Letter

The essential mycobacterial amidotransferase GatCAB is a modulator of specific translational fidelity

  • Nature Microbiology 1, Article number: 16147 (2016)
  • doi:10.1038/nmicrobiol.2016.147
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Abstract

Although regulation of translation fidelity is an essential process1,​2,​3,​4,​5,​6,​7, diverse organisms and organelles have differing requirements of translational accuracy8,​9,​10,​11,​12,​13,​14,​15, and errors in gene translation serve an adaptive function under certain conditions16,​17,​18,​19,​20. Therefore, optimal levels of fidelity may vary according to context. Most bacteria utilize a two-step pathway for the specific synthesis of aminoacylated glutamine and/or asparagine tRNAs, involving the glutamine amidotransferase GatCAB21,​22,​23,​24,​25, but it had not been appreciated that GatCAB may play a role in modulating mistranslation rates. Here, by using a forward genetic screen, we show that the mycobacterial GatCAB enzyme complex mediates the translational fidelity of glutamine and asparagine codons. We identify mutations in gatA that cause partial loss of function in the holoenzyme, with a consequent increase in rates of mistranslation. By monitoring single-cell transcription dynamics, we demonstrate that reduced gatCAB expression leads to increased mistranslation rates, which result in enhanced rifampicin-specific phenotypic resistance. Consistent with this, strains with mutations in gatA from clinical isolates of Mycobacterium tuberculosis show increased mistranslation, with associated antibiotic tolerance, suggesting a role for mistranslation as an adaptive strategy in tuberculosis. Together, our findings demonstrate a potential role for the indirect tRNA aminoacylation pathway in regulating translational fidelity and adaptive mistranslation.

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Acknowledgements

This work was funded in part by the Bill and Melinda Gates Foundation (OPP1109789) and start-up funds from Tsinghua University to B.J. B.J. and T.F.Z. are Tsinghua-Janssen scholars. The authors thank S. Fortune, E. Rubin, M. Chao and P. Lehner for their critical reading of the manuscript, and C. Koser and P. Abel Zur Wiesch for helpful discussions. The authors also acknowledge technical assistance from the microbial sorting facility at Peking University, and thank the Clinical Database and Sample Bank of Tuberculosis of Beijing (D131100005313012) of the National Clinical Lab on Tuberculosis, Beijing Chest Hospital, for access to their strain collection.

Author information

Author notes

    • Hong-Wei Su
    •  & Jun-Hao Zhu

    These authors contributed equally to this work.

Affiliations

  1. Collaboration Innovation Centre for the Diagnosis and Treatment of Infectious Diseases, School of Medicine, Tsinghua University, Beijing 100084, China

    • Hong-Wei Su
    • , Jun-Hao Zhu
    • , Hao Li
    • , Rong-Jun Cai
    • , Xun Wang
    • , Yu-Xiang Chen
    •  & Babak Javid
  2. School of Life Sciences, Peking University, Beijing 10087, China

    • Jun-Hao Zhu
  3. Faculty of Health Sciences, DST/NRF Centre of Excellence for Biomedical TB Research, University of the Witwatersrand, National Health Laboratory Service, Johannesburg 2193, South Africa

    • Christopher Ealand
    •  & Bavesh D. Kana
  4. Center for Synthetic and Systems Biology, MOE Key Laboratory of Bioinformatics, Collaboration Innovation Centre for the Diagnosis and Treatment of Infectious Diseases, School of Life Sciences, Tsinghua University, Beijing 100084, China

    • Masood ur Rehman Kayani
    •  & Ting F. Zhu
  5. Wellcome Trust Sanger Institute, Hinxton CB10 1SA, UK

    • Danesh Moradigaravand
  6. National Clinical Laboratory on Tuberculosis, Beijing Tuberculosis and Thoracic Tumor Institute, Beijing Chest Hospital, Capital Medical University, Beijing 101149, China

    • Hairong Huang

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Contributions

B.J. conceived and oversaw the design and implementation of the project. H.W.S., J.H.Z., C.E., X.W. and H.L. designed and performed the research and analysed the data. R.J.C. and Y.X.C. made and provided reagents. M.K., T.F.Z. and D.M. analysed whole-genome sequencing data. H.H., B.D.K. and B.J. analysed data. H.W.S., J.H.Z. and B.J. wrote the paper with input from the other authors.

Competing interests

The editors note that one of the individuals acknowledged for critical reading of the manuscript, M.C., as well as being a former colleague of the corresponding author, is an editor on the staff of Nature Microbiology, but was not in any way involved in the journal review process.

Corresponding author

Correspondence to Babak Javid.

Supplementary information

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    Supplementary information

    Supplementary Figures 1–11, Supplementary Tables 1–5, Supplementary References.

Excel files

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    Supplementary Tables 6–8

    List of primers, strains and plasmids used in this study.