Structural and mechanistic insights into prokaryotic energy-coupling factor transporters

Energy-coupling factor (ECF) transporters belong to the ATP-binding cassette (ABC)-transporter family and mediate the uptake of essential micronutrients in many prokaryotic species. Two crystal structures of bacterial ECF transporters have recently been obtained and suggest that transport involves an unprecedented re‑orientation of a membrane protein in the lipid bilayer during catalysis. In this Progress article, I present the new structural insights, discuss a testable model for the transport mechanism and consider the more general implications of these findings for our understanding of membrane transporters.