Cholesterol sensing by the ABCG1 lipid transporter: Requirement of a CRAC motif in the final transmembrane domain.
The ATP-binding cassette (ABC) transporter, ABCG1, is a lipid exporter involved in removal of cholesterol from cells that has been investigated for its role in foam cells formation and atherosclerosis. The mechanism by which ABC lipid transporters bind and recognise their substrates is currently unknown. In this study, we identify a critical region in the final transmembrane domain of ABCG1, which is essential for its export function and stabilisation by cholesterol, a post-translational regulatory mechanism that we have recently identified as dependent on protein ubiquitination. This transmembrane region contains several Cholesterol Recognition/interaction Amino acid Consensus (CRAC) motifs, and its inverse CARC motifs. Mutational analyses identify one CRAC motif in particular with Y667 at its core, that is especially important for transport activity to HDL as well as stability of the protein in the presence of cholesterol. In addition, we present a model of how cholesterol docks to this CRAC motif in an energetically favourable manner. This study identifies for the first time how ABCG1 can interact with cholesterol via a functional CRAC domain, which provides the first insight into the substrate-transporter interaction of an ABC lipid exporter.
Faculty of Pharmacy, The University of Sydney, Sydney NSW 2006, Australia; School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW 2052, Australia.
Laura J
LJ
Sharpe
Faculty of Pharmacy, The University of Sydney, Sydney NSW 2006, Australia.
Geetha
G
Rao
School of Medical and Molecular Biosciences, University of Technology Sydney, Sydney NSW 2007, Australia.
Peter M
PM
Jones
Faculty of Pharmacy, The University of Sydney, Sydney NSW 2006, Australia.
Elizabeth
E
Glancey
Faculty of Pharmacy, The University of Sydney, Sydney NSW 2006, Australia.
Shereen M
SM
Aleidi
School of Medical and Molecular Biosciences, University of Technology Sydney, Sydney NSW 2007, Australia.
Anthony M
AM
George
School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW 2052, Australia.
Andrew J
AJ
Brown
Faculty of Pharmacy, The University of Sydney, Sydney NSW 2006, Australia. Electronic address: ingrid.gelissen@sydney.edu.au.
Ingrid C
IC
Gelissen
D000070998:ATP Binding Cassette Transporter, Subfamily G, Member 1; D018528:ATP-Binding Cassette Transporters / Q000737:chemistry* / Q000502:physiology*; D000595:Amino Acid Sequence; D000818:Animals; D001692:Biological Transport / Q000235:genetics; D016466:CHO Cells; D002462:Cell Membrane / Q000378:metabolism; D002784:Cholesterol / Q000378:metabolism*; D006224:Cricetinae; D003412:Cricetulus; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding / Q000235:genetics; D054730:Protein Interaction Domains and Motifs / Q000235:genetics; D017433:Protein Structure, Secondary
C419353:ABCG1 protein, human; D000070998:ATP Binding Cassette Transporter, Subfamily G, Member 1; D018528:ATP-Binding Cassette Transporters; D002784:Cholesterol
ABCG1; CRAC motifs; Cholesterol binding domains; Cholesterol transport