Distribution and function of toxin-antitoxin systems in pathogenic

Toxin-antitoxin (TA) system is a genetic module that includes two genes encoding a toxin and its cognate antitoxin respectively. Toxins arrest bacterial growth by inhibiting multiple cellular processes including replication, transcription, and translation, and antitoxins neutralize the toxicity of cognate toxins. Recent genomic and bioinformatics studies have discovered many toxin-antitoxin systems, some of which are involved in bacterial virulence. As Escherichia coli has been recognized its contribution to studying the ecosystem and public health, its pathovar strains have also received attention in the molecular research. The purpose of this review is to summarize the distribution of TA system in pathogenic and non-pathogenic strain of E. coli. Uropathogenic E. coli strain CFT073, adherent-invasive E. coli strain NRG857c, and non-pathogenic E. coli strain K-12 substr. MG1655 were selected for the comparison of TA system's distribution and function. Through analysis, we found that only the type II TA system of the three E. coli strains showed a significant difference in terms of distribution. Thus, 17 type II system of CFT073, 14 type II TA system of NRG857c, and 14 type II system of K-12 substr. MG1655 were discussed further in this review.