Energy transduction and alternating access of the mammalian ABC transporter P-glycoprotein

Brandy Verhalen, Reza Dastvan, Sundarapandian Thangapandian, Yelena Peskova, Hanane A. Koteiche, Robert K. Nakamoto, Emad Tajkhorshid, Hassane S. McHaourab

Research output: Contribution to journalArticlepeer-review

Abstract

ATP binding cassette (ABC) transporters of the exporter class harness the energy of ATP hydrolysis in the nucleotide-binding domains (NBDs) to power the energetically uphill efflux of substrates by a dedicated transmembrane domain (TMD). Although numerous investigations have described the mechanism of ATP hydrolysis and defined the architecture of ABC exporters, a detailed structural dynamic understanding of the transduction of ATP energy to the work of substrate translocation remains elusive. Here we used double electron-electron resonance and molecular dynamics simulations to describe the ATP- and substrate-coupled conformational cycle of the mouse ABC efflux transporter P-glycoprotein (Pgp; also known as ABCB1), which has a central role in the clearance of xenobiotics and in cancer resistance to chemotherapy. Pairs of spin labels were introduced at residues selected to track the putative inward-facing to outward-facing transition. Our findings illuminate how ATP energy is harnessed in the NBDs in a two-stroke cycle and elucidate the consequent conformational motion that reconfigures the TMD, two critical aspects of Pgp transport mechanism. Along with a fully atomistic model of the outward-facing conformation in membranes, the insight into Pgp conformational dynamics harmonizes mechanistic and structural data into a novel perspective on ATP-coupled transport and reveals mechanistic divergence within the efflux class of ABC transporters.

Original languageEnglish (US)
Pages (from-to)738-741
Number of pages4
JournalNature
Volume543
Issue number7647
DOIs
StatePublished - Mar 30 2017

ASJC Scopus subject areas

  • General

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