title: ATP binding drives substrate capture in an ECF transporter by a release-and-catch mechanism.
abstract: ECF transporters are a family of active transporters for vitamins. They are composed of four subunits: a membrane-embedded substrate-binding subunit (EcfS), a transmembrane coupling subunit (EcfT) and two ATP-binding-cassette ATPases (EcfA and EcfA'). We have investigated the mechanism of the ECF transporter for riboflavin from the pathogen Listeria monocytogenes, LmECF-RibU. Using structural and biochemical approaches, we found that ATP binding to the EcfAA' ATPases drives a conformational change that dissociates the S subunit from the EcfAA'T ECF module. Upon release from the ECF module, the RibU S subunit then binds the riboflavin transport substrate. We also find that S subunits for distinct substrates compete for the ATP-bound state of the ECF module. Our results explain how ECF transporters capture the transport substrate and reproduce the in vivo observations on S-subunit competition for which the family was named.
authors.affiliation: Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, New York, USA.
authors.forename: Nathan K
authors.initials: NK
authors.lastname: Karpowich
authors.affiliation: Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, New York, USA.
authors.forename: Jin Mei
authors.initials: JM
authors.lastname: Song
authors.affiliation: Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, New York, USA.
authors.forename: Nicolette
authors.initials: N
authors.lastname: Cocco
authors.affiliation: Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, New York, USA.
authors.forename: Da-Neng
authors.initials: DN
authors.lastname: Wang
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D018360:Crystallography, X-Ray; D006801:Humans; D008089:Listeria monocytogenes / Q000737:chemistry / Q000378:metabolism*; D008088:Listeriosis / Q000382:microbiology; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D011487:Protein Conformation; D055503:Protein Multimerization; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism; D012256:Riboflavin / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D026901:Membrane Transport Proteins; D021122:Protein Subunits; D000255:Adenosine Triphosphate; D012256:Riboflavin