title: Membrane topology of ABC-type macrolide antibiotic exporter MacB in Escherichia coli.
abstract: MacB is an ABC-type membrane protein that exports only macrolide compounds containing 14- and 15-membered lactones, cooperating with a membrane fusion protein, MacA, and a multifunctional outer membrane channel, TolC. We determined the membrane topology of MacB by means of site-specific competitive chemical modification of single cysteine mutants. As a result, it was revealed that MacB is composed of four transmembrane (TM) segments with a cytoplasmic N-terminal nucleotide binding domain of about 270 amino acid residues and a periplasmic large hydrophilic polypeptide between TM segments 1 and 2 of about 200 amino acid residues.
authors.affiliation: Department of Cell Membrane Biology, Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan.
authors.forename: Nobuyoshi
authors.initials: N
authors.lastname: Kobayashi
authors.forename: Kunihiko
authors.initials: K
authors.lastname: Nishino
authors.forename: Takahiro
authors.initials: T
authors.lastname: Hirata
authors.forename: Akihito
authors.initials: A
authors.lastname: Yamaguchi
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D002250:Carbon Radioisotopes; D002462:Cell Membrane / Q000737:chemistry; D004926:Escherichia coli / Q000737:chemistry* / Q000235:genetics; D029968:Escherichia coli Proteins; D005033:Ethylmaleimide / Q000378:metabolism; D008969:Molecular Sequence Data; D011869:Radioligand Assay
chemical_list: D018528:ATP-Binding Cassette Transporters; D002250:Carbon Radioisotopes; D029968:Escherichia coli Proteins; C436313:MacB protein, E coli; D005033:Ethylmaleimide