title: Structure of MsbA from E. coli: a homolog of the multidrug resistance ATP binding cassette (ABC) transporters.
abstract: Multidrug resistance (MDR) is a serious medical problem and presents a major challenge to the treatment of disease and the development of novel therapeutics. ABC transporters that are associated with multidrug resistance (MDR-ABC transporters) translocate hydrophobic drugs and lipids from the inner to the outer leaflet of the cell membrane. To better elucidate the structural basis for the "flip-flop" mechanism of substrate movement across the lipid bilayer, we have determined the structure of the lipid flippase MsbA from Escherichia coli by x-ray crystallography to a resolution of 4.5 angstroms. MsbA is organized as a homodimer with each subunit containing six transmembrane alpha-helices and a nucleotide-binding domain. The asymmetric distribution of charged residues lining a central chamber suggests a general mechanism for the translocation of substrate by MsbA and other MDR-ABC transporters. The structure of MsbA can serve as a model for the MDR-ABC transporters that confer multidrug resistance to cancer cells and infectious microorganisms.
authors.affiliation: Department of Molecular Biology, MB-9, The Scripps Research Institute, La Jolla, CA 92037, USA. gchang@scripps.edu
authors.forename: G
authors.initials: G
authors.lastname: Chang
authors.forename: C B
authors.initials: CB
authors.lastname: Roth
mesh_terms: D018528:ATP-Binding Cassette Transporters; D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D001692:Biological Transport; D018360:Crystallography, X-Ray; D019281:Dimerization; D004352:Drug Resistance, Microbial; D018432:Drug Resistance, Multiple; D004926:Escherichia coli / Q000201:enzymology*; D008050:Lipid A / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D055672:Static Electricity; D013329:Structure-Activity Relationship
chemical_list: D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D008050:Lipid A; D008565:Membrane Proteins; C079726:MsbA protein, Bacteria; D000255:Adenosine Triphosphate