Structural highlights
FunctionECFA2_LEVBA ATP-binding (A) component of a common energy-coupling factor (ECF) ABC-transporter complex. Unlike classic ABC transporters this ECF transporter provides the energy necessary to transport a number of different substrates.[HAMAP-Rule:MF_01710] Publication Abstract from PubMedThe energy-coupling factor (ECF) transporters constitute a novel family of conserved membrane transporters in prokaryotes that have a similar domain organization to the ATP-binding cassette transporters. Each ECF transporter comprises a pair of cytosolic ATPases (the A and A' components, or EcfA and EcfA'), a membrane-embedded substrate-binding protein (the S component, or EcfS) and a transmembrane energy-coupling component (the T component, or EcfT) that links the EcfA-EcfA' subcomplex to EcfS. The structure and transport mechanism of the quaternary ECF transporter remain largely unknown. Here we report the crystal structure of a nucleotide-free ECF transporter from Lactobacillus brevis at a resolution of 3.5 A. The T component has a horseshoe-shaped open architecture, with five alpha-helices as transmembrane segments and two cytoplasmic alpha-helices as coupling modules connecting to the A and A' components. Strikingly, the S component, thought to be specific for hydroxymethyl pyrimidine, lies horizontally along the lipid membrane and is bound exclusively by the five transmembrane segments and the two cytoplasmic helices of the T component. These structural features suggest a plausible working model for the transport cycle of the ECF transporters. Structure of a bacterial energy-coupling factor transporter.,Wang T, Fu G, Pan X, Wu J, Gong X, Wang J, Shi Y Nature. 2013 May 9;497(7448):272-6. doi: 10.1038/nature12045. Epub 2013 Apr 14. PMID:23584587[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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