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Structure of a bacterial energy-coupling factor transporter

Nature volume 497, pages 272–276 (2013)Cite this article

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Abstract

The 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 transporters1,2,3. 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 Å. The T component has a horseshoe-shaped open architecture, with five α-helices as transmembrane segments and two cytoplasmic α-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.

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Figure 1: Overall structure of a quaternary ECF transporter.
Figure 2: The coupling between EcfT and EcfA–EcfA′.
Figure 3: Structural features of EcfS.
Figure 4: A working model for the ECF transporter.

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Accession codes

Accessions

Protein Data Bank

Data deposits

The atomic coordinates of the quaternary ECF transporter have been deposited in the Protein Data Bank under the accession code 4HZU.

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Acknowledgements

We thank S. Huang and J. He at SSRF beamline BL17U for on-site assistance. This work was supported by funds from the Ministry of Science and Technology (973 Programs 2009CB918801 and 2013CB910602) and the National Natural Science Foundation of China (31021002 and 31130002).

Author information

Author notes

  1. Tingliang Wang and Guobin Fu: These authors contributed equally to this work.

Authors and Affiliations

  1. Ministry of Education Key Laboratory of Protein Science, Tsinghua University, Beijing, 100084, China

    Tingliang Wang, Guobin Fu, Xiaojing Pan, Jianping Wu, Xinqi Gong & Yigong Shi

  2. Tsinghua-Peking Joint Center for Life Sciences, Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing, 100084, China

    Tingliang Wang, Guobin Fu, Xiaojing Pan, Jianping Wu, Xinqi Gong & Yigong Shi

  3. State Key Laboratory of Bio-membrane and Membrane Biotechnology, Tsinghua University, Beijing, 100084, China

    Jiawei Wang

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Contributions

T.W., G.F., X.G. and Y.S. designed all experiments. T.W., G.F., X.P., J. Wu, X.G. and J. Wa. performed the experiments. All authors contributed to data analysis. T.W., G.F., X.G., J. Wa. and Y.S. contributed to manuscript preparation. Y.S. wrote the manuscript.

Corresponding author

Correspondence to Yigong Shi.

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The authors declare no competing financial interests.

Supplementary information

Supplementary Information

This file contains Supplementary Table 1, Supplementary Figures 1-12 Supplementary References. (PDF 4106 kb)

Suggested directionality of ECF motion

This animation shows the simulated motion of ECF and gives a sense of the direction of movement by the ECF transporter. (MPG 3969 kb)

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Wang, T., Fu, G., Pan, X. et al. Structure of a bacterial energy-coupling factor transporter. Nature 497, 272–276 (2013). https://doi.org/10.1038/nature12045

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