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.

中文翻译：

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ABC进口商OpuA中的构象状态和动力学的单分子研究

当前通过ABC进口商进行主动运输的模型主要基于结构，生化和遗传数据。我们在这里建立单分子Foerster共振能量转移（smFRET）分析法，以监测来自乳酸乳球菌的I型ABC进口商OpuA的构象状态和异质性。我们的研究包括阐明底物结合域（SBD）OpuAC内构象变化的域内测定，以及SBD或跨膜结构域之间的域间测定。使用该方法，我们研究了配体结合机制以及构象变化的ATP和甘氨酸甜菜碱依赖性。我们的研究将smFRET研究的范围扩大到一类到目前为止尚未研究的ABC进口商，并为全面了解其未来的运输周期铺平了道路。