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Conformational dynamics in substrate-binding domains influences transport in the ABC importer GlnPQ

Gouridis, G., Schuurman-Wolters, G., Ploetz, E., Husada, F., Vietrov, R., de Boer, M., Cordes, T. & Poolman, B., Jan-2015, In : Nature Structural & Molecular Biology. 22, 1, p. 57-64 8 p.

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  • Conformational dynamics in substrate-binding domains influences transport

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DOI

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.

Original languageEnglish
Pages (from-to)57-64
Number of pages8
JournalNature Structural & Molecular Biology
Volume22
Issue number1
Publication statusPublished - Jan-2015

    Keywords

  • Amino Acid Transport Systems, Basic, Biological Transport, Fluorescence Resonance Energy Transfer, Lactococcus lactis, Models, Biological, Models, Molecular, Protein Binding, Protein Conformation
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