AUTHOR=Yang Fan , Xu Lingqing , Liang Lujie , Liang Wanfei , Li Jiachen , Lin Daixi , Dai Min , Zhou Dianrong , Li Yaxin , Chen Yong , Zhao Hui , Tian Guo-bao , Feng Siyuan 

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

JOURNAL=Frontiers in Microbiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.774492

DOI=10.3389/fmicb.2021.774492

ISSN=1664-302X

ABSTRACT=<p>Type I and type II CRISPR-Cas systems are employed to evade host immunity by targeting interference of bacteria’s own genes. Although <italic>Mycobacterium tuberculosis</italic> (<italic>M. tuberculosis</italic>), the causative agent of tuberculosis, possesses integrated type III-A CRISPR-Cas system, its role in mycobacteria remains obscure. Here, we observed that seven cas genes (<italic>csm2</italic>∼<italic>5</italic>, <italic>cas10</italic>, <italic>cas6</italic>) were upregulated in <italic>Mycobacterium bovis</italic> BCG under oxidative stress treatment, indicating the role of type III-A CRISPR-Cas system in oxidative stress. To explore the functional role of type III-A CRISPR-Cas system, TCC (<italic><underline>T</underline></italic>ype III-A <italic><underline>C</underline></italic>RISPR<italic>-<underline>C</underline></italic>as system, including <italic>cas6</italic>, <italic>cas10</italic>, and <italic>csm2</italic>-<italic>6</italic>) mutant was generated. Deletion of TCC results in increased sensitivity in response to hydrogen peroxide and reduced cell envelope integrity. Analysis of RNA-seq dataset revealed that TCC impacted on the oxidation-reduction process and the composition of cell wall which is essential for mycobacterial envelop integrity. Moreover, disrupting TCC led to poor intracellular survival <italic>in vivo</italic> and <italic>in vitro</italic>. Finally, we showed for the first time that TCC contributed to the regulation of regulatory T cell population, supporting a role of TCC in modulating host immunity. Our finding reveals the important role of TCC in cell envelop homeostasis. Our work also highlights type III-A CRISPR-Cas system as an important factor for intracellular survival and host immunoregulation in mycobacteria, thus may be a potential target for therapy.</p>