Single-molecule visualization of conformational changes and substrate transport in the vitamin B₁₂ ABC importer BtuCD-F.

ABSTRACT: ATP-binding cassette (ABC) transporters form the largest class of active membrane transport proteins. Binding and hydrolysis of ATP by their highly conserved nucleotide-binding domains drive conformational changes of the complex that mediate transport of substrate across the membrane. The vitamin B₁₂ importer BtuCD-F in Escherichia coli is an extensively studied model system. The periplasmic soluble binding protein BtuF binds the ligand; the transmembrane and ATPase domains BtuCD mediate translocation. Here we report the direct observation at the single-molecule level of ATP, vitamin B₁₂ and BtuF-induced events in the transporter complex embedded in liposomes. Single-molecule fluorescence imaging techniques reveal that membrane-embedded BtuCD forms a stable complex wi

SUBMITTER: Goudsmits JMH 

PROVIDER: S-EPMC5698293 | biostudies-literature | 2017 Nov

REPOSITORIES: biostudies-literature