The ABCG2 multidrug transporter is a pump gated by a valve and an extracellular lid

• Published in: Nature communications 2019-11, Vol.10 (1), p.5433-14, Article 5433
• Main Authors: Khunweeraphong, Narakorn, Szöllősi, Daniel, Stockner, Thomas, Kuchler, Karl
• Format: Article
• Language: English
• Subjects: 13; 13/1; 13/109; 13/31; 13/44; 14; 14/19; 38; 38/109; 38/22; 38/23; 38/70; 38/77; 42; 631/1647; 631/45; 631/57; 631/67; 631/80; Antineoplastic Agents - metabolism; ATP Binding Cassette Transporter, Subfamily G, Member 2 - genetics; ATP Binding Cassette Transporter, Subfamily G, Member 2 - metabolism; ATP Binding Cassette Transporter, Subfamily G, Member 2 - ultrastructure; Detoxification; Drug delivery systems; Drug Resistance, Neoplasm - genetics; Extrusion; HEK293 Cells; Holes; Humanities and Social Sciences; Humans; Hydrophobicity; Leucine; Mitoxantrone - metabolism; Molecular Docking Simulation; multidisciplinary; Mutagenesis, Site-Directed; Mutation; Neoplasm Proteins - genetics; Neoplasm Proteins - metabolism; Neoplasm Proteins - ultrastructure; Physiology; Proteins; Residues; Roofs; Science; Science (multidisciplinary); Substrates; Translocation
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-019-13302-2

The human ATP-binding cassette transporter ABCG2 is a key to anticancer resistance and physiological detoxification. However, the molecular mechanism of substrate transport remains enigmatic. A hydrophobic di-leucine motif in the ABCG2 core separates a large intracellular cavity from a smaller upper cavity. We show that the di-leucine motif acts as a valve that controls drug extrusion. Moreover, the extracellular structure engages the re-entry helix and all extracellular loops to form a roof architecture on top of the upper cavity. Disulfide bridges and a salt bridge limit roof flexibility, but provide a lid-like function to control drug release. We propose that drug translocation from the central to the upper cavities through the valve is driven by a squeezing motion, suggesting that ABCG2 operates similar to a peristaltic pump. Finally, the roof contains essential residues, offering therapeutic options to block ABCG2 by either targeting the valve or essential residues in the roof. The human ATP-binding cassette transporter ABCG2 plays critical roles in anticancer resistance but the molecular mechanism of ABCG2-mediated substrate transport remains enigmatic. Here authors use extensive mutagenesis and molecular dynamics simulations to reveal a mechanistic basis for the function of the di-leucine valve and the roof organization in the transport cycle.