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Structure and mechanism of the hexameric MecA–ClpC molecular machine

Nature volume 471, pages 331335 (17 March 2011) | Download Citation

Abstract

Regulated proteolysis by ATP-dependent proteases is universal in all living cells. Bacterial ClpC, a member of the Clp/Hsp100 family of AAA+ proteins (ATPases associated with diverse cellular activities) with two nucleotide-binding domains (D1 and D2), requires the adaptor protein MecA for activation and substrate targeting. The activated, hexameric MecA–ClpC molecular machine harnesses the energy of ATP binding and hydrolysis to unfold specific substrate proteins and translocate the unfolded polypeptide to the ClpP protease for degradation. Here we report three related crystal structures: a heterodimer between MecA and the amino domain of ClpC, a heterododecamer between MecA and D2-deleted ClpC, and a hexameric complex between MecA and full-length ClpC. In conjunction with biochemical analyses, these structures reveal the organizational principles behind the hexameric MecA–ClpC complex, explain the molecular mechanisms for MecA-mediated ClpC activation and provide mechanistic insights into the function of the MecA–ClpC molecular machine. These findings have implications for related Clp/Hsp100 molecular machines.

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Data deposits

The atomic coordinates and structure factors of the ClpC N domain, the MecA121–ClpC N-domain complex, the hexameric complex of MecA121–ClpC-ΔD2 and the hexameric complex of MecA108–ClpC have been deposited in the Protein Data Bank with the accession codes 2Y1Q, 2Y1R, 3PXG and 3PXI, respectively.

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Acknowledgements

We thank J. He and S. Huang at Shanghai Synchrotron Radiation Source and staff at the SPring-8 beamline BL41XU for help. This work was supported by Project 30888001 of the National Natural Science Foundation of China (Y.S.) and Postdoctoral Fellowship #023201058 from the China Postdoctoral Science Foundation (Z.M.).

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Author notes

    • Feng Wang
    •  & Ziqing Mei

    These authors contributed equally to this work.

Affiliations

  1. Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China

    • Feng Wang
    • , Ziqing Mei
    • , Yutao Qi
    • , Chuangye Yan
    • , Qi Hu
    • , Jiawei Wang
    •  & Yigong Shi

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Contributions

F.W., Z.M., and Y.S. designed all experiments. F.W., Z.M., Y.Q., C.Y., Q.H., and J.W. performed the experiments. All authors analysed the data. F.W., Z.M., J.W. and Y.S. contributed to manuscript preparation. Y.S. wrote the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Jiawei Wang or Yigong Shi.

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    Supplementary Information

    The file contains Supplementary Tables 1-2 and Supplementary Figures 1-11 with legends.

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https://doi.org/10.1038/nature09780

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