Type I toxin-antitoxin systems in Bacillus subtilis.

Type I toxin-antitoxin (TA) systems are widespread in bacteria and consist of a toxin-encoding mRNA and a partially overlapping antisense RNA that blocks expression of the toxin, either at the level of translation or by mRNA degradation. Four type I toxin families have so far been proposed in B. subtilis based on sequence similarity: TxpA/BsrG, BsrH/BsrE, YonT and YhzE and two (TxpA and BsrG) have been studied in some detail. Here we review what is known about these confirmed and putative toxin-antitoxin families in B. subtilis, their regulatory mechanisms, their potential roles and how they may link to the physiology of the cell.