Molecular basis of cholesterol efflux via ABCG subfamily transporters

Yingyuan Sun, Jin Wang, Tao Long, Xiaofeng Qi, Linda Donnelly, Nadia Elghobashi-Meinhardt, Leticia Esparza, Jonathan C. Cohen, Xiao Song Xie, Helen H. Hobbs, Xiaochun Li

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

The ABCG1 homodimer (G1) and ABCG5–ABCG8 heterodimer (G5G8), two members of the adenosine triphosphate (ATP)–binding cassette (ABC) transporter G family, are required for maintenance of cellular cholesterol levels. G5G8 mediates secretion of neutral sterols into bile and the gut lumen, whereas G1 transports cholesterol from macrophages to high-density lipoproteins (HDLs). The mechanisms used by G5G8 and G1 to recognize and export sterols remain unclear. Here, we report cryoelectron microscopy (cryo-EM) structures of human G5G8 in sterol-bound and human G1 in cholesterol- and ATP-bound states. Both transporters have a sterol-binding site that is accessible from the cytosolic leaflet. A second site is present midway through the transmembrane domains of G5G8. The Walker A motif of G8 adopts a unique conformation that accounts for the marked asymmetry in ATPase activities between the two nucleotide-binding sites of G5G8. These structures, along with functional validation studies, provide a mechanistic framework for understanding cholesterol efflux via ABC transporters.

Original languageEnglish (US)
Article numbere2110483118
JournalProceedings of the National Academy of Sciences of the United States of America
Volume118
Issue number34
DOIs
StatePublished - Aug 24 2021

Keywords

  • ABCG1
  • ABCG5
  • ABCG8
  • Plant sterol
  • Sitosterolemia

ASJC Scopus subject areas

  • General

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