Plasticity of the proteasome-targeting signal Fat10 enhances substrate degradation

  1. Hitendra Negi
  2. Aravind Ravichandran
  3. Pritha Dasgupta
  4. Shridivya Reddy
  5. Ranabir Das  Is a corresponding author
  1. Tata Institute of Fundamental Research, India

Abstract

The proteasome controls levels of most cellular proteins, and its activity is regulated under stress, quiescence, and inflammation. However, factors determining the proteasomal degradation rate remain poorly understood. Proteasome substrates are conjugated with small proteins (tags) like ubiquitin and Fat10 to target them to the proteasome. It is unclear if the structural plasticity of proteasome-targeting tags can influence substrate degradation. Fat10 is upregulated during inflammation, and its substrates undergo rapid proteasomal degradation. We report that the degradation rate of Fat10 substrates critically depends on the structural plasticity of Fat10. While the ubiquitin tag is recycled at the proteasome, Fat10 is degraded with the substrate. Our results suggest significantly lower thermodynamic stability and faster mechanical unfolding in Fat10 compared to ubiquitin. Long-range salt bridges are absent in the Fat10 structure, creating a plastic protein with partially unstructured regions suitable for proteasome engagement. Fat10 plasticity destabilizes substrates significantly and creates partially unstructured regions in the substrate to enhance degradation. NMR-relaxation-derived order parameters and temperature dependence of chemical shifts identify the Fat10-induced partially unstructured regions in the substrate, which correlated excellently to Fat10-substrate contacts, suggesting that the tag-substrate collision destabilizes the substrate. These results highlight a strong dependence of proteasomal degradation on the structural plasticity and thermodynamic properties of the proteasome-targeting tags.

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Author details

  1. Hitendra Negi

    National Center for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
    Competing interests
    The authors declare that no competing interests exist.
  2. Aravind Ravichandran

    National Center for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
    Competing interests
    The authors declare that no competing interests exist.
  3. Pritha Dasgupta

    National Center for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
    Competing interests
    The authors declare that no competing interests exist.
  4. Shridivya Reddy

    National Center for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
    Competing interests
    The authors declare that no competing interests exist.
  5. Ranabir Das

    National Center for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
    For correspondence
    rana@ncbs.res.in
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-5114-6817

Funding

Tata Institute of Fundamental Research (RTI4006)

  • Ranabir Das

Science and Engineering Research Board (CRG/2021/006032)

  • Ranabir Das

Department of Biotechnology, Ministry of Science and Technology, India (dbt/pr12422/med/31/287/2014)

  • Ranabir Das

Council of Scientific and Industrial Research, India

  • Hitendra Negi

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Copyright

© 2024, Negi et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

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  1. Hitendra Negi
  2. Aravind Ravichandran
  3. Pritha Dasgupta
  4. Shridivya Reddy
  5. Ranabir Das
(2024)
Plasticity of the proteasome-targeting signal Fat10 enhances substrate degradation
eLife 13:e91122.
https://doi.org/10.7554/eLife.91122

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https://doi.org/10.7554/eLife.91122