AUTHOR=Melnicakova Jana , Becarova Zuzana , Makroczyova Jana , Barak Imrich 

TITLE=Analysis of the Bacillus cereus SpoIIS antitoxin-toxin system reveals its three-component nature

JOURNAL=Frontiers in Microbiology

VOLUME=6

YEAR=2015

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2015.00808

DOI=10.3389/fmicb.2015.00808

ISSN=1664-302X

ABSTRACT=<p>Programmed cell death in bacteria is generally associated with two-component toxin-antitoxin systems. The SpoIIS toxin-antitoxin system, consisting of a membrane-bound SpoIISA toxin and a small, cytosolic antitoxin SpoIISB, was originally identified in <italic>Bacillus subtilis</italic>. In this work we describe the <italic>Bacillus cereus</italic> SpoIIS system which is a three-component system, harboring an additional gene <italic>spoIISC</italic>. Its protein product serves as an antitoxin, and similarly as SpoIISB, is able to bind SpoIISA and abolish its toxic effect. Our results indicate that SpoIISC seems to be present not only in <italic>B. cereus</italic> but also in other Bacilli containing a SpoIIS toxin-antitoxin system. In addition, we show that <italic>B. cereus</italic> SpoIISA can form higher oligomers and we discuss the possible role of this multimerization for the protein's toxic function.</p>