AUTHOR=Ning Huanhuan , Liang Xuan , Xie Yanling , Bai Lu , Zhang Wei , Wang Lifei , Kang Jian , Lu Yanzhi , Ma Yanling , Bai Guangchun , Bai Yinlan 

TITLE=c-di-AMP Accumulation Regulates Growth, Metabolism, and Immunogenicity of Mycobacterium smegmatis

JOURNAL=Frontiers in Microbiology

VOLUME=Volume 13 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.865045

DOI=10.3389/fmicb.2022.865045

ISSN=1664-302X

ABSTRACT=Cyclic dimeric adenosine monophosphate (c-di-AMP) is a ubiquitous second messenger of bacteria involving in diverse physiological processes as well as host immune responses. MSMEG_2630 is a c-di-AMP phosphodiesterase (cnpB) of M. smegmatis, which is homologous to M. tuberculosis Rv2837c. In this study, cnpB deleted (ΔcnpB), complemented (ΔcnpB::C) and overexpressed (ΔcnpB::O) strains of M. smegmatis were constructed to investigate the role of c-di-AMP in regulating mycobacterial physiology and immunogenicity. This study had provided more precise evidences that elevated c-di-AMP level caused smaller colonies, shorter bacteria length, impaired growth, and inhibition of potassium transporter in M. smegmatis. This is the first report that elevated c-di-AMP level could inhibit biofilm formation, and induce porphyrin accumulation in M. smegmatis by regulating associated-genes expressions, which may have effects on drug-resistance and virulence of mycobacterium. Moreover, the cnpB deletion strain with elevated c-di-AMP level could induce enhanced Th1 immune responses after M. tuberculosis infection, which provided similar protection as wild type M. smegmatis against M. tuberculosis venous infection in mice model. Our findings enhanced the understanding of the physiological role of c-di-AMP in mycobacteria, and M. smegmatis cnpB deletion strain with elevated c-di-AMP level showed the potential for vaccine against tuberculosis.