title: Conformational dynamics in substrate-binding domains influences transport in the ABC importer GlnPQ.
abstract: The conformational dynamics in ABC transporters is largely elusive. The ABC importer GlnPQ from Lactococcus lactis has different covalently linked substrate-binding domains (SBDs), thus making it an excellent model system to elucidate the dynamics and role of the SBDs in transport. We demonstrate by single-molecule spectroscopy that the two SBDs intrinsically transit from open to closed ligand-free conformation, and the proteins capture their amino acid ligands via an induced-fit mechanism. High-affinity ligands elicit transitions without changing the closed-state lifetime, whereas low-affinity ligands dramatically shorten it. We show that SBDs in the closed state compete for docking onto the translocator, but remarkably the effect is strongest without ligand. We find that the rate-determining steps depend on the SBD and the amino acid transported. We conclude that the lifetime of the closed conformation controls both SBD docking to the translocator and substrate release.
authors.affiliation: 1] Department of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, the Netherlands. [2] Molecular Microscopy Research Group, Zernike Institute for Advanced Materials, University of Groningen, Groningen, the Netherlands.
authors.forename: Giorgos
authors.initials: G
authors.lastname: Gouridis
authors.affiliation: Department of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, the Netherlands.
authors.forename: Gea K
authors.initials: GK
authors.lastname: Schuurman-Wolters
authors.affiliation: Molecular Microscopy Research Group, Zernike Institute for Advanced Materials, University of Groningen, Groningen, the Netherlands.
authors.forename: Evelyn
authors.initials: E
authors.lastname: Ploetz
authors.affiliation: Molecular Microscopy Research Group, Zernike Institute for Advanced Materials, University of Groningen, Groningen, the Netherlands.
authors.forename: Florence
authors.initials: F
authors.lastname: Husada
authors.affiliation: Department of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, the Netherlands.
authors.forename: Ruslan
authors.initials: R
authors.lastname: Vietrov
authors.affiliation: 1] Department of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, the Netherlands. [2] Molecular Microscopy Research Group, Zernike Institute for Advanced Materials, University of Groningen, Groningen, the Netherlands.
authors.forename: Marijn
authors.initials: M
authors.lastname: de Boer
authors.affiliation: Molecular Microscopy Research Group, Zernike Institute for Advanced Materials, University of Groningen, Groningen, the Netherlands.
authors.forename: Thorben
authors.initials: T
authors.lastname: Cordes
authors.affiliation: Department of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, the Netherlands.
authors.forename: Bert
authors.initials: B
authors.lastname: Poolman
mesh_terms: D026923:Amino Acid Transport Systems, Basic / Q000737:chemistry* / Q000378:metabolism*; D001692:Biological Transport; D031541:Fluorescence Resonance Energy Transfer; D013294:Lactococcus lactis / Q000737:chemistry / Q000201:enzymology* / Q000378:metabolism; D008954:Models, Biological; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation
chemical_list: D026923:Amino Acid Transport Systems, Basic