Doxycycline has distinct apicoplast-specific mechanisms of antimalarial activity

  1. Megan Okada
  2. Ping Guo
  3. Shai-anne Nalder
  4. Paul A Sigala  Is a corresponding author
  1. University of Utah School of Medicine, United States

Abstract

Doxycycline (DOX) is a key antimalarial drug thought to kill Plasmodium parasites by blocking protein translation in the essential apicoplast organelle. Clinical use is primarily limited to prophylaxis due to delayed second-cycle parasite death at 1-3 µM serum concentrations. DOX concentrations >5 µM kill parasites with first-cycle activity but have been ascribed to off-target mechanisms outside the apicoplast. We report that 10 µM DOX blocks apicoplast biogenesis in the first cycle and is rescued by isopentenyl pyrophosphate, an essential apicoplast product, confirming an apicoplast-specific mechanism. Exogenous iron rescues parasites and apicoplast biogenesis from first- but not second-cycle effects of 10 µM DOX, revealing that first-cycle activity involves a metal-dependent mechanism distinct from the delayed-death mechanism. These results critically expand the paradigm for understanding the fundamental antiparasitic mechanisms of DOX and suggest repurposing DOX as a faster-acting antimalarial at higher dosing whose multiple mechanisms would be expected to limit parasite resistance.

Data availability

All data reported or described in this manuscript are available and included in the main and supplemental figures and in the microscopy source data file.

Article and author information

Author details

  1. Megan Okada

    Biochemistry, University of Utah School of Medicine, Salt Lake City, United States
    Competing interests
    The authors declare that no competing interests exist.
  2. Ping Guo

    Biochemistry, University of Utah School of Medicine, Salt Lake City, United States
    Competing interests
    The authors declare that no competing interests exist.
  3. Shai-anne Nalder

    Biochemistry, University of Utah School of Medicine, Salt Lake City, United States
    Competing interests
    The authors declare that no competing interests exist.
  4. Paul A Sigala

    Biochemistry, University of Utah School of Medicine, Salt Lake City, United States
    For correspondence
    p.sigala@biochem.utah.edu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-3464-3042

Funding

National Institute of Diabetes and Digestive and Kidney Diseases (T32DK007115)

  • Megan Okada

National Heart and Lung Institute (R25HL108828)

  • Shai-anne Nalder

National Institute of Diabetes and Digestive and Kidney Diseases (U54DK110858)

  • Paul A Sigala

Burroughs Wellcome Fund (1011969)

  • Paul A Sigala

Pew Charitable Trusts (32099)

  • Paul A Sigala

National Institute of General Medical Sciences (R35GM133764)

  • Paul A Sigala

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

Reviewing Editor

  1. Jon Clardy, Harvard Medical School, United States

Publication history

  1. Received: June 21, 2020
  2. Accepted: November 1, 2020
  3. Accepted Manuscript published: November 2, 2020 (version 1)
  4. Version of Record published: November 16, 2020 (version 2)

Copyright

© 2020, Okada 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. Megan Okada
  2. Ping Guo
  3. Shai-anne Nalder
  4. Paul A Sigala
(2020)
Doxycycline has distinct apicoplast-specific mechanisms of antimalarial activity
eLife 9:e60246.
https://doi.org/10.7554/eLife.60246

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