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Structure of the formate transporter FocA reveals a pentameric aquaporin-like channel

Nature volume 462, pages 467–472 (2009)Cite this article

Abstract

FocA is a representative member of the formate–nitrite transporter family, which transports short-chain acids in bacteria, archaea, fungi, algae and parasites. The structure and transport mechanism of the formate–nitrite transporter family remain unknown. Here we report the crystal structure of Escherichia coli FocA at 2.25 Å resolution. FocA forms a symmetric pentamer, with each protomer consisting of six transmembrane segments. Despite a lack of sequence homology, the overall structure of the FocA protomer closely resembles that of aquaporin and strongly argues that FocA is a channel, rather than a transporter. Structural analysis identifies potentially important channel residues, defines the channel path and reveals two constriction sites. Unlike aquaporin, FocA is impermeable to water but allows the passage of formate. A structural and biochemical investigation provides mechanistic insights into the channel activity of FocA.

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Figure 1: The overall structure of FocA.
Figure 2: Structural features of the FocA protomer.
Figure 3: The FocA protomer is structurally similar to aquaporin.
Figure 4: Features of the axial channel in the FocA protomer.
Figure 5: FocA contains two constriction sites and may exist in a closed-pore state.

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Accession codes

Primary accessions

Protein Data Bank

Data deposits

The atomic coordinates of FocA in the P212121 and P32 space groups have been deposited in the Protein Data Bank under accession codes 3KCU and 3KCV, respectively.

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Acknowledgements

We thank N. Shimizu, S. Baba and T. Kumasaka at the Spring-8 beamline BL41XU for assistance, and J. He and S. Huang for help at Shanghai Synchrotron Radiation Facility (SSRF). This work was supported by funds from the Ministry of Science and Technology of China (grants 2009CB918801 and 2009CB918802), Tsinghua University 985 Phase II funds, Project 30888001 supported by National Natural Science Foundation of China, and the Beijing Municipal Commissions of Education and Science and Technology. N.Y. acknowledges support from the Yuyuan Foundation and Li’s Foundation.

Author Contributions Experiments were performed by Y.W., Y.H., J.W., C.C., W.H., P.L., Y.-N.X., P.W. and N.Y. Data were analysed by Y.W., Y.H., J.W., N.Y. and Y.S. The manuscript was prepared by N.Y. and Y.S.

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Author notes

  1. Yi Wang, Yongjian Huang and Jiawei Wang: These authors contributed equally to this work.

Authors and Affiliations

  1. Ministry of Education Protein Science Laboratory,,

    Yi Wang, Peilong Lu & Yigong Shi

  2. State Key Laboratory of Biomembrane and Membrane Biotechnology, Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China ,

    Yongjian Huang, Jiawei Wang, Chao Cheng, Weijiao Huang & Nieng Yan

  3. Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China

    Ya-Nan Xu & Pengye Wang

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  1. Yi Wang
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Correspondence to Nieng Yan or Yigong Shi.

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Wang, Y., Huang, Y., Wang, J. et al. Structure of the formate transporter FocA reveals a pentameric aquaporin-like channel . Nature 462, 467–472 (2009). https://doi.org/10.1038/nature08610

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