflux pump DevBCA-TolC/HgdD from the cyanobacterium Anabaena sp. PCC 7120 were analyzed. The binding of the MFP DevB to the OMF TolC absolutely required the respective tip-regions. The interaction of DevB with the IMF DevAC mainly involved the beta-barrel and the lipoyl domain. Efficient binding to DevAC and TolC, substrate recognition and export activity by DevAC were dependent on stable DevB hexamers. Structured summary of protein interactions: DevB binds to DevB by surface plasmon resonance (View interaction) DevC and DevA physically interact with DevB by surface plasmon resonance (View interaction) TolC binds to DevB by surface plasmon resonance (1, 2) DevB and DevB bind by molecular sieving (View interaction) (C) 2013 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.