Research Data Supporting "ATP-dependent substrate transport by the ABC transporter MsbA is proton-coupled"

ATP-binding cassette transporters mediate the transbilayer movement of a vast number of substrates in or out of cells in organisms ranging from bacteria to humans. Current alternating access models for ABC exporters including the multidrug and Lipid A transporter MsbA from Escherichia coli suggest a role for nucleotide as the fundamental source of free energy. These models involve cycling between conformations with inward- and outward-facing substrate binding sites in response to engagement and hydrolysis of ATP at the nucleotide-binding domains. Here, we report that MsbA also utilizes another major energy currency in the cell by coupling substrate transport to a transmembrane electrochemical proton gradient. The dependence of ATP-dependent transport on proton coupling, and the stimulation of MsbA-ATPase by the chemical proton gradient highlight the functional integration of both forms of metabolic energy in MsbA-mediated transport. These findings introduce ion coupling as a new parameter in the mechanism of this homodimeric ABC transporter. The data for this publication have been uploaded in the Data Repository, and are numbered in accordance with the numbering of the figures in the Nature Communications publication.BBSRC (BB/I002383/1) BBSRC (BB/C004663/1) MRC (G0401165