Structure-guided probing of the leukotriene C4 binding site in human multidrug resistance protein 1 (MRP1; ABCC1)

Gwenaëlle Conseil, May Arama-Chayoth, Yossi Tsfadia, Susan P.C. Cole

Research output: Contribution to journalArticlepeer-review

Abstract

The human multidrug resistance protein 1 (hMRP1) transporter is implicated in cancer multidrug resistance as well as immune responses involving its physiologic substrate, glutathione (GSH)-conjugated leukotriene C4 (LTC4). LTC4 binds a bipartite site on hMRP1, which a recent cryoelectron microscopy structure of LTC4-bound bovine Mrp1 depicts as composed of a positively charged pocket and a hydrophobic (H) pocket that binds the GSH moiety and surrounds the fatty acid moiety, respectively, of LTC4. Here, we show that single Ala and Leu substitutions of H-pocket hMRP1-Met1093 have no effect on LTC4 binding or transport. Estrone 3-sulfate transport is also unaffected, but both hMRP1-Met1093 mutations eliminate estradiol glucuronide transport, demonstrating that these steroid conjugates have binding sites distinct from each other and from LTC4. To eliminate LTC4 transport by hMRP1, mutation of 3 H-pocket residues was required (W553/M1093/W1246A), indicating that H-pocket amino acids are key to the vastly different affinities of hMRP1 for LTC4 vs. GSH alone. Unlike organic anion transport, hMRP1-mediated drug resistance was more diminished by Ala than Leu substitution of Met1093. Although our findings generally support a structure in which H-pocket residues bind the lipid tail of LTC4, their critical and differential role in the transport of conjugated estrogens and anticancer drugs remains unexplained.—Conseil, G., Arama-Chayoth, M., Tsfadia, Y., Cole, S. P. C. Structure-guided probing of the leukotriene C4 binding site in human multidrug resistance protein 1 (MRP1; ABCC1). FA8EB J. 33, 10692–10704 (2019). www.fasebj.org.

Original languageEnglish
Pages (from-to)10692-10704
Number of pages13
JournalFASEB Journal
Volume33
Issue number10
DOIs
StatePublished - 1 Oct 2019

Keywords

  • ABC transporter
  • bipartite binding site
  • homology modeling
  • structure-function

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