Transport of drugs by the multidrug transporter AcrB involves an access and a deep binding pocket that are separated by a switch-loop
10.1073/pnas.1114944109
Crossref journal-article
Proceedings of the National Academy of Sciences
Proceedings of the National Academy of Sciences (341)
Abstract

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.

Bibliography

Eicher, T., Cha, H., Seeger, M. A., Brandstätter, L., El-Delik, J., Bohnert, J. A., Kern, W. V., Verrey, F., Grütter, M. G., Diederichs, K., & Pos, K. 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, 109(15), 5687–5692.

Authors 11
  1. Thomas Eicher (first)
  2. Hi-jea Cha (additional)
  3. Markus A. Seeger (additional)
  4. Lorenz Brandstätter (additional)
  5. Jasmin El-Delik (additional)
  6. Jürgen A. Bohnert (additional)
  7. Winfried V. Kern (additional)
  8. François Verrey (additional)
  9. Markus G. Grütter (additional)
  10. Kay Diederichs (additional)
  11. Klaas M. Pos (additional)
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Dates
Type When
Created 13 years, 5 months ago (March 27, 2012, 12:28 a.m.)
Deposited 3 years, 2 months ago (June 7, 2022, 4:24 a.m.)
Indexed 1 month, 3 weeks ago (July 8, 2025, 3:09 p.m.)
Issued 13 years, 5 months ago (March 26, 2012)
Published 13 years, 5 months ago (March 26, 2012)
Published Online 13 years, 5 months ago (March 26, 2012)
Published Print 13 years, 4 months ago (April 10, 2012)
Funders 0

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@article{Eicher_2012, title={Transport of drugs by the multidrug transporter AcrB involves an access and a deep binding pocket that are separated by a switch-loop}, volume={109}, ISSN={1091-6490}, url={http://dx.doi.org/10.1073/pnas.1114944109}, DOI={10.1073/pnas.1114944109}, number={15}, journal={Proceedings of the National Academy of Sciences}, publisher={Proceedings of the National Academy of Sciences}, author={Eicher, Thomas and Cha, Hi-jea and Seeger, Markus A. and Brandstätter, Lorenz and El-Delik, Jasmin and Bohnert, Jürgen A. and Kern, Winfried V. and Verrey, François and Grütter, Markus G. and Diederichs, Kay and Pos, Klaas M.}, year={2012}, month=mar, pages={5687–5692} }