Conformational and dynamical plasticity in substrate-binding proteins underlies selective transport in ABC importers
- University of Groningen, Netherlands
- KU Leuven, Belgium
- University of Melbourne, Australia
- Ludwig Maximilians-Universität München, Germany
Abstract
Substrate-binding proteins (SBPs) are associated with ATP-binding cassette importers and switch from an open to a closed conformation upon substrate binding, providing specificity for transport. We investigated the effect of substrates on the conformational dynamics of six SBPs and the impact on transport. Using single-molecule FRET, we reveal an unrecognized diversity of plasticity in SBPs. We show that a unique closed SBP conformation does not exist for transported substrates. Instead, SBPs sample a range of conformations that activate transport. Certain non-transported ligands leave the structure largely unaltered or trigger a conformation distinct from that of transported substrates. Intriguingly, in some cases similar SBP conformations are formed by both transported and non-transported ligands. In this case, the inability for transport arises from slow opening of the SBP or the selectivity provided by the translocator. Our results reveal the complex interplay between ligand-SBP interactions, SBP conformational dynamics and substrate transport.
Data availability
Data generated or analysed during this study are included in the manuscript and supporting files. Source data files are available for smFRET histogrammes, representative smFRET time-traces and smFRET dwell-time histogrammes as shown in the manuscript. Primer sequences for created protein mutants are included.
Article and author information
Author details
Christopher A McDevitt
Funding
European Commission (638536)
- Thorben Cordes
European Molecular Biology Organization (ALF 47-2012)
- Giorgos Gkouridis
Deutsche Forschungsgemeinschaft (GRK2062/1 (C03))
- Thorben Cordes
Deutsche Forschungsgemeinschaft (SFB863 (A13))
- Thorben Cordes
National Health and Medical Research Council (1080784)
- Christopher A McDevitt
National Health and Medical Research Council (1122582)
- Christopher A McDevitt
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (722.012.012)
- Giorgos Gkouridis
European Commission (670578)
- Bert Poolman
Australian Research Council (DP170102102)
- Christopher A McDevitt
Australian Research Council (FT170100006)
- Christopher A McDevitt
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2019, de Boer et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Conformational and dynamical plasticity in substrate-binding proteins underlies selective transport in ABC importers
eLife 8:e44652.
https://doi.org/10.7554/eLife.44652
