AUTHOR=Zheng Cao , Ma Yang , Wang Xun , Xie Yuqun , Ali Maria K., He Jin 

TITLE=Functional analysis of the sporulation-specific diadenylate cyclase CdaS in Bacillus thuringiensis

JOURNAL=Frontiers in Microbiology

VOLUME=6

YEAR=2015

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2015.00908

DOI=10.3389/fmicb.2015.00908

ISSN=1664-302X

ABSTRACT=<p>Cyclic di-AMP (c-di-AMP) is a recently discovered bacterial secondary messenger molecule, which is associated with various physiological functions. In the genus <italic>Bacillus</italic>, the intracellular level and turnover of c-di-AMP are mainly regulated by three diadenylate cyclases (DACs), including DisA, CdaA and CdaS, and two c-di-AMP-specific phosphodiesterases (GdpP and PgpH). In this study, we demonstrated that CdaS protein from <italic>B. thuringiensis</italic> is a hexameric DAC protein that can convert ATP or ADP to c-di-AMP <italic>in vitro</italic> and the N-terminal YojJ domain is essential for the DAC activity. Based on the markerless gene knock-out method, we demonstrated that the transcription of <italic>cdaS</italic> was initiated by the sporulation-specific sigma factor σ<sup>H</sup> and the deletion of <italic>cdaS</italic> significantly delayed sporulation and parasporal crystal formation. These findings contrast with similar experiments conducted using <italic>B. subtilis</italic>, wherein transcription of its <italic>cdaS</italic> was initiated by the sigma factor σ<sup>G</sup>. Deletion of all the three DAC genes from a single strain was unsuccessful, suggesting that c-di-AMP is an indispensable molecule in <italic>B. thuringiensis</italic>. Phylogenetic analysis indicated increased diversity of CdaS in the <italic>B. cereus</italic> and <italic>B. subtilis Bacillus</italic> subgroups. In summary, this study identifies important aspects in the regulation of c-di-AMP in the genus <italic>Bacillus</italic>.</p>