1. Cell Biology
  2. Genetics and Genomics

Unleashing a novel function of endonuclease G in mitochondrial genome instability

  1. Sumedha Dahal
  2. Humaira Siddiqua
  3. Shivangi Sharma
  4. Ravi K Babu
  5. Diksha Rathore
  6. Sheetal Sharma
  7. Sathees C Raghavan  Is a corresponding author
  1. Indian Institute of Science Bangalore, India
  2. Post Graduate Institute of Medical Education and Research, India
https://doi.org/10.7554/eLife.69916
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Cite this article
  1. Sumedha Dahal
  2. Humaira Siddiqua
  3. Shivangi Sharma
  4. Ravi K Babu
  5. Diksha Rathore
  6. Sheetal Sharma
  7. Sathees C Raghavan
(2022)
Unleashing a novel function of endonuclease G in mitochondrial genome instability
eLife 11:e69916.
https://doi.org/10.7554/eLife.69916
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Abstract

Having its genome makes the mitochondrion a unique and semiautonomous organelle within cells. Mammalian mitochondrial DNA (mtDNA) is a double-stranded closed circular molecule of about 16 kb coding for 37 genes. Mutations, including deletions in the mitochondrial genome, can culminate in different human diseases. Mapping the deletion junctions suggests that the breakpoints are generally seen at hotspots. '9-bp deletion' (8271-8281), seen in the intergenic region of cytochrome c oxidase II/tRNALys, is the most common mitochondrial deletion. While it is associated with several diseases like myopathy, dystonia, and hepatocellular carcinoma, it has also been used as an evolutionary marker. However, the mechanism responsible for its fragility is unclear. In the current study, we show that Endonuclease G, a mitochondrial nuclease responsible for nonspecific cleavage of nuclear DNA during apoptosis, can induce breaks at sequences associated with '9-bp deletion' when it is present on a plasmid or in the mitochondrial genome. Through a series of in vitro and intracellular studies, we show that Endonuclease G binds to G-quadruplex structures formed at the hotspot and induces DNA breaks. Therefore, we uncover a new role for Endonuclease G in generating mtDNA deletions, which depends on the formation of G4 DNA within the mitochondrial genome. In summary, we identify a novel property of Endonuclease G, besides its role in apoptosis and the recently described elimination of paternal mitochondria during fertilisation.

Data availability

All data generated or analysed during this study are included in the manuscript and supporting files. Source data for each data is provided along with the figures

Article and author information

Author details

  1. Sumedha Dahal

    Department of Biochemistry, Indian Institute of Science Bangalore, Bangalore, India
    Competing interests
    The authors declare that no competing interests exist.

  2. Humaira Siddiqua

    Department of Biochemistry, Indian Institute of Science Bangalore, Bangalore, India
    Competing interests
    The authors declare that no competing interests exist.

  3. Shivangi Sharma

    Department of Biochemistry, Indian Institute of Science Bangalore, Bangalore, India
    Competing interests
    The authors declare that no competing interests exist.

  4. Ravi K Babu

    Department of Biochemistry, Indian Institute of Science Bangalore, Bangalore, India
    Competing interests
    The authors declare that no competing interests exist.

  5. Diksha Rathore

    Department of Biochemistry, Indian Institute of Science Bangalore, Bangalore, India
    Competing interests
    The authors declare that no competing interests exist.

  6. Sheetal Sharma

    Department of Experimental Medicine, Post Graduate Institute of Medical Education and Research, Chandigarh, India
    Competing interests
    The authors declare that no competing interests exist.

  7. Sathees C Raghavan

    Department of Biochemistry, Indian Institute of Science Bangalore, Bangalore, India
    For correspondence
    sathees@iisc.ac.in
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-3003-1417

Funding

Council of Scientific and Industrial Research, India (37(1692)/17/EMR-11)

  • Sathees C Raghavan

Department of Atomic Energy, Government of India (21/01/2016-BRNS/35074)

  • Sathees C Raghavan

Department of Biotechnology, Ministry of Science and Technology, India (BT/PR/3458/COE/34/33/2015)

  • Sathees C Raghavan

IISc-DBT partnership programme (BT/PR27952-INF/22/212/2018)

  • Sathees C Raghavan

Indian Institute of Science

  • Sumedha Dahal

Indian Institute of Science

  • Humaira Siddiqua

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

Ethics

Animal experimentation: This study was performed in strict accordance with the recommendations in the Guide for the Care and Use of Laboratory Animals of the Indian National Law on animal care and use. All of the animals were handled according to approved institutional animal care and use committee protocols (CAF-SOP) of the Indian Institute of Science, Bangalore. The protocol was approved by the Committee on the Ethics of Animal Experiments of the Central Animal Facility (CAF/Ethics/526/2016).

Copyright

© 2022, Dahal 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. Sumedha Dahal
  2. Humaira Siddiqua
  3. Shivangi Sharma
  4. Ravi K Babu
  5. Diksha Rathore
  6. Sheetal Sharma
  7. Sathees C Raghavan
(2022)
Unleashing a novel function of endonuclease G in mitochondrial genome instability
eLife 11:e69916.
https://doi.org/10.7554/eLife.69916

Share this article

https://doi.org/10.7554/eLife.69916

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