Fig 5.

Genetic organization of novel putative pneumococcal TAS found in this study. (A) Three-component Xre-COG2856CA TAS. The gene for the COG2856C toxin is located upstream of the COG2856A toxin gene, with both toxins possibly sharing a common Xre antitoxin. The xre reading frame overlapped the upstream portion of the COG2856C reading frame. (B to D) For Xre-COG2856B, besides the typical gene organization in which the Xre antitoxin precedes the COG2856B toxin, relBE2 (B), a Zn-peptidase (C), as well as a Zn-peptidase and an unknown gene (D) are found between Xre and COG2856B. (E) For the putative Xre-Bro TAS family, two contrasting gene organizations were evident: the xre antitoxin gene preceded the Bro1 toxin gene, whereas the Bro2 toxin gene preceded the xre antitoxin gene.