Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.08.07.241463v1?rss=1 Authors: Tassis, K., Vietrov, R., Koning, M. d., de Boer, M., Gouridis, G., Cordes, T. Abstract: The current model of active transport via ABC importers is mostly based on structural, biochemical and genetic data. We here establish single-molecule Foerster-resonance energy transfer (smFRET) assays to monitor the conformational states and heterogeneity of the type-I ABC importer OpuA from Lactococcus lactis. Our studies include intradomain assays that elucidate conformational changes within the substrate-binding domain (SBD) OpuAC and interdomain assays between SBDs or transmembrane domains. Using the methodology, we studied ligand-binding mechanisms as well as ATP and glycine betaine dependences of conformational changes. Our study expands the scope of smFRET investigations towards a class of so far unstudied ABC importers, and paves the way for a full understanding of their transport cycle in the future. Copy rights belong to original authors. Visit the link for more info