Structure of a zosuquidar and UIC2-bound human-mouse chimeric ABCB1

Amer Alam, Raphael Küng, Julia Kowal, Robert A. McLeod, Nina Tremp, Eugenia V. Broude, Igor B. Roninson, Henning Stahlberg, Kaspar P. Locher

Research output: Contribution to journalArticlepeer-review

66 Scopus citations

Abstract

The multidrug transporter ABCB1 (P-glycoprotein) is an ATP-binding cassette transporter that has a key role in protecting tissues from toxic insult and contributes to multidrug extrusion from cancer cells. Here, we report the near-atomic resolution cryo- EM structure of nucleotide-free ABCB1 trapped by an engineered disulfide cross-link between the nucleotide-binding domains (NBDs) and bound to the antigen-binding fragment of the human-specific inhibitory antibody UIC2 and to the third-generation ABCB1 inhibitor zosuquidar. Our structure reveals the transporter in an occluded conformation with a central, enclosed, inhibitor-binding pocket lined by residues from all transmembrane (TM) helices of ABCB1. The pocket spans almost the entire width of the lipid membrane and is occupied exclusively by two closely interacting zosuquidar molecules. The external, conformational epitope facilitating UIC2 binding is also visualized, providing a basis for its inhibition of substrate efflux. Additional cryo- EM structures suggest concerted movement of TM helices from both halves of the transporters associated with closing the NBD gap, as well as zosuquidar binding. Our results define distinct recognition interfaces of ABCB1 inhibitory agents, which May be exploited for therapeutic purposes.

Original languageEnglish (US)
Pages (from-to)E1973-E1982
JournalProceedings of the National Academy of Sciences of the United States of America
Volume115
Issue number9
DOIs
StatePublished - Feb 27 2018
Externally publishedYes

Bibliographical note

Funding Information:
ACKNOWLEDGMENTS. We thank the staff at the Scientific Center for Optical and Electron Microscopy at ETH Zürich, especially Peter Tittman, as well as Kenneth N. Goldie and Ariane Fecteau-LeFebvre from Center for Cellular Imaging and Nano Analytics for help with EM data collection. We also acknowledge Bernadette Prinz for help with protein expression and cell culture work. This research was supported by a European Molecular Biology Organization long-term postdoctoral fellowship (to A.A.), National Institutes of Health Grant P20 GM 109091 (to E.V.B.), grants from the Swiss Cancer League (to K.P.L.), and the Swiss National Science Foundation through National Center of Competence in Research Structural Biology and TransCure.

Funding Information:
We thank the staff at the Scientific Center for Optical and Electron Microscopy at ETH Zürich, especially Peter Tittman, as well as Kenneth N. Goldie and Ariane Fecteau-LeFebvre from Center for Cellular Imaging and Nano Analytics for help with EM data collection. We also acknowledge Bernadette Prinz for help with protein expression and cell culture work. This research was supported by a European Molecular Biology Organization long-term postdoctoral fellowship (to A.A.), National Institutes of Health Grant P20 GM 109091 (to E.V.B.), grants from the Swiss Cancer League (to K.P.L.), and the Swiss National Science Foundation through National Center of Competence in Research Structural Biology and TransCure.

Keywords

  • ABC transporter
  • Cryo-EM
  • Mechanism
  • Small-molecule inhibitors
  • Structure

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