Mapping the ATP Hydrolysis Cycle of a Clostridium Perfringens ABC Transporter

Abstract

ATP-Binding Cassette (ABC) transporters are a diverse class of integral membrane proteins that couple the hydrolysis of ATP to the transport of substrates across the lipid bilayer. Despite a steady stream of structures over the last few years, ABC transporters lack a description of their common mechanism of transport due to their structural and substrate diversity. In an attempt to capture an ABC transporter in multiple conformations throughout the ATP-hydrolysis cycle, we have reconstituted a heterodimeric Clostridium perfringens exporter into lipid nanodiscs. Using single particle cryo-electron microscopy (cryoEM), we have obtained high-resolution structures of CpeAB-nanodisc in a nucleotide-unbound state, an ATP-bound state, and are currently pursuing ADP-bound state. These structures will be snapshots of the enzyme along its cycle, and taken together with biochemical data, will provide a detailed description of its transport mechanism.