title: Energy coupling factor-type ABC transporters for vitamin uptake in prokaryotes.
abstract: Energy coupling factor (ECF) transporters are a subgroup of ATP-binding cassette (ABC) transporters involved in the uptake of vitamins and micronutrients in prokaryotes. In contrast to classical ABC importers, ECF transporters do not make use of water-soluble substrate binding proteins or domains but instead employ integral membrane proteins for substrate binding (named S-components). S-components form active translocation complexes with the ECF module, an assembly of two nucleotide-binding domains (NBDs, or EcfA) and a second transmembrane protein. In some cases, the ECF module is dedicated to a single S-component, but in many cases, the ECF module can interact with several different S-components that are unrelated in sequence and bind diverse substrates. The modular organization with exchangeable S-components on a single ECF module allows the transport of chemically different substrates via a common route. The recent determination of the crystal structures of the S-components that recognize thiamin and riboflavin has provided a first clue about the mechanism of S-component exchange. This review describes recent advances and the current views of the mechanism of transport by ECF transporters.
authors.affiliation: University of Groningen, Department of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
authors.forename: Guus B
authors.initials: GB
authors.lastname: Erkens
authors.forename: Maria
authors.initials: M
authors.lastname: Majsnerowska
authors.forename: Josy
authors.initials: J
authors.lastname: ter Beek
authors.forename: Dirk Jan
authors.initials: DJ
authors.lastname: Slotboom
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000737:chemistry* / Q000378:metabolism*; D001419:Bacteria / Q000737:chemistry / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D011487:Protein Conformation; D014815:Vitamins / Q000378:metabolism*
chemical_list: D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D014815:Vitamins