High-throughput suppressor selection of a type I toxin-antitoxin system in Helicobacter pylori

As the number of bacterial genomes and transcriptomes increases, so does the number of newly identified toxin–antitoxin (TA) systems. However, their functional characterization remains challenging, often requiring the use of overexpression vectors that can lead to misinterpretations. To fill this gap, we developed a systematic approach called FASTBAC-Seq (Functional AnalysiS of Toxin–Antitoxin Systems in BACteria by Deep Sequencing). Combining life/death phenotypic selection with next-generation sequencing, FASTBAC-Seq allows the rapid identification of loss-of- function (toxicity) mutations in toxin-encoding genes belonging to TA loci with nucleotide resolution. Here, we apply this new tool to study aapA3/IsoA3, a member of a new family of type I TA systems hosted on the chromosome of the major human gastric pathogen Helicobacter pylori. Amplicon DNA sequencing of strains transformed with PCR products of a wild-type or mutated toxin-antitoxin system; in both cases three biological replicate samples were sequenced (6 samples in total)