DegP primarily functions as a protease for the biogenesis of β-barrel outer membrane proteins in the Gram-negative bacterium Escherichia coli

Authors

  • Xi Ge,

    1. State Key Laboratory of Protein and Plant Gene Research and School of Life Sciences, Peking University, China
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    • These authors contributed equally to this work
  • Rui Wang,

    1. State Key Laboratory of Protein and Plant Gene Research and School of Life Sciences, Peking University, China
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    • These authors contributed equally to this work
  • Jing Ma,

    1. State Key Laboratory of Protein and Plant Gene Research and School of Life Sciences, Peking University, China
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  • Yang Liu,

    1. State Key Laboratory of Protein and Plant Gene Research and School of Life Sciences, Peking University, China
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  • Anastasia N. Ezemaduka,

    1. State Key Laboratory of Protein and Plant Gene Research and School of Life Sciences, Peking University, China
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  • Peng R. Chen,

    1. Center for Protein Science, Peking University, China
    2. Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, China
    3. Peking-Tsinghua Center for Life Sciences, Beijing, China
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  • Xinmiao Fu,

    Corresponding author
    1. State Key Laboratory of Protein and Plant Gene Research and School of Life Sciences, Peking University, China
    2. Center for Protein Science, Peking University, China
    • Correspondence

      Z. Chang, State Key Laboratory of Protein and Plant Gene Research and School of Life Sciences, Peking University, Beijing 100871, China

      Fax: +86-10-62751526

      Tel: +86-10-62758822

      E-mail: changzy@pku.edu.cn

      X. Fu, State Key Laboratory of Protein and Plant Gene Research and School of Life Sciences, Peking University, Beijing 100871, China

      Fax: +86-10-62751526

      Tel: +86-10-62758056

      E-mail: fuxinmiao@pku.edu.cn

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  • Zengyi Chang

    Corresponding author
    1. State Key Laboratory of Protein and Plant Gene Research and School of Life Sciences, Peking University, China
    2. Center for Protein Science, Peking University, China
    3. Center for the History and Philosophy of Science, Peking University, China
    • Correspondence

      Z. Chang, State Key Laboratory of Protein and Plant Gene Research and School of Life Sciences, Peking University, Beijing 100871, China

      Fax: +86-10-62751526

      Tel: +86-10-62758822

      E-mail: changzy@pku.edu.cn

      X. Fu, State Key Laboratory of Protein and Plant Gene Research and School of Life Sciences, Peking University, Beijing 100871, China

      Fax: +86-10-62751526

      Tel: +86-10-62758056

      E-mail: fuxinmiao@pku.edu.cn

    Search for more papers by this author

Abstract

DegP (also designated as HtrA) and its homologs are found in prokaryotic cells and such eukaryotic organelles as mitochondria and chloroplasts. DegP has been found to be essential for the growth of Gram-negative bacteria under heat shock conditions and arguably considered to possess both protease and chaperone activities. The function of DegP has not been clearly defined. Using genetically incorporated non-natural amino acids as photo-crosslinkers, here we identified the β-barrel outer membrane proteins (OMPs) as the major natural substrates of DegP in Escherichia coli cells. We also demonstrated that DegP primarily functions as a protease, at both low and high temperatures, to eliminate unfolded OMPs, with hardly any appreciable chaperone activity in cells. We also found that the toxic and cell membrane-damaging misfolded OMPs would accumulate in DegP-lacking cells cultured under heat shock conditions. Together, our study defines the primary function of DegP in OMP biogenesis and offers a mechanistic insight into the essentiality of DegP for cell growth under heat shock conditions.

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