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The Involvement of Mycobacterium Type III-A CRISPR-Cas System in Oxidative Stress

Fan Yang1, Lingqing Xu2, Lujie Liang3,4

  • 1Department of Microbiology, School of Basic Medical Science, Xinxiang Medical University, Xinxiang, China.

Frontiers in Microbiology
|December 27, 2021
PubMed

Insights

The Type III-A CRISPR-Cas system (TCC) in Mycobacterium bovis BCG is crucial for maintaining cell envelope integrity and surviving oxidative stress. This system also plays a role in modulating host immunity, suggesting it as a potential therapeutic target.

Area of Science:

  • Microbiology
  • Immunology
  • Molecular Biology

Background:

  • CRISPR-Cas systems are known bacterial defense mechanisms, but the function of type III-A CRISPR-Cas in mycobacteria is largely unknown.
  • Mycobacterium tuberculosis, the cause of tuberculosis, possesses a type III-A CRISPR-Cas system, prompting investigation into its role.

Purpose of the Study:

  • To investigate the functional role of the type III-A CRISPR-Cas system (TCC) in Mycobacterium bovis BCG, particularly under oxidative stress.
  • To determine the impact of TCC on cell envelope integrity, intracellular survival, and host immune modulation.

Main Methods:

  • Generation of a TCC mutant in Mycobacterium bovis BCG.
  • Assessment of mutant sensitivity to hydrogen peroxide and cell envelope integrity.
  • RNA-sequencing to analyze gene expression changes.
  • In vitro and in vivo assays for intracellular survival.
  • Analysis of TCC's effect on regulatory T cell populations.

Main Results:

  • Seven cas genes of the type III-A CRISPR-Cas system were upregulated under oxidative stress.
  • TCC deletion led to increased sensitivity to hydrogen peroxide and compromised cell envelope integrity.
  • TCC influences oxidation-reduction processes and cell wall composition.
  • Disruption of TCC impaired intracellular survival both in vitro and in vivo.
  • TCC was found to regulate regulatory T cell populations, indicating a role in host immune modulation.

Conclusions:

  • The type III-A CRISPR-Cas system (TCC) is essential for cell envelope homeostasis and oxidative stress resistance in mycobacteria.
  • TCC is a significant factor for intracellular survival and host immunoregulation in mycobacteria.
  • TCC represents a potential therapeutic target for tuberculosis treatment.
Keywords:
Mycobacteriumenvelope integrityimmunoregulationoxidative stresstype III-A CRISPR-Cas

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