Permanent URL to this publication: http://dx.doi.org/10.5167/uzh-62599
Eicher, Thomas; Cha, Hi-jea; Seeger, Markus A; Brandstätter, Lorenz; El-Delik, Jasmin; Bohnert, Jürgen A; Kern, Winfried V; Verrey, François; Grütter, Markus G; Diederichs, Kay; Pos, Klaas M (2012). Transport of drugs by the multidrug transporter AcrB involves an access and a deep binding pocket that are separated by a switch-loop. Proceedings of the National Academy of Sciences of the United States of America (PNAS), 109(15):5687-5692.
AcrAB-TolC is the major efflux protein complex in Escherichia coli extruding a vast variety of antimicrobial agents from the cell. The inner membrane component AcrB is a homotrimer, and it has been postulated that the monomers cycle consecutively through three conformational stages designated loose (L), tight (T), and open (O) in a concerted fashion. Binding of drugs has been shown at a periplasmic deep binding pocket in the T conformation. The initial drug-binding step and transport toward this drug-binding site has been elusive thus far. Here we report high resolution structures (1.9-2.25 Å) of AcrB/designed ankyrin repeat protein (DARPin) complexes with bound minocycline or doxorubicin. In the AcrB/doxorubicin cocrystal structure, binding of three doxorubicin molecules is apparent, with one doxorubicin molecule bound in the deep binding pocket of the T monomer and two doxorubicin molecules in a stacked sandwich arrangement in an access pocket at the lateral periplasmic cleft of the L monomer. This access pocket is separated from the deep binding pocket apparent in the T monomer by a switch-loop. The localization and conformational flexibility of this loop seems to be important for large substrates, because a G616N AcrB variant deficient in macrolide transport exhibits an altered conformation within this loop region. Transport seems to be a stepwise process of initial drug uptake in the access pocket of the L monomer and subsequent accommodation of the drug in the deep binding pocket during the L to T transition to the internal deep binding pocket of the T monomer.
|Item Type:||Journal Article, refereed, original work|
|Communities & Collections:||04 Faculty of Medicine > Institute of Biochemistry|
07 Faculty of Science > Institute of Biochemistry
04 Faculty of Medicine > Institute of Physiology
07 Faculty of Science > Institute of Physiology
04 Faculty of Medicine > Center for Integrative Human Physiology
|DDC:||570 Life sciences; biology|
610 Medicine & health
|Deposited On:||04 Jun 2012 13:54|
|Last Modified:||03 Dec 2012 12:12|
|Publisher:||National Academy of Sciences|
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